The Science, Microbes & Health Podcast

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  Molecular mechanisms of colorectal cancer development, with Prof. Alberto Martin PhD 20.08.2026 29min

  This episode features Prof. Alberto Martin from University of Toronto (Canada), speaking about the molecular mechanisms by which certain bacteria – namely, pks+ E. coli – influence colorectal cancer development. pks+ E. coli secretes a toxin that causes DNA damage; likely its purpose is to keep other microorganisms in check, but it appears to have the effect of promoting colorectal cancer. A low-fiber diet starves mucolytic bacteria, reducing the mucus layer in the gut and allowing pks+ E. coli to come into contact with the colonic epithelial cells, where they secrete the toxin that causes DNA damage. Gut inflammation also factors in, because these bacteria thrive in an inflammatory environment. Interestingly, in looking at the geographic distribution of this microorganism in people around the world, its presence correlates with colorectal cancer rates. Prof. Martin’s lab has clinical trials planned to explore this connection, and other groups are looking at therapies to reduce this microorganism in the gut. Episode abbreviations and links: Paper on diet and pks+ E. coli interactions in colorectal cancer development: Dietary fibre counters the oncogenic potential of colibactin-producing Escherichia coli in colorectal cancer Paper showing a large proportion of bacterial isolates from IBD patients had DNA-damaging agents: Commensal microbiota from patients with inflammatory bowel disease produce genotoxic metabolites Paper showing correlation of pks+ E. coli in the population and rates of cancer around the world: Geographical variation in the incidence of colorectal cancer and urinary tract cancer is associated with population exposure to colibactin-producing Escherichia coli Paper showing a distinct mutational signature in human cancer genomes, possibly arising from exposure to genotoxic pks+ E. coli: Mutational signature in colorectal cancer caused by genotoxic pks+ E. coli About Prof. Alberto Martin PhD: Dr. Martin is a Professor and Sanofi Pasteur Chair in Human Immunology in the Department of Immunology at the University of Toronto. He completed his B.Sc. degree at McGill University, and his PhD degree in the Department of Immunology at the University of Toronto. He then pursued post-doctoral training at Albert Einstein College of Medicine in New York, U.S.A., with Dr. Matthew Scharff, focusing on characterizing the molecular mechanisms of antibody responses, specifically somatic hypermutation and class switch recombination, which are two processes that are central to the efficient neutralization of pathogens and toxins. In 2003, he was recruited as a faculty member to the Department of Immunology at the University of Toronto. Dr. Martin’s research program is devoted to understanding the role of genes, their interaction with the environment, and their impact on immunity and pathological conditions, including cancer. His main interest is on antibody production, on how high-affinity antibodies are generated, and how antibodies of different classes are produced. Both of these processes are necessary for an efficient antibody response. Dr. Martin is also investigating the role of the gut microbiota in the etiology of colon cancer and has characterizing the role of diet in modulating the cancer causing effects of specific pathobionts. His lab is also investigating the role of a new gene and how it promotes inflammatory bowel disease (IBD). This work highlights the metabolic effects of the skeletal muscle in supporting a metabolically taxing inflammatory process such as IBD.
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  Gut microbiome signatures of colorectal cancer, with Dr. Georg Zeller PhD 06.08.2026 29min

  This episode features Dr. Georg Zeller PhD from Leiden University Medical Center (the Netherlands), speaking about gut microbiome signatures of colorectal cancer across global populations. An early study Dr. Zeller completed in Peer Bork’s lab suggested that the gut microbiomes of people with colorectal cancer are distinct from controls. This signature, as well as work on the tumor microbiome, all pointed toward Fusobacterium as particularly important. Subsequent studies exploring this idea show wide variation in geography and methods. Accounting for these factors, meta-analyses have confirmed several gut microbiome characteristics that are enriched in colorectal cancer across the global population. Dr. Zeller was interested to see that bile acid metabolism is consistently enriched in the cancer metagenome. The taxonomic profile, however, appears better than the functional profile in distinguishing colorectal cancer from control samples. He emphasizes the importance of linking his insights from bioinformatic efforts to the mechanistic work being done. Initially he was hopeful that a gut microbiome diagnostic could be developed, but currently the highest achievable AUC for the classification models is around 0.85 or 0.9, which may not be adequate for enhancing current clinical tools. The possibility remains for a gut microbiome test to complement existing diagnostics. The most promising area may be targeted gut microbiome modulation for prevention of colorectal cancer, perhaps through diet. His group is also exploring the gut microbiome for early diagnosis of pancreatic cancer, possibly by combining fecal markers with other diagnostic tools. Episode links: Early study in French participants suggesting a gut microbiome signature in colorectal cancer: Potential of fecal microbiota for early-stage detection of colorectal cancer Recent meta-analysis from Zeller’s group; Meta-analysis reveals microbiome signatures for colorectal cancer that are universal across age groups and sequencing methods Tools for a combination of 16S rRNA & shotgun sequencing data and meta-analysis approaches: Microbiome meta-analysis and cross-disease comparison enabled by the SIAMCAT machine learning toolbox Paper on the gut microbiota in pancreatic cancer: A faecal microbiota signature with high specificity for pancreatic cancer About Dr. Georg Zeller PhD: Georg Zeller studied Bioinformatics (major in Computer Science) at the Universities of Tübingen (DE) and Uppsala (SE). In 2010 he obtained a PhD from the University of Tübingen (DE) for work performed at the Max Planck Institutes there. Afterwards he joined Peer Bork’s group at EMBL Heidelberg (DE) as a postdoctoral researcher. From 2015 to 2024 he was an independent Team Leader establishing his microbiome research group at EMBL. In 2023 he was appointed as Associated Professor (promoted to full professor in 2025) in the newly formed Leiden University Center for Infectious Diseases (LUCID) at the Leiden University Medical Center (LUMC, NL) to head the Microbiome Systems Biology group. His research is aimed at gaining a better understanding of how the microbiome contributes to human health, disease progression and treatment success, and how it is shaped by host factors such as nutrition and pharmaceutical drugs. To address these questions, his group develops computational, statistical and experimental methods for clinical microbiome studies. His long-term goal is to harness fundamental knowledge on the human microbiome and its interactions with the host for the rational design of microbiome-targeted interventions for prevention and (co-)treatment of disease.
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  Biofilms and specific bacteria in colorectal cancer development, with Prof. Cynthia L. Sears, MD 24.07.2026 29min

  This episode features Prof. Cynthia L. Sears, MD from the Johns Hopkins University School of Medicine and the Bloomberg School of Public Health (USA), speaking about both biofilms and specific gut microorganisms that may contribute to colorectal cancer development. Initially, Prof. Sears became interested in enterotoxigenic Bacteroides fragilis in connection with colon cancer. Further investigation found complex biofilms with multiple bacteria fixed to the surface of the tumor. The biofilms were shown to be oncogenic, and they reassembled very quickly after antibiotic treatment. Interestingly, the biofilms were found to have C. difficile. A subset of the biofilms have a dominant amount of Fusobacterium, and the latest work shows that these bacteria are associated with advancing cancer, stage 2 or beyond. These bacteria and/or biofilms don’t necessarily trigger the onset of mutations that lead to colon cancer, but they accelerate tumor growth. Over time, the gut microbiota may be perturbed in various ways (including by antibiotics), allowing the organisms to create a niche for themselves that ultimately harms the colonic epithelial cells. Prof. Sears is optimistic about prevention strategies for colorectal cancer, such as a tool that helps predict risk in younger populations. Targeted prebiotics, too, show promise for encouraging the growth of beneficial bacteria that prevent the oncogenic species from finding a niche. Episode abbreviations and links: 2014 review by Sears and Garrett on the role of microbes in colon cancer: Microbes, Microbiota, and Colon Cancer One of the landmark 2012 papers linking Fusobacterium nucleatum to colorectal cancer: Fusobacterium nucleatum infection is prevalent in human colorectal carcinoma Examination of biofilms on colon cancer polyps: Epidemiology of bacterial biofilms on polyps and normal tissues in a screening colonoscopy cohort Association of Fusobacterium with advancing (stage 2) colorectal cancer: Tumor-Associated Fusobacterium nucleatum and Aggressive Architectural Features in Stage II Colorectal Cancer Paper showing genotoxic microbes increasing colon tumor burden: Combining genotoxic gut bacterial strains increases tumor burden and accelerates onset in a germ-free mouse model of colon carcinogenesis About Prof. Cynthia L. Sears, MD: Cynthia L. Sears, M.D. is Professor of Medicine, Oncology and Molecular Microbiology and Immunology at the Johns Hopkins University School of Medicine and the Bloomberg School of Public Health. Through her work as an infectious diseases specialist, she studies how bacteria and the microbiome impact gut diseases, particularly human colon cancer. She has long been an active member of the Infectious Diseases Society of America (IDSA), serving as President of IDSA in 2019, is an AAAS Fellow and is currently Editor-in-Chief of The Journal of Infectious Diseases, the flagship journal of the IDSA.
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  The early life gut microbiota in the developmental origins of health & disease, with Dr. Anne Salonen PhD 06.07.2026 29min

  This episode features Dr. Anne Salonen PhD from University of Helsinki (Finland) speaking about her studies on the gut microbiota in early life and how it relates to health and disease. She noted that while mode of delivery (C-section or vaginal birth) is the largest factor affecting microbiota composition for the first weeks and months of life, the immunological and functional microbiota consequences of this are still unknown. However, there appear to be ‘windows of opportunity’ in which microorganisms can influence the development of the immune system, which have lasting consequences for health. Dr. Salonen describes her Finnish HELMi birth cohort, a longitudinal, prospective general population birth cohort, set up to identify factors that modify the gut microbiota and how they relate to child health and wellbeing. Children from 1055 families were sampled frequently in the first 2 years of life and followed as they grew older. The findings confirmed that early-life microbiota composition was a risk factor (among others) for certain diseases as the children developed. Prof. Salonen also described her study on inoculating the infant gut with maternal gut microbiota via milk feeding after C-section birth. They found, in an initial small study, that the gut microbiota of the infants became similar to vaginally born infants. She sees this type of inoculation as a research tool, and says the field will progress toward standardized, reproducible interventions in this area. Episode abbreviations and links: Nature Communications paper showing gut microbiota wellbeing index: Gut microbiota wellbeing index predicts overall health in a cohort of 1000 infants Paper on HELMi birth cohort showing factors affecting gut microbiota in early life: Sources of gut microbiota variation in a large longitudinal Finnish infant cohort Study of maternal fecal microbiota transplantation in infants born by C-section: Maternal Fecal Microbiota Transplantation in Cesarean-Born Infants Rapidly Restores Normal Gut Microbial Development: A Proof-of-Concept Study. Microbes inside (Salonen lab website) About Dr. Anne Salonen: Dr. Anne Salonen is a principal investigator and director of the Human Microbiome Research Program at the Medical Faculty, University of Helsinki. Her research is focused on the intestinal microbiota in health and disease, especially in early life and in relation to diet. Dr. Salonen is a PI of the Finnish Health and Early Life Microbiota (HELMI) birth cohort and involved in maternal fecal microbiota transplantation studies in C-section infants. She is the coordinator of the European Innovation Council Pathfinder project on gut microbiota in precision nutrition (fibrematch.eu). Dr. Salonen’s research also entails female reproductive tract microbiota in relation to reproductive outcomes and Human Papilloma Virus (HPV) infection. Research methodology in Salonen laboratory ranges from NGS and other omics technologies to culture-based microbiology of anaerobes, including application and development of bioinformatic tools for microbiome research. More on our research at https://www.helsinki.fi/en/researchgroups/microbes-inside.
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  Factors affecting infant gut microbiota development, with Prof. Christopher Stewart PhD 17.06.2026 29min

  This episode features Prof. Christopher Stewart PhD from Newcastle University (UK), speaking about the factors affecting gut microbiota development in both non-preterm and preterm infants. Prof. Stewart started in the field of environmental microbial ecology and then came to work in human microbiome research. He was involved in the landmark TEDDY study, which aimed to find gut microbial markers of type 1 diabetes (T1D). Although no microbial triggers of T1D were identified, the study found a number of factors that impact gut microbiome development: for example, sex, geographical location, and living with furry animals. Still, most of the variation seen in the infant gut microbiota remains unaccounted for. He noted that infants are exposed to both vaginal and gastrointestinal microorganisms during vaginal birth. In C-section-born infants, seeding of the maternal vaginal and gut microbiota may be promising, but current methods are imprecise and safety has not been established. Furthermore, diet takes over as a primary driver of gut microbiota a few weeks after birth. Prof. Stewart talked about human milk oligosaccharides (HMOs), well known to be utilized by bifidobacteria in the infant gut. His lab recently published the surprising finding that Clostridium species can also utilize HMOs – and while at first this was thought to be detrimental for the infant, further investigation showed that the HMO-utilizing Clostridium may lack the genes for producing specific toxins and end up being protective for the infant gut. Together, the microbial community in the gut may use the full suite of HMO substrates reaching the infant gut. Preterm infants are a population that needs more attention. Antibiotics affect their gut microbiomes – often in a negative way, but for the overall benefit of the baby. His lab is currently funded to study how probiotics affect the preterm infant gut microbiota, and to find strategies for more personalized approaches to administering probiotics in this population. Episode abbreviations and links: TEDDY study, revealing factors affecting gut microbiota development between 3 and 46 months of age: Temporal development of the gut microbiome in early childhood from the TEDDY study Study on how Clostridium species utilize HMOs: Clostridia from preterm infants metabolize human milk oligosaccharides to suppress pathobionts and modulate intestinal function in organoids Study on how NEC risk is linked with HMOs: Human milk oligosaccharide DSLNT and gut microbiome in preterm infants predicts necrotising enterocolitis  Publication on how probiotics impact the gut microbiota in preterm infants: Strain-specific impacts of probiotics are a significant driver of gut microbiome development in very preterm infants Some similar results have come from the CHILD Cohort Study, described here Find Prof. Stewart on LinkedIn, and learn more about his research on this website About Prof. Christopher Stewart: Professor Christopher Stewart is an internationally recognised leader in human microbiome research. He earned his PhD in Microbial Ecology from Northumbria University (UK), followed by postdoctoral training at Baylor College of Medicine (Houston, Texas), before establishing his research group at Newcastle University in 2018. His pioneering work focuses on microbial-host interactions in the gut, particularly in infants born extremely premature (<32 weeks gestation). His lab integrates multi-omic analyses of clinical samples with experimental microbiology and organoid co-culture systems to uncover mechanisms of microbial influence on early-life development. More recently, he has expanded his research to support a UK-wide initiative investigating microbiome-based predictors of therapeutic response in adult inflammatory bowel disease. Professor Stewart has published over 140 peer-reviewed articles in leading journals, contributing to the discovery of novel biomarkers and targeted microbiome-based interventions. He has received numerous prestigious awards, including the Blavatnik Award for Life Sciences Laureate, the Lister Institute Research Prize, the Microbiology Society Fleming Prize, the NOSTER & Science Microbiome Finalist Prize, the Applied Microbiology International WH Pierce Prize, and the Neonatal Society Rising Star Award.  His research has broad implications for understanding diet–microbe–host interactions and improving health across the life course, miology, maternal and child health, and microbiome science, with a particular emphasis on the effects of vaginal microbiota transfer (VMT) on the microbiota composition and health outcomes of cesarean-delivered infants.
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  A mechanism linking the newborn skin microbiota to neurodevelopment, with Prof. Rihua Xie and Dr. Yuhang Zhang 25.05.2026 29min

  This episode features Prof. Rihua Xie from Guangdong Medical University (China) and Dr. Yuhang Zhang from Peking University First Hospital (China), speaking about vaginal microbiota transfer (VMT) and how it may affect neurodevelopment in newborn infants born by Cesarean section. Compared with vaginally delivered infants, C-section delivered infants have altered microbial exposures. VMT has been proposed as a way to ‘restore’ the microbiota of these infants to more closely resemble that of vaginally-born infants. A recent study by Prof. Xie and Dr. Zhang showed that the order and timing of early microbial colonization of the infant is important. They found that VMT could establish a vaginal-like skin microbiota in infants born by C-section, with two particular bacterial species that were higher after VMT. These two species led to the production of metabolites that combined on the newborn’s skin to synthesize an important lipid, which was positively correlated with neurodevelopment scores at three and six months. Subsequent mouse model work showed how this lipid could reach the brain. In the future, safety and standardization of VMT will be important priorities in this research area. Prof. Xie and Dr. Zhang emphasized that their work needs to be replicated in larger cohorts, with the eventual goal of engineering bacteria to create a probiotic intervention that delivers neurodevelopmental benefits to C-section born infants. Episode abbreviations and links: The research by Prof. Xie and Dr. Zhang demonstrating how a VMT intervention alters the skin microbiota of newborns, with a mechanistic link to neurodevelopment: Vaginal microbiota transfer ameliorates cesarean-associated neurodevelopmental deficits in mice via N-bc2S1P synthesis on neonatal skin About Prof. Rihua Xie: Dr. Ri-hua Xie (RN, PhD, FAAN) is Professor, Principal Investigator, and Chief Nurse at the School of Nursing, Southern Medical University, and the Affiliated Foshan Women and Children Hospital, Guangdong Medical University, China. Dr. Xie is widely recognized for her expertise in maternal and infant health as a clinician, researcher, and supervisor. She has published more than 90 peer-reviewed papers and 11 nursing textbooks and has received 12 competitive research grants from institutions in China and Canada. In addition to her academic work, Dr. Xie is actively engaged in community and public health service, including breastfeeding promotion and frontline support during the COVID-19 pandemic. Her research focuses on perinatal epidemiology, maternal and child health, and microbiome science, with a particular emphasis on the effects of vaginal microbiota transfer (VMT) on the microbiota composition and health outcomes of cesarean-delivered infants. About Dr. Yuhang Zhang: Yuhang Zhang, PhD in Pharmacology, is an Associate Professor and Principal Investigator at Peking University First Hospital. He received his MD-PhD from Capital Medical University and was a visiting scholar at McGill University, Canada. Dr. Zhang’s research focuses on gut microbiome, probiotics, and microbial metabolism in metabolic diseases, who has published over 20 peer‑reviewed papers as first or corresponding author in journals including Gastroenterology, Journal of Hepatology, and Nature Communications, cited >1,000 times. He has led 9 grants, including the National Natural Science Foundation of China, who was selected for the Beijing Association for Science and Technology Young Talent Program (2022) and the China Association for Science and Technology Young Talent Program (2025). The research of Dr. Zhang focuses on the integrated systems pharmacology, multiomics and microbiome‑host interactions to develop precision medicine.
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  Gut microbiota development in preterm and non-preterm infants, with Dr. Marie-Claire Arrieta PhD 07.05.2026 29min

  This episode features Dr. Marie-Claire Arrieta PhD from the University of Calgary (Canada), speaking about development of the early life gut microbiome, both in preterm and non-preterm infants. Across the field, it has been established that the early days and months of an infant’s life are very determinant of immune system development as well as chronic disease later in life. In this period, environmental cues are important, with some of these cues coming from the gut microbiome – both bacteria and fungi. Preterm infants show a very different gut microbiome than non-preterm infants. Ample evidence shows probiotics given to preterm infants can bring clinical benefits such as a reduced risk of necrotizing enterocolitis, but this is separate from investigations into the infants’ gut microbiomes. Dr. Arrieta’s work has shown that probiotics can guide the gut ecosystem of preterm infants toward approximating the non-preterm gut microbiome. One gap in the research is to know more about the effects of specific strains; their work found that although bifidobacteria were more effective at colonizing in the gut, lactobacilli drove some aspects of microbiota maturation. Dr. Arrieta speculates that the case for probiotic use for preterm infants will become stronger as trials increasingly focus on health outcomes not just during the neonatal intensive care unit stay, but also later in life. The CHILD Cohort Study has found that overall in healthy infants, different patterns of gut microbiome and immune development can lead to the appearance of diseases later in life. The latest insight is that disease is linked not to specific microbes or metabolites, but to the pace of gut microbiome development. Misalignment of gut microbiome development (too early or too late) with stages of immune development is associated with later emergence of allergic disease. Several factors such as C-section birth and antibiotics may contribute to this misalignment, but breastfeeding seems to mitigate it. Dr. Arrieta has an ongoing longitudinal study on the early life microbiota and disease associations in preterm and non-preterm infants that is likely to reveal more details. Episode abbreviations and links: Study from Arrieta lab showing effects of a probiotic on the gut microbiome of preterm infants: Supplementation with a probiotic mixture accelerates gut microbiome maturation and reduces intestinal inflammation in extremely preterm infants Study combining preterm infant data from several countries, showing links between gut microbiota, immune system development, and late-onset sepsis: Gut microbiota immaturity with DL-endopeptidase deficiency links antibiotic use to preterm late-onset sepsis Arrieta lab website: https://www.arrietalab.com/ Let Them Eat Dirt website with resources for the general public: https://letthemeatdirt.com/ About Dr. Marie-Claire Arrieta PhD: Dr. Marie-Claire Arrieta is a Professor and Research Excellence Chair at the Cumming School of Medicine, University of Calgary. Her research examines interactions between the early-life gut microbiome and infant development. Her program integrates clinical and experimental approaches to uncover mechanisms of host–microbiome communication. Her work, published in leading journals, has accumulated over 12,000 citations. She has presented her research internationally through more than 120 invited talks to scientific, medical and public audiences. A dedicated mentor, she has supervised over 45 undergraduate, medical, PhD, and postdoctoral trainees. Her contributions have been recognized with the CIHR-SickKids New Investigator Award, the Killam Emerging Research Leader Award, and election to the College of New Scholars of the Royal Society of Canada. Dr. Arrieta is co-author of the best-selling public book, Let Them Eat Dirt, and is involved in several science communication initiatives.
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  Toward skin microbiome interventions for anti-aging and wound healing, with Prof. Hariom Yadav PhD 22.04.2026 25min

  This episode features Prof. Hariom Yadav PhD, from the University of South Florida (USA), speaking about the skin microbiome and potential interventions for anti-aging and wound healing. Prof. Yadav noted that humans have a stable (core) microbiome on the surface of skin cells, plus a transient microbiome that depends on recent exposures. The skin microbiome constantly changes through the lifespan, and in aging, many skin conditions are correlated with the microbiome. Animal studies show a causal component of the microbiome in some of these conditions. However, because of the large skin microbiome differences from person to person and in narrow age groups, technologies or products may have to be designed in a personalized way. Prof. Yadav’s lab conducted experiments with lactobacilli and found strain-dependent effects of probiotics on anti-aging, and for some strains these effects persisted when the inactivated bacteria (postbiotics) were used. The postbiotics have commercial advantages over probiotics in this area of health. Prof. Yadav described an application in wound healing, building on the idea that microbial stimulation promotes natural skin cell growth and more fibroblasts. A standard treatment for wound healing is effective but may lead to scarring; the postbiotic treatment leaves less scarring. The efficacy of the postbiotic occurs because inactivated bacteria still give growth-promoting signals to the skin cells. Applying metabolites directly may not be as effective because bacterial cells or extracts work on host cells, which changes the skin environment and further supports positive skin microbiome changes. Episode abbreviations and links: Jeffrey Gordon’s landmark paper in 2006: An obesity-associated gut microbiome with increased capacity for energy harvest Review on the skin microbiome and aging by Prof. Yadav and colleagues: Microbiome-Aging-Wrinkles Axis of Skin: Molecular Insights and Microbial Interventions Review on postbiotic skin interventions by Prof. Yadav and colleagues: Microbiome and Postbiotics in Skin Health About Prof. Hariom Yadav PhD: Dr. Hariom Yadav is a Professor at the University of South Florida and Director of the USF Center for Microbiome Research, and co-founder of Postbiotics Inc (www.postbioticsinc.com) and MusB Research (www.musbhealth.com). With over 25 years of experience, he specializes in microbiome science, biotics, nutrition, longevity, and natural products for optimal wellness. He has authored 200+ peer-reviewed publications, holds/filed 7 patents, mentored over 80 scientists, and has successfully translated multiple innovations into commercially viable products. Dr. Yadav works closely with industry partners to accelerate product development—from discovery and mechanistic validation to clinical trials and regulatory readiness. He leads global collaborative efforts, including the MELLOW (Multi-continental Evidence of Longevity and Lifestyle for Optimal Wellness) consortium, a unique platform for scalable, multi-region clinical validation. His integrated approach enables companies to build scientifically robust, market-ready products with strong differentiation and credibility. He is committed to moving science from bench to market, delivering measurable health impact and commercial success.
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  Inflammatory microbes on the skin, with Dr. Nathan Archer PhD 08.04.2026 29min

  This episode features Dr. Nathan Archer PhD from Johns Hopkins Medicine (USA), speaking about the skin microbiome and particular microorganisms that cause inflammation. The skin is a dynamic organ with the main functions of keeping moisture in and keeping the environment out. Overall, the skin environment is not very welcoming to microorganisms but some have adapted to thrive in the low pH environment. His research has found that certain bacteria that are normally considered commensals can become pathogenic when they start producing specific proteases that instigate inflammation on the skin. Acute inflammation that removes a bacterial exposure from the skin is beneficial, but chronic inflammation can be a major problem. Staphylococcus aureus is a bacterium that predominates in many inflammatory skin diseases and benefits from an inflammatory environment and disruption in the skin barrier; in turn, S. aureus is proinflammatory and uses proteases to drive skin inflammation. His lab is interested in understanding the connection between skin microorganisms and the ‘atopic march’ (progression of allergic diseases, including atopic dermatitis, through infancy and childhood). They found that S. aureus on the skin can exacerbate allergic reactions in the lungs, driving hard-to-treat neutrophilic asthma. His group is contributing to several strategies for preventing / treating skin and allergic diseases, including a vaccine for S. aureus; so far, vaccines against this bacterium have not succeeded because S. aureus has so many tools for avoiding human immune responses. However, a multivalent vaccine targeting multiple toxins that affect the immune system is currently being developed and is in Phase 1 clinical trials. Episode abbreviations and links: Paper on the contribution of microorganisms to normal skin function: Commensal Staphylococcus epidermidis contributes to skin barrier homeostasis by generating protective ceramides Research on the mechanisms of how S. aureus triggers skin inflammation: Staphylococcus aureus proteases trigger eosinophil-mediated skin inflammation Study on the mechanisms by which S. aureus causes epithelial barrier damage: Quorum sensing between bacterial species on the skin protects against epidermal injury in atopic dermatitis Review article on how S. aureus contributes to skin inflammation: Staphylococcus aureus Proteases: Orchestrators of Skin Inflammation Connection of skin microbes to allergic diseases: Epicutaneous Staphylococcus aureus initiates cross-tissue IL-36R signaling for neutrophilic lung inflammation in a model of the atopic march Treatment approach for atopic dermatitis: Development of a human skin commensal microbe for bacteriotherapy of atopic dermatitis and use in a phase 1 randomized clinical trial About Dr. Nathan Archer PhD: Dr. Nathan Archer is an Associate Professor at the Johns Hopkins School of Medicine Department of Dermatology. Dr. Archer’s research involves uncovering how skin microbes, especially the major human pathogen Staphylococcus aureus, exacerbate inflammatory skin diseases such atopic dermatitis as well as how host immunity protects against bacterial skin infections. His work involves the incorporation of immunological and “omic” approaches with preclinical models and clinical samples to reveal mechanistic insights with translational relevance to human disease. His long-term research goals are to develop novel host-directed therapies for the treatment of inflammatory skin disorders and skin infections. Dr. Archer has received funding from the NIH as well as from foundation and industry sources, including the Dermatology Foundation, LEO Foundation, and Pfizer. He has been an invited speaker at numerous international and national conferences with a focus on dermatology, immunology, and microbiology.
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  The skin microbiome’s role in atopic dermatitis, with Dr. Maria Teresa García-Romero, MD MPH 24.03.2026 29min

  This episode features Dr. Maria Teresa García-Romero, MD MPH from the National Institute of Pediatrics in Mexico City, talking about the skin microbiome and how it relates to atopic dermatitis. The skin microbiome varies widely at different sites on the body, but in general, increased diversity is associated with healthy skin. In atopic dermatitis, Staphylococcus aureus becomes abundant and skin microbiome diversity decreases, correlating with inflammatory responses. Treatments have the effect of reducing Staphylococcus aureus. These bacteria are now established to have a role in the pathophysiology of the disease. The caution with antibiotic treatment is that a systematic review and meta-analysis from Dr. García-Romero’s group found Staphylococcus aureus isolates from people with atopic dermatitis had suboptimal susceptibility to commonly used antimicrobials, especially in lower middle-income and upper middle-income countries. Mechanistically, Staphylococcus aureus decrease natural antimicrobial molecules in the skin, stimulate the innate immune response, and likely reduce beneficial bacteria. New treatments are urgently needed because atopic dermatitis is very prevalent (affecting 20-30% of the population), with far-reaching effects in children’s and families’ lives. Two ingested probiotics are commercially available for atopic dermatitis, backed by clinical data, whereas topical probiotic treatments require further research. Episode abbreviations and links: Paper showing how treatments for atopic dermatitis help the skin microbiome more closely resemble healthy controls: The Skin Microbiome of Patients With Atopic Dermatitis Normalizes Gradually During Treatment Systematic Review and Meta-Analysis looking at susceptibility of atopic-dermatis associated Staphylococcus aureus to antibiotics in different regions of the world: Global Antimicrobial Susceptibility Patterns of Staphylococcus aureus in Atopic Dermatitis About Dr. Maria Teresa García-Romero: Dr. Maria Teresa García-Romero is a medical doctor graduated from Tec de Monterrey School of Medicine, magna cum laude. She has a Specialty in Dermatology and Diploma in Medical Mycology from UNAM, Mexico City. Dr. García-Romero completed a Fellowship in Pediatric Dermatology at the University of Toronto, and a Master’s degree in Public Health and Quantitative methods of research at Harvard University Chan School of Public Health.  She has received meritorious awards including the Mexican Foundation for Health (FUNSALUD), Harvard University Presidential Award, Society for Pediatric Dermatology Fellow Award, among others; and funding for research projects by prestigious international organizations such as MIT (Massachusetts Institute for Technology) seed funds and EB Research Partnership.  She is currently an attending physician in the Dermatology Department of the National Institute of Pediatrics in Mexico City and a member of the National System of Researchers level II. She has more than 150 articles published in national and international magazines, supervised multiple postgraduate theses and has presented in multiple forums worldwide. Dr. García-Romero is a member of the Editorial Committee of JAMA Dermatology, Pediatric Dermatology and other high impact journals. Her research interests include the skin microbiome, atopic dermatitis, vascular anomalies and autoimmune disease.
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  An introduction to skin microbiome research, with Dr. Aayushi Uberoi PhD 12.03.2026 29min

  This episode features Dr. Aayushi Uberoi PhD from Washington University in St. Louis (USA), speaking about the skin microbiome and various techniques for studying it. The skin is a reactive interface that protects the body, with the skin on various parts of the body looking very different because of stratifications in the epithelial layers and the local nutritional landscape. The skin microbiome in general is nutrient sparse and varies at different body sites. Research has shown that epithelial development, stratification, and differentiation are altered in the absence of the microbiota, showing the active role of the skin microbiota in regulating skin function. Microbes that inhabit the skin are shown to elicit unique immune responses with systemic effects. Communication between skin microbes and human body cells may be happening via metabolites. When conducting skin microbiome experiments, controls are important; the low biomass samples are susceptible to contamination. In the future, knowing more about the nutritional needs of the skin microbes could help guide the development of prebiotics for skin. Episode abbreviations and links: Paper showing a humanized mouse model for studying the skin microbiome: Commensal-derived tryptophan metabolites fortify the skin barrier: insights from a 50-species gnotobiotic model of human skin microbiome Paper on the skin microbiome’s contributions to wound healing: The wound microbiota: microbial mechanisms of impaired wound healing and infection Paper investigating mechanisms of how skin microbes influence skin function: Commensal Microbiota Regulates Skin Barrier Function And Repair Via Signaling Through The Aryl Hydrocarbon Receptor Review by Belkaid and Segre: Dialogue between skin microbiota and immunity About Dr. Aayushi Uberoi PhD: Aayushi Uberoi is an Assistant professor of Pathology & Immunology and Medicine (Dermatology) in Washington University School of Medicine in Saint Louis. Her lab studies the host-microbe-environment interactions in regulating skin barrier. She  has studied interactions between microbes and skin since her Ph.D. research on cutaneous papillomaviruses in Dr. Paul Lambert’s lab at the University of Wisconsin-Madison. While traditional studies of infectious skin diseases have typically focused on singular pathogens within the host, skin is colonized by a diverse array of microbes, which likely exert significant influence on epithelial characteristics. Motivated by this question, Aayushi’s postdoctoral research at the University of Pennsylvania in Dr. Elizabeth Grice’s lab explored the role of the commensal microbiome in regulating the function of the cutaneous barrier. In the lab, Aayushi wears several hats such as conducting research, developing protocols and assays, writing, and making sure the lab has fun equipment.  Aayushi is a recipient of K99/R00 Pathway to Independence award from National Institute of Arthritis & Musculoskeletal & Skin Diseases (NIAMS/NIH), innovator award from Society of Investigative Dermatology, fellowships from Prevent Cancer Foundation and Dermatology Foundation and a Young Investigator Award from the Wound Healing Society. 
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  ISAPP’s scientific consensus definition of gut health 22.02.2026 29min

  This episode features two guests from the ISAPP board of directors who led the recently published consensus definition of gut health: Prof. Maria Marco PhD from UC Davis (USA), and Prof. Eamonn Quigley MD from Houston Methodist Hospital (USA). In the paper, the group defines gut health as: “a state of normal gastrointestinal function without active gastrointestinal disease and gut-related symptoms that affect quality of life”. Gut health is a commonly used term that previously had no scientific definition. Initially the group of experts (both scientists and physicians) that met to discuss it had a lot of skepticism, but they became more enthusiastic and engaged as the discussion proceeded and were finally able to reach consensus. The group identified 6 distinct domains that are encompassed under gut health: gut microbiome, gut barrier, gastrointestinal physiology (primarily intestinal secretions and motility), gut-brain axis, immune function, and metabolism. The group hopes it will provide clarity over time about which aspect(s) of gut health are being assessed in a given study (as it’s not realistic to look at all aspects in a single study). One difficulty is that some of the tests available to measure these domains are quite limited and/or invasive. Nor do consistent correlations exist between symptoms and objective measures of the 6 domains. Determinants of gut health are also discussed in the paper, with diet being important among these. Episode abbreviations and links: Gut health consensus definition paper: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of gut health Earlier publication on gut health by Bischoff: ‘Gut health’: a new objective in medicine? About Prof. Maria Marco PhD: Dr. Maria Marco PhD, is President of ISAPP’s board of directors and Professor in the Department of Food Science and Technology at the University of California, Davis. She earned her PhD in microbiology at the University of California, Berkeley. Prof. Marco started her lactic acid bacteria and gut health laboratory at UC Davis in 2008 and has built an internationally-recognized, NIH, USDA, and NSF funded research program on probiotics, fermented foods, and dietary modulation of the gut microbiome. She is currently a fellow in the American Academy of Microbiology. About Prof. Eamonn Quigley MD: Dr. Eamonn M M Quigley MD FRCP FACP MACG FRCPI MWGO is David M Underwood Chair of Medicine in Digestive Disorders and Chief of the Division of Gastroenterology and Hepatology at Houston Methodist Hospital. A native of Cork, Ireland, he graduated in medicine from University College Cork. He trained in internal medicine in Glasgow, completed a two-year research fellowship at the Mayo Clinic, and training in gastroenterology in Manchester, UK. He joined the University of Nebraska Medical Center in 1986 where he rose to become Chief of Gastroenterology and Hepatology. Returning to Cork in 1998 he served as Dean of the Medical School and a PI at the Alimentary Pharmabiotic Center. He served as president of the American College of Gastroenterology and the WGO and as editor-in-chief of the American Journal of Gastroenterology.
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  2025 highlights in biotic science 17.12.2025 29min

  This special year-end episode, which covers 2025’s highlights in biotic science, features three of the academic scientists who serve on the ISAPP board of directors: Prof. Maria Marco PhD from University of California, Davis (USA), Prof. Sarah Lebeer PhD from University of Antwerp (Belgium), and Dr. Gabriel Vinderola PhD from National University of Litoral (Argentina). After a brief review of ISAPP’s activities, the host, Prof. Colin Hill PhD from University College Cork (Ireland) asks the three guests about the talks that stood out from the ISAPP annual meeting. The guests cited talks by Prof. Howard Bauchner MD on publishing and the scientific communication ecosystem; Dr. Carolina Tropini PhD on factors affecting the gut microbial environment and engineering gut microbes as biosensors; and Dr. Peijun Tian PhD on a microbial metabolite that can signal to the brain to relieve depression through the gut-brain axis. The guests also described some stand-out papers published this year (linked below). Finally, they discussed how science is informing regulatory issues in different parts of the world, and shared some research from their own labs that they’re particularly excited about. Episode abbreviations and links: Paper from Dr. Peijun Tian PhD showing a microbial metabolite that signals through the gut-brain axis: Bifidobacteria with indole-3-lactic acid-producing capacity exhibit psychobiotic potential via reducing neuroinflammation NiMe diet paper: Cardiometabolic benefits of a non-industrialized-type diet are linked to gut microbiome modulation (also see this podcast episode) Paper on a host colonization factor in L. plantarum: A conserved bacterial genetic basis for commensal-host specificity Research presented at a congress this year on maternal feces given to infants: Eating a tiny bit of mom’s poop could give C-section babies an immune ‘primer’ Paper from Marco lab on microbial metabolites in sauerkraut: The fermented cabbage metabolome and its protection against cytokine-induced intestinal barrier disruption of Caco-2 monolayers
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  Trials on probiotics and prebiotics in infant formula, with Prof. Yvan Vandenplas MD PhD 03.12.2025 29min

  This episode features Prof. Yvan Vandenplas MD PhD from the University Hospital Brussels and Vrije Universiteit Brussel (Belgium), speaking about the science on probiotics and prebiotics in infant formula. Over the past 20 years in this field, awareness of the importance of the gastrointestinal microbiota has grown, and biotics have been employed to try to shape the gut microbiota of infants formula-fed to resemble that of breastfed infants. In particular, human milk oligosaccharides (HMOs) are prebiotics that are shown to change the microbiota composition, although the clinical benefits of these changes are not yet clear. What clinical benefits are achievable for infants who receive formula with added probiotics or prebiotics? Looking closely at the trials, it’s evident that probiotics and prebiotics are associated with a decrease in infections and antibiotic prescriptions, but researchers need to use these as primary endpoints in their trials to increase the strength of the evidence. In a recent European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) recommendations paper, the probiotic recommendations were challenging because for each specific probiotic intervention the group had difficulty finding two clinical trials with a similar design, limiting their ability to make conclusions. Prof. Vandenplas says more trials need to be done independently to strengthen the evidence. Long-term outcomes from probiotic or prebiotic supplementation in infant formula are possible as well, but much larger longitudinal trials are necessary to establish these outcomes. Episode abbreviations and links: ESPGHAN recommendations paper: Recommendations on the health outcomes of infant formula supplemented with biotics by the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition Special Interest Group on Gut Microbiota and Modifications Trial showing positive outcomes of an infant probiotic and prebiotic intervention in a region with high prevalence of infectious disease: A randomized synbiotic trial to prevent sepsis among infants in rural India About Prof. Yvan Vandenplas MD PhD: Yvan Vandenplas did his medical studies at the ”Vrije Universiteit Brussel” (Free University of Brussels) and trained in pediatrics (1981-1986) at the same University. He became Head of the Unit for Pediatric Gastroenterology and Nutrition in 1987 and created the Pediatric Hospital, the KidZ Health Castle, at the University Hospital Brussels (UZ Brussel) of the same university, where he had the Chair of Pediatrics since 1994 up to 2021. He is now Prof. Emeritus and consultant at the same hospital. He is associate editor of Nutrients.
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  Dietary management of chronic constipation, with Dr. Eirini Dimidi PhD RD 25.11.2025 29min

  This episode features Dr. Eirini Dimidi PhD RD from King’s College London (UK), speaking about the recently published British Dietetic Association’s guidelines for dietary management of chronic constipation. Constipation can be a major concern for patients, but evidence around some of the most common dietary recommendations for addressing it has remained unclear. After a thorough review of evidence from randomized, controlled trials, Dr. Dimidi and colleagues found evidence for specific foods / beverages improving certain symptoms of constipation. In addition, some supplements such as psyllium, certain probiotics, and magnesium oxide have evidence for efficacy. A high-fiber diet is a commonly recommended dietary strategy for chronic constipation, but the guideline shows that the evidence to date is insufficient to support this recommendation. (However, a high fiber diet has many other benefits.) Probably the effective foods’ key mechanism of action in relieving symptoms of constipation is the fiber they contain, but future studies need to confirm this. Regarding probiotics, so far the evidence is ambiguous around which strains and which durations of treatment are the most effective so the authors were unable to make a confident conclusion. However, for practical reasons they included the expert opinion that patients should be advised to take a probiotic of their choice for at least 4 weeks in addressing chronic constipation. Episode abbreviations and links: 2025 guidelines: British Dietetic Association Guidelines for the Dietary Management of Chronic Constipation in Adults 2019 review on fermented foods & gastrointestinal outcomes: Fermented Foods: Definitions and Characteristics, Impact on the Gut Microbiota and Effects on Gastrointestinal Health and Disease LinkedIn profile for Dr. Dimidi About Dr. Eirini Dimidi PhD RD: Dr Eirini Dimidi is an Associate Professor in Nutritional Sciences at King’s College London. She is a registered dietitian and nutritionist since 2011, after completing a BSc in Nutrition and Dietetics and a MSc in Clinical and Public Health Nutrition. This was followed by the completion of a PhD from King’s College London where she investigated the effectiveness of probiotics in people with chronic constipation. She is leading research on nutrition-based interventions, including fibre, prebiotics, probiotics, plant foods, and plant-based diets in gut function and dysfunction. She is also investigating the mechanisms through which nutritional interventions may affect immune and mental health via the gut microbiome. Dr Dimidi led the development of the first ever UK national dietary guidelines for the management of chronic constipation, which have been endorsed by the British Dietetic Association. Dr Dimidi was awarded the 2023 Cuthbertson Medal by the Nutrition Society, and the 2022 ISAPP Glenn Gibson Early Career Research Prize for her research on the effect of diet in gut health. She also received the 2021 Rising Star and 2020 Elizabeth Washington awards by the British Dietetic Association.
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  How ecological dynamics affect pathogens in the gut, with Prof. Kevin Foster PhD 06.11.2025 29min

  This episode features Prof. Kevin Foster PhD from University of Oxford (UK), speaking about his lab’s ecological approach to the gut microbiome and efforts to understand and predict dynamics of different species in the microbiome. They also focus on how these ecological dynamics map onto health outcomes, and how they inform interventions. In a 2023 paper, they explored the concept of colonization resistance in the gut, and why certain bacteria or combinations of bacteria are particularly good at preventing pathogens from thriving. Both diversity and composition are important for determining the extent to which a community resists a pathogen. But a microbiome may equally resist a probiotic that’s introduced because the probiotic microorganism doesn’t have access to a unique nutrient. How bacteria interact with each other can help determine resiliency or stability of the microbiome overall. While it’s true that hundreds of species of bacteria exist in the gut, the scale at which the microbes interact locally is much more limited (on the scale of tens of species). Episode abbreviations and links: 2023 paper examining colonization resistance against 2 pathogens: Microbiome diversity protects against pathogens by nutrient blocking.  About Prof. Kevin Foster PhD: Professor Kevin Foster FRS is the Chair of Microbiology at the Dunn School of Pathology, University of Oxford. Prior to this, he was Professor of Evolutionary Biology in the departments of Biology and Biochemistry at Oxford. Before Oxford, he had a lab at Harvard as a Bauer Fellow in the FAS Center for Systems Biology. He did his undergrad at Cambridge in Natural Sciences and his Ph.D. at the University of Sheffield in evolutionary biology. Professor Foster’s research integrates the traditional fields of ecology and evolution with the latest methods in computation, microbiology, molecular genetics, and the study of the mammalian microbiome. The lab focuses on how bacteria compete and succeed in their communities and seeks to use this to manipulate gut communities for better health.
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  Applying the tools of ecology to manage microbiomes in people with cancer, with Dr. Joao Xavier PhD 24.10.2025 29min

  This episode features Dr. Joao Xavier PhD, a systems biologist from Memorial Sloan Kettering Cancer Center, speaking about the application of ecological principles and tools to individuals being treated for cancer. His lab combines multi-omics profiling with ecological models to generate insights on how microbes interact with each other, for application to clinical risk prediction and microbiota-focused interventions. He has studied individuals receiving bone marrow transplantation, who take antibiotics to prepare for treatment; the antibiotics cause significant gut microbiota shifts and the risk of bloodstream infections increases, so his lab is looking at whether the gut microbiota could mitigate this risk. Currently microbiome monitoring is not being used clinically in patients receiving cancer treatments, but a path exists for gaining the evidence needed to make this feasible and useful. Potentially, microbiome monitoring could allow physicians to move from reactive treatment with antibiotics to proactive intervention that prevents serious infections. Or the clinician could simulate potential treatment scenarios and figure out which one is the most beneficial. Probiotics could be administered to shape the microbiome – but rather than adding microorganisms that may simply be missing, these probiotics would be developed by thinking about the microbiome outcome and how to pressure the ecosystem in a certain direction. Episode abbreviations and links: Review in Nature Reviews Clinical Oncology, arguing for the relevance of microbiota management guided by ecological principles in cancer care: making the case for Ecological management of the microbiota in patients with cancer Mouse study investigating what may drive an increase in oral bacteria within the fecal microbiota and how it may link to patient outcomes: Oral bacteria relative abundance in faeces increases due to gut microbiota depletion and is linked with patient outcomes About Dr. Joao Xavier PhD: Joao B. Xavier, PhD, is a faculty member in the Program for Computational and Systems Biology at Memorial Sloan Kettering Cancer Center in New York. His lab combines experiments, computational modeling, and clinical data to study how the human microbiota influences cancer treatment outcomes. Dr. Xavier’s work has uncovered links between gut bacteria, immune recovery, and infection risk in patients undergoing intensive therapies such as allogeneic hematopoietic stem cell transplantation. He recently authored a Nature Reviews Clinical Oncology article (2025) proposing “ecological management” of the microbiota in oncology. This approach applies principles of ecosystem management to preserve beneficial microbes, minimize treatment-related damage, and guide precision interventions. He was awarded the 2026 ASM Microbiome Data Prize by the American Society for Microbiology in recognition of these contributions. His group collaborates broadly across clinical and basic sciences to develop microbiota-informed strategies that could improve responses to chemotherapy, immunotherapy, and infection control.
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  Insights from evolutionary ecology on microbiome assembly and modulation,  with Prof. Jens Walter PhD 08.10.2025 29min

  This episode features Prof. Jens Walter PhD, a microbial ecologist from University College Cork / APC Microbiome Ireland, explaining how he applies ecological and evolutionary frameworks for the purposes of understanding and modulating microbiomes. Although there appears to be a high amount of stochasticity (or randomness) in microbiomes, stochastic and deterministic elements work together to determine outcomes. Priority effects (based on arrival order of a bacterium or other microorganism) are important, with communities likely taking shape through a combination of priority effects and adaptation to the niche. The potential to modulate the microbiome is high in early life, as there are many ecological possibilities. For established microbiomes (for example, in adults), Prof. Walter’s group has found that diet (for example, the “NiMe” diet they developed)  is a possible way to modulate the microbial community, although the effect on the overall ecosystem is small. Nevertheless, dietary modulation may have positive and important effects on host health. Episode abbreviations and links: Paper showing how fiber precisely modulates the gut microbiome: Precision Microbiome Modulation with Discrete Dietary Fiber Structures Directs Short-Chain Fatty Acid Production About Prof. Jens Walter PhD: Jens Walter serves as the Professor of Ecology, Food, and the Microbiome at University College Cork and the APC Microbiome Ireland. His expertise lies at the interface of evolutionary ecology of the gut microbiome and human nutrition. His research focuses on the evolutionary and ecological processes that have shaped host-microbiome symbiosis and the translation of basic microbiome science into therapeutic and nutritional strategies. Dr. Walter and his collaborators have pioneered the application of ecological theory to elucidate ecological and nutritional factors that shape gut microbiomes and have achieved targeted modulations of microbiomes via dietary strategies and live microbes. Prof. Walter has published >140 peer-reviewed publications (google scholar H-index 69, >23,000 citations) and is a ‘highly cited researcher’ according to the Web of Science group.
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  Eco-evolutionary processes and antimicrobial resistance in the urobiome, with Dr. Marjon de Vos PhD 25.09.2025 27min

  This episode features Dr. Marjon de Vos PhD from the University of Groningen (the Netherlands) speaking about microbial ecology and evolution, and in particular how these affect antimicrobial resistance. She studies the urobiome as well as the factors that contribute to urinary tract infections and successful treatment of these infections with antibiotics. Her lab combines molecular biology techniques with phenotypic and growth measurements, as well as computational modeling. She has found evidence of microbial interactions mediating evolutionary potential of microorganisms – for example, in vitro experiments showed that in the presence of Enterococcus, E. coli speeds up its rate of developing antimicrobial resistance. Thus, interactions within the bacterial ecosystem may affect pathogens’ sensitivity to antimicrobials. Prebiotics are a potential intervention: if bacteria that make a pathogen more susceptible to antimicrobials are already present in the urobiome, their numbers could be enhanced. Probiotics are another possibility. From a One Health perspective, such approaches are important to explore because they support antimicrobial stewardship and help maintain control of antimicrobials in the environment overall. Episode abbreviations and links: Preprint describing pathogens’ differing rates and evolutionary trajectories towards antibiotic resistance based on other microbes present: Microbial interactions affect the tempo and mode of antibiotic resistance evolution Paper describing ecological interactions between different bacterial species in urinary tract infections: Interaction networks, ecological stability, and collective antibiotic tolerance in polymicrobial infections Research showing how 5 different bacteria affect the conjugation efficiency of E. coli: Community context influences the conjugation efficiency of Escherichia coli  About Dr. Marjon de Vos PhD: We investigate ecological and evolutionary processes in microbial communities, with a focus on infectious contexts. Our goal is to unravel the genotype–phenotype–fitness relationships within (evolving) communities and to identify the ecological factors that drive microbial evolution. To achieve this, we combine molecular biology techniques with phenotypic and growth measurements, as well as computational modeling. Our research places special emphasis on the urobiome and urinary tract infections in postmenopausal women, as well as on sepsis. By uncovering the fundamental ecological and evolutionary dynamics of microbial communities in infectious diseases, we aim to contribute to the development of strategies that alleviate infections and help curb the emergence and spread of antibiotic resistance.
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  Highlighted Posters from the 2025 ISAPP Annual Meeting 27.08.2025 22min

  In this second special episode about ISAPP’s annual meeting, held in Banff (Canada) in July 2025, Executive Director Marla Cunningham introduces the four highest-scoring posters from the poster session. Four speakers, all members of the ISAPP Students and Fellows association (SFA), join the podcast to describe the work they presented via poster at the meeting: Benjamin Levine (University of Illinois Urbana-Champaign, USA): Individual intestinal motility responses to acute whole-grain prebiotic ingestion mediates post-prandial nutrient metabolism: a single-blind randomized controlled clinical trial Caroline Dricot (University of Antwerp, Belgium): Isala citizen-science study: navigating the vaginal microbiome’s metabolic landscape Ceylon Simon (University College Cork and APC Microbiome Ireland; fellow in the Marie Skłodowska-Curie Actions “Cell Envelope Anti-Bacterials”, or CLEAR, Doctoral Network): Targeted microbiome editing using a novel bacteriophage-derived endolysin with lytic activity against C. difficile  Dr. Qinnan Yang, PhD (University of Michigan, USA): Synergistic interaction of Akkermansia muciniphila and mucin-degrading Bacteroides in Inflammatory bowel diseases Episode abbreviations and links: The ISAPP Annual Meeting Program Guide, with abstracts for each poster presentation Sign up for our monthly newsletter Follow us on LinkedIn, Bluesky, X, Facebook, Instagram, Threads