Imperial College London


Faculty of MedicineDepartment of Metabolism, Digestion and Reproduction

Professor of Digestive Health



+44 (0)20 3312 6197j.marchesi




Queen Elizabeth the Queen Mother Wing (QEQM)St Mary's Campus





Julian Marchesi graduated from Cardiff University with a PhD in biochemistry (1992) and became interested in the role bacteria play in ecosystem function. During his post-doctoral years he developed an interest in the contribution of uncultured microbes to the maintenance and function of ecosystems i.e. molecular microbial ecology. He subsequently secured a Wellcome Trust Fellowship which extended his molecular microbial ecology interest and investigated, with culture independent methods, the diversity and distribution of genes involved in biodegradation of priority pollutants in pristine environments. After a short time investigating the deep biosphere he obtained a Lectureship (2001) in the Department of Microbiology, University College Cork, Ireland where he transferred these “omic” skills into the human gut and started to investigate the human gut ecosystem in health and disease. After 7 years in UCC, he moved back to Cardiff University in 2008 to a senior lectureship, where he investigates the role of the gut microbiome in maintaining host health and initiating diseases not only of the gut, but throughout the host system.  In 2015 he was promoted to Professor at Cardiff and in 2016 to Professor at Imperial College London.

His work uses a variety of “omic” approaches such as metagenomics, metatranscriptomics, metabonomics and molecular ecology.  Over his 22 year career he has authored over 190 journal articles and peer-reviewed publications and is a senior editor for ISME Journal. He is the current chair of the BSG's Gut Microbiota for Health Expert Panel and chaired the Microbiology Society's "Unlocking the Microbiome " working group and the subsequent publication.



Marchesi J, Alexander J, Balarajah S, et al., 2023, Identification of a sub-clinical Salmonella spp. infection in a dairy cow using a commercially available stool storage kit, Animals, Vol:13, ISSN:2076-2615, Pages:1-11

Kragsnaes MS, Miguens Blanco J, Mullish BH, et al., 2023, Small intestinal permeability and metabolomic profiles in feces and plasma associate with clinical response in patients with active psoriatic arthritis participating in a fecal microbiota transplantation trial: exploratory findings from the FLORA trial, Acr Open Rheumatology, ISSN:2578-5745

Yip AYG, King OG, Omelchenko O, et al., 2023, Antibiotics promote intestinal growth of carbapenem-resistant Enterobacteriaceae by enriching nutrients and depleting microbial metabolites, Nature Communications, Vol:14, ISSN:2041-1723, Pages:1-20

Lo J, Cozzetto D, Alexander J, et al., 2023, Immune checkpoint inhibitor-induced colitis is mediated by polyfunctional lymphocytes and dependent on IL23 and IFNg, Nature Communications, ISSN:2041-1723

Gallacher DJ, Zhang L, Aboklaish AF, et al., 2023, Baseline azithromycin resistance in the gut microbiota of preterm born infants., Pediatr Res

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