Cormac Gahan


  • 1990        BSc in Microbiology, National University of Ireland, Cork
  • 1996       PhD in Immunology & Immunology, National University of Ireland, Cork

Dr. Cormac Gahan graduated in 1996 with a PhD in Immunology and Microbiology from University College Cork. He has since published 114 peer-reviewed articles and book chapters in journals including PNASMolecular MicrobiologyInfection and ImmunityVaccine and Journal of Bacteriology. His current h-index is 43 on Google Scholar (40 on ISI) with total career citations of 5766 (Google Scholar).

Dr. Gahan led the Infectious Disease programme with Prof. Colin Hill within the Alimentary Pharmabiotic Centre from 2003-2013 and now leads the Bile Research Group within the APC Microbiome Institute with Dr. Susan Joyce. His research interests focus upon host-microbe signalling in the gut mediated via microbial bile acid metabolism (see Joyce et al., PNAS, 2014; Jones et al., PNAS, 2008 – 186 citations; Begley et al., 2005 – 445 citations). Dr. Gahan also has a long history of research work on the foodborne pathogen Listeria monocytogenes (in collaboration with Prof. Colin Hill) resulting in a number of key papers in the area (for example see Corr et al., PNAS, 2007 – 381 citations).

Recent work has also examined the use of live L. monocytogenes and L. lactis vectors as gene and protein delivery platforms for novel vaccination and therapeutic approaches. This work has been carried out in collaboration with Dr. Mark Tangney at the Cork Cancer Research Centre and Dr. Brendan Griffin in the School of Pharmacy, UCC.

In addition to his role as a funded researcher and PI in the APC he is funded by further grants from Science Foundation Ireland, the Health Research Board and the EU (FP7 and H2020).

Dr. Gahan is currently on the Editorial Board of the Journal of Pathogens and Applied and Environmental Microbiology and was on the editorial board of Journal of Applied Microbiology & Letters in Applied Microbiology from 2004-2010. He is a regular reviewer for numerous journals (including PNAS, Plos One, Microbiology, J. Bacteriol., AEM).

Dr. Gahan has given 26 invited presentations between 2008-2014 as well as numerous offered talks and posters.

Dr. Gahan directed the SFI funded UREKA summer school programme entitled Microbe-Host Interactions that provided laboratory training for 84 undergraduate students from 2006-2011.

Research Interests

  • Bile acids as mediators of host-microbe signalling in the gut
  • Development of live bacterial vaccine and DNA delivery vectors
  • Understanding microbial pathogenesis in gut pathogens (Listeria monocytogenesClostridium difficile)
  • Culture-independent approaches to understanding the gut microbiota

His research group is dedicated to understanding the molecular interactions between bacteria and the host in the gastrointestinal tract. The work has examined the pathogenesis of specific gut pathogens (in particular Listeria monocytogenes and Clostridium difficile) as well as the specific interactions that occur between gut commensals and the host organism. A complete understanding of the mechanisms governing host-pathogen interactions in the GI tract can be used to inform vaccine or DNA delivery strategies, to combat infections or to exploit the unique properties of these organisms as live vectors for the delivery of novel therapeutics. For example in collaboration with Dr. Mark Tangney at the Cork Cancer Research Centre they have recently exploited attenuated L. monocytogenes as a gene delivery vehicle for targeting tumour cells (van Pijkeren et al, 2010, Human Gene Therapy). In addition, benign L. lactis bacteria can be used to express a protein from L. monocytogenes that improves the ability of the organism to act as a vaccine delivery vector (in collaboration with Dr. Brendan Griffin; Bahey-el-din et al., 2008, Vaccine).

 L. monocytogenes shares much in common with normal harmless bacteria that reside as commensals in the human GI tract. his group has utilized culture-independent approaches (metagenomics) to examine one such activity (bile salt hydrolase (BSH)) that is abundant throughout the entire population of organisms in the GI tract (Jones et al., 2008, Proceedings of the National Academy of Sciences). More recent work in his group (with Dr. Susan Joyce) has demonstrated the significant impact exerted bybacterial BSH activity in the gut (Joyce et al. 2014, Proceedings of the National Academy of Sciences).  The work demonstrates the potential for gut bacteria to significantly alter host physiological parameters (including immune function, lipid metabolism and circadian rhythm) by coordinating changes to host bile acid profiles. Ongoing work in their Bile Research Group is further examining the impact of microbially-altered bile acid profiles upon disease states using appropriate models.

Current Research Funding & Grants:

  • EU FP7 Industry Academia Partnerships & Pathways grant.Co-ordinated and led by Dr. Mark Tangney, Cork Cancer Research Centre (CCRC) and with partners in Italy and Switzerland.
  • EU Horizon 2020 Initial training Network. 2014-2017.Co-ordinated and led by Dr. Pascal Piveteau, University of Dijon including partners from NUIGalway, University of Copenhagen and Wageningen University.
  • Health Research Board, Health Research Award. 2013-2016.Lead PI Dr. Cormac Gahan with co-PIs Dr. Susan Joyce and Prof Fergus Shanahan and collaborator Dr. Marcus Claesson.
  • Alimentary Pharmabiotic Centre (APC). SFI Centres Award. 2013-2019. Bile Acid Group (Targeted Project 4) led by Dr. Cormac Gahan and Dr. Susan Joyce.
  • Department of Agriculture & The Marine FIRM Programme. Dec 2012-2016. TransListeria
  • Translating fundamental research on Listeria monocytogenesfor the benefit of a multi-sectoral ready-to-eat food industry. Project led by Dr. Kieran Jordan, Teagasc, Moorepark. Budget to UCC (Dr. Cormac Gahan) is €345,996


Please see: 

Professional Activity

Please see: 



Cormac Gahan

Contact Details:


Principal Investigators

APC Microbiome Ireland

Biosciences Building, University College Cork, Ireland,