John W. Foster, Ph.D.

Phone: (251) 460-6323
FAX: (251) 460-7931


Genetic regulatory networks and physiology of E. coli, Shigella, Salmonella and Vibrio

Dr. John W. Foster, Professor, received his Ph.D. in Microbiology from Hahnemann University College of Medicine (now part of Drexel University) in Philadelphia in 1979 and carried out his postdoctoral studies at Georgetown University.  Dr. Foster was honored in Who's Who in American Universities and Colleges in 1978, was named 1994 Hahnemann University Alumnus of the year, and received the 2007 Southeastern ASM branch “Robert Eagon Award” for accomplishments in microbial physiology.  He has served in the American Society for Microbiology as the Chair of Division K (Microbial Physiology and Metabolism) and as an invited ad hoc member of the Microbial Physiology and Bacterial Pathogenesis Study Sections for the National Institutes of Health (NIH).  His scholarly work includes over 100 peer-reviewed articles, 4 editions of a textbook on microbial physiology (coauthored by Albert G. Moat and Michael P. Spector), 3 editions of a textbook for undergraduate majors entitled "Microbiology: An Evolving Science" coauthored by Joan Slonczewski, PhD, Kenyon College, Ohio, and a new textbook for Allied Health majors called "Microbiology: The Human experience".  Dr. Foster has mentored 14 doctoral students and 16 post-doctoral fellows in studies designed to reveal the molecular strategies used by bacterial pathogens to survive stress.


Research Summary

The enteric pathogens Salmonella enterica, Shigella, and E. coli 0157:H7 face daunting odds during their voyages in the natural environment and through an infected host. After ingestion, for example, they must be prepared to meet extremely acidic conditions in the stomach. The more acid resistant an organism is, the more likely it can survive passage through the gastric acid barrier and ultimately cause disease. Our laboratory has discovered critical adaptive responses used by these organisms to survive acidic environments found in the stomach. These responses are induced when cells are shifted to mild acid conditions (pH 5 to pH 6), but once engaged they protect the organisms against strong acid conditions (pH 2 to pH 3). We are investigating these responses at the biochemical, genetic and molecular levels and have discovered that each organism uses elaborate genetic regulatory networks to control acid resistance.

A major question we are asking is how cells "sense" changes in proton concentration during adaptation, and subsequently transmit that signal to the transcriptional/translational machinery. The results of these studies will provide new insights into how cells control their internal pH, repair damage to macromolecules, and modulate gene expression upon recognizing imminent threats to survival. We have also discovered a link between the virulence plasmid of Shigella and the control of acid resistance.

In a separate project, we are examining the marine microbe Vibrio vulnificus and how it synthesizes and utilizes a growth factor. V. vulnificus is a pathogenic microbe commonly found in oysters. It can cause a severe, life-threatening disease in immunocompromised individuals who consume uncooked oysters. Work is underway to characterize the pathway used to synthesize this growth factor and to elucidate the molecular response to this compound.


Books Published



Microbiology: The Human Experience. 2015. Preliminary edition. J.W. Foster, Z. Aliabadi, and J.L. Slonczewski. WW Norton Publishing, New York, NY.




Microbiology: An Evolving Science.  2017.  4th edition.  J.L. Slonczewski and J.W. Foster.  WW Norton Publishing, New York, NY.




Microbial Physiology.  2002. 4th edition. A.G. Moat, J.W. Foster, M.P. Spector.  Wiley-Liss, Inc., New York, NY.


Recent Publications

Click here for a list of recent publications


Email Newsletters

Connect With Us