Gregg S. Pettis

Professor
BMB Division

PhD: University of Missouri

Phone: 225-578‐2798 
Lab Phone: 225-578‐9110
Office: 642 Life Sciences Building
Lab: 614/615/617 Life Sciences Building
E-mail: gpettis@lsu.edu 

Website:  Coming Soon

Area of Interest

Research in my lab combines genetic, molecular biological and omics (genomic, transcriptomic, proteomic, phylogenomic) approaches towards identifying and elucidating mechanisms of pathogenesis in the bacterial genera Streptomyces, Vibrio and most recently Clostridium.

Streptomyces- In collaboration with the LSU AgCenter, we are studying regulation of production of the phytotoxin thaxtomin in Streptomyces plant-pathogenic species, particularly in the sweetpotato soil rot pathogen Streptomyces ipomoeae.  We are also using genomic and phylogenomic techniques to identify and characterize genes potentially involved in pathogenesis in Streptomyces plant-pathogens.

Vibrio- We are studying regulation of exopolysaccharide production in the human pathogen Vibrio vulnificus, including the mechanisms by which this bacterium undergoes  phase variation among virulent encapsulated, attenuated unencapsulated, and biofilm-proficient rugose forms.  We also recently described a novel phase variant form of the cholera pathogen Vibrio cholerae and completed an initial RNA seq-based transcriptomic analysis of smooth and rugose forms of this pathogen in order to reveal additional genes potentially important for biofilm production in this species.

Clostridium- Also in collaboration with the LSU AgCenter, we are studying plant-pathogenic Clostridium isolates that cause soft rot disease on sweetpotato and a variety of other vegetable crops.  The incidence of flooding-associated soft rot disease of sweetpotato in the southeastern United States has been on the rise in recent years.

Selected Publications

Pettis, G.S., and A.S. Mukerji.  2020. Structure, function and regulation of the essential virulence factor capsular polysaccharide of Vibrio vulnificus. Int. J. Mol. Sci. 21:3259; doi:10.3390/ijms21093259. 

daSilva, W., Yang, K.-T., Pettis, G.S., Soares, N.R., Giorno, R., and C.A. Clark. 2019. Flooding-associated soft rot of sweetpotato storage roots caused by distinct Clostridium isolates. Plant Dis. 103:3050-3056. 

Pettis, G.S. 2018. Spreading the news about the novel conjugation mechanism in Streptomyces bacteria. Environ. Microbiol. Rep. 10:503-510. 

Lambert, B., and G.S. Pettis.  2017. Cholera.  In Encyclopedia of Life Sciences (eLS) John Wiley & Sons, Ltd: Chichester, UK. https://onlinelibrary.wiley.com/doi/10.1002/9780470015902.a0027200 

Garrett, S.B., K.L. Garrison-Schilling, J.T. Cooke, and G.S. Pettis. 2016.  Capsular Polysaccharide Production and Serum Survival of Vibrio vulnificus are Dependent on Antitermination Control by RfaH. FEBS Lett. 590:4564-4572.

Lambert, B., M. Dassanayake, D.-H. Oh, S.B. Garrett, S.-Y. Lee and G.S. Pettis. 2016.  A Novel Phase Variant of the Cholera Pathogen Shows Stress-Adaptive Cryptic Transcriptomic Signatures.  BMC Genomics: 17:914.

Huguet-Tapia, J.C., T. Lefebure, J.H. Badger, D. Guan, G.S. Pettis, M.J. Stanhope, and R. Loria. 2016.  Genome content and phylogenomics reveal both ancestral and lateral evolutionary pathways in plant-pathogenic Streptomyces species. Appl. Environ. Microbiol. 82:2146-2155.