Microbiota-Derived Hydrogen Fuels Salmonella Typhimurium Invasion of the Gut Ecosystem

Lisa Maier, Rounak Vyas, Carmen Dolores Cordova, Helen Lindsay, Thomas Sebastian Benedikt Schmidt, Sandrine Brugiroux, Balamurugan Periaswamy, Rebekka Bauer, Alexander Sturm, Frank Schreiber, Christian von Mering, Mark D. Robinson, Bärbel Stecher, and Wolf-Dietrich Hardt. Cell Host Microbe. (2013) 14, 641–651.

Speaker: Chao-Hui Weng (翁肇徽)                              Time: 14:00~15:00, May. 21, 2014

Commentator: Dr. I-Hsiu Huang (黃一修 老師) Place: Room 601

Abstract:

The microbiota facilitate efficient breakdown of complex diet- and host-derived carbohydrates to short-chain fatty acids (SCFAs), hydrogen (H₂), and carbon dioxide. They limit nutrient availability and prohibits growth of most newly arriving bacteria. However, the human food-borne pathogen Salmonella Typhimurium (S. Tm) can grow up in this nutrient-depleted environment and cause disease. The authors wanted to know why S. Tm can colonize in intestinal. They constructed a set of 500 S. Tm transposon mutants and infected a mouse model for Salmonella diarrhea ( LCM mice ) (1). They found S. Tm hyb hydrogenase can power microbial growth by facilitating consumption of hydrogen, a central intermediate of microbiota metabolism (2). In competitive infection experiments, the hyb mutant (S. Tm^hyb which lacks all structural genes of the hyb hydrogenase) displayed reduced growth early in infection compared to the wild-type strain. Next, the authors investigated the role of the resident microbiota in hyb-dependent gut ecosystem invasion. The microbiota produce H₂ should be required for hydrogen-dependent pathogen growth. Indeed, the competitive growth defect of S. Tm^hyd was lost when the host microbiota was disrupted by antibiotic pretreatment. Additionally, introducing H₂-consuming bacteria into the microbiotainterfered with hyb-dependent S. Tm growth. In conclusion, H₂ could be exploited by S. Tm for gut ecosystem invasion. The molecular understanding of the gut ecosystem invasion phase might reveal unique opportunities for thwarting pathogen colonization right from the beginning.

References:

1.         Stecher, B., and Hardt, W.D. (2011). Mechanisms controlling pathogen colonization of the gut. Curr. Opin. Microbiol. 14, 82–91.

2.         Maier, R.J., Olczak, A., Maier, S., Soni, S., and Gunn, J. (2004). Respiratory hydrogen use by Salmonella enterica serovar Typhimurium is essential for virulence. Infect. Immun. 72, 6294–6299.