Understanding the influence of heavy water stress on the physiology of Salmonella Typhimurium.

The heavy isotope of water is used in understanding the physiology of bacteria. Deuterium (DO) reduces chemical reaction kinetics. In the present study, the survivability of the food-borne pathogen Salmonella Typhimurium grown in DO supplemented medium is studied under various stress conditions. The growth of S, Typhimurium was studied in rich (Luria Broth-LB) and minimal medium (M9) prepared in DO. The reduced growth rate of S. tTyphimurium in M9 (2.4 fold) as compared to that in LB (1.6 fold) was observed. S. tTyphimurium grown in DO supplemented medium was significantly more tolerant to heat and gamma radiation (1.2 fold), but was sensitive to extreme pH (both alkaline and acidic) and osmotic stress (10 fold). These results suggest that the change in the biological reaction kinetics in the cell due to DO may modify the stress tolerance of S. tTyphimurium. This is the first study carried out to understand how a bacterial system (S. Typhimurium) in DO responds to different stresses. This study suggests that investigations on bacterial physiology in DO supplemented medium helps in understanding the underlying mechanisms of stress tolerance.