Project description:Recent interest in the ability of Desulfovibrio vulgaris Hildenborough to reduce, and therefore contain, toxic and radioactive metal waste, has made all factors that affect its physiology of great interest. Increased salinity constitutes an important and frequent fluctuation faced by D. vulgaris in its natural habitat. Using data from microarray experiments, as well as other laboratory analyses, we used a systems approach to explore the effects of excess NaCl on D. vulgaris. This study demonstrates that import of osmoprotectants such as glycine betaine and ectoine constitute the primary mechanism used by D. vulgaris to counter hyper-ionic stress. Several efflux systems also were highly up-regulated, as was the ATP synthesis pathway. Increase in both RNA and DNA helicases suggested that salt stress had affected the stability of nucleic acid base pairing. An immediate response to salt stress included up-regulation of chemotaxis genes though flagellar biosynthesis was down-regulated. Other down-regulated systems included lactate uptake permeases and ABC transport systems. The extensive NaCl stress analysis was compared with microarray data from KCl stress and unlike many other bacteria, D. vulgaris responded similarly to the two stresses. Keywords: Comparison of cells treated with either NaCl (250 mM) or KCl (250 mM) to untreated cells at times of 0, 30, 60, 120, and 240 min.