Isolation, Characterization and Growth Kinetics of Chaotrope Induced Water Stress Tolerant Bacteria from Soils of Thar Desert

Chaotropic compounds that freely traverse biological membranes and do not affect turgor are powerful mediators of water stress. The present study was initiated to isolate, identify and characterize the Chaotrope tolerant bacteria from soil of Thar Desert. Bacteria were isolated from soil samples, collected from the surface of sand dunes, suspended in water contained 2.5 x 106 bacteria g-1 of soil while alcohol suspended soil had 4.4 x 104 bacteria g-1. The eleven bacterial isolates studied, for the tolerance was found tolerant to 10 % of alcohol, 14 % NaCl and 26 % glycerol and 9 out of 11 isolates were found to be gram positive. More than 50 % of isolates belonged to Bacillus species while Cornybacterium, Acinobacter, Aeromonas and Staphylococcus were also present. Growth kinetic studies revealed that under highly stressed conditions of alcohol and temperature, the generation time was reduced as compared to generation time in plain medium. A rise in incubation temperature and concentration of alcohol added in growth medium resulted in reduction in bacterial population. All Chaotropic solute tolerant bacteria were also tolerant to water stress induced by Halotropes and Kosmotrophes. This study suggests that non saline soil /sand dunes may be a common source for the isolation of bacteria tolerant to Chaotropic, Halotropic and Kosmotropic solutes up to a greater extent, and might help to resolve the general strategy adopted by microbes to thwart desiccation induced by various types of solutes.