Isolation and characterization of a protease-producing novel haloalkaliphilic bacterium Halobiforma sp. strain BNMIITR from Sambhar lake in Rajasthan, India

摘要

A novel haloalkaliphilic bacterium designated as strain BNMIITR was isolated from a soil sample collected from Sambhar lake, Rajasthan, in northern India. Colonies of the isolated strain were dark orange and comprised Gram-negative bacilli; there was a slight pleomorphism towards the stationary phase of growth. Experiments revealed that the isolate can grow in the range of 2–5?M NaCl, pH?6–11 and 18–55?°C, with optimum growth observed at 3?M NaCl, pH?8–8.5 and 45?°C. No growth was observed in culture medium without NaCl. The isolate showed no requirement for magnesium sulphate heptahydrate (MgSO4.7H2O) for growth. Major cellular fatty acids were C 14:0, C 15:0 iso, C 15:0 anteiso, C 16:0, C 17:0 iso, C 17:0 anteiso and C 20:2 w6, 9c. The result of 16S rRNA gene sequence analysis showed 98?% sequence similarity with Halobiforma lacisalsi and Hbf. haloterrestris. Halobiforma sp. strain BNMIITR showed resistance towards several antibiotics and produced an extracellular alkaline protease. The crude enzyme was found to be active in broad range of alkaline pH and temperature (30–80?°C).