Organic solvent tolerance of Halobacterium sp. SP1(1) and its extracellular protease.

Halophilic archaea belonging to three different genera- Halobacterium, Haloarcula and Haloferax, were isolated from Kandla salt pans. The isolates had an optimum requirement of 25% NaCl for growth. Increase in organic solvent tolerance of isolates was observed at higher NaCl concentrations. Among the three isolates Halobacterium sp. SP1(1) was found to be more tolerant than Haloarcula sp. SP2(2) and Haloferax sp. SP1(2a). The extracellular protease of Halobacterium sp. SP1(1) showed higher solvent tolerance compared to the organism itself. The enzyme was highly tolerant to toluene, xylene, n-decane, n-dodecane and n-undecane, majority of which are frequently used in paints. These findings may help in understanding the mechanism of organic solvent tolerance in halophilic archaea and their application in antifouling coatings. Also, best to our knowledge the present study is the first report on organic solvent tolerance of haloarchaeal extracellular protease.