Molecular Identification of a Halotolerant Bacterium NJ82 from Antarctic Sea Ice and Preliminary Study on Its Salt Tolerance

Abstract:

Halotolerant bacterium NJ82 was screened from 129 strains of Antarctic sea ice bacteria. Optimum salinity for the growth of this strain was 12% (W/V), and the highest salinity tolerance was 18% (W/V). The 16S rRNA gene sequences homology and phylogenetic analysis showed that strain NJ82 belonged to the genus Pseudoalteromonas. The contents of protein, proline, Malondialdehyde(MDA)and cell membrane permeability growing at different salinity were analyzed. When salinity was in the range of 3.3%-12.0% (W/V), the protein and praline content both greatly rose with the increase of salinity, but the MDA content and cell membrane permeability varied little. When the salinity was above 12.0 % (W/V), protein content decreased, while MDA contents and cell membrane permeability significantly increased with the increase of salinity. These changes of important physiological parameters would offer significant information to understand the adaptation mechanism of sea ice bacterium to high salinity conditions.

Key words:Salt tolerance, Sea ice bacteria, Antarctic, 16S rRNA