Activity evaluation and composition analysis of biosurfactants produced by an obligate cold-adapted bacterium...

The extreme environment of the Antarctic has endowed microorganisms with the ability to adapt to low temperature. These cold-adapted microorganisms can maintain high biological activity even at low temperatures. To acquire microbial resources that can be applied in pollution remediation in cold regions, we isolated cold-adapted oil-degrading bacteria from soil samples collected in Fields Island, Antarctica. Through the analysis of oil spreading, surface tension and oil emulsification tests, six biosurfactant producing bacteria were screened from 125 oil-degrading strains. A cold-adapted biosurfactant-producing bacterium, Pedobacter sp. NJ-S-72 showed the largest oil spreading and better emulsifying activity and surface tension reduction FTIR and HPLC-MS analysis indicated the main component was rhamnolipid like compounds in the biosurfactant products of this train. Although Pedobacter sp. NJ-S-72 exhibits growth across a broad temperature range of 5-20 °C, its biosurfactant production activity is highest at low temperatures (5 °C). This study identifies, for the first time, a species of obligate cold-adapted biosurfactant-producing bacterium which could serve as a microbial remediation agent under low-temperature environmental conditions.