Isolation and Characterization of a Biosurfactant Producing Strain Planococcus sp. XW-1 from the Cold Marine Environment

One cold-adapted strain, named Planococcus sp. XW-1, was isolated from the Yellow Sea. The strain can produce biosurfactant with petroleum as sole source of carbon at low temperature (4 degrees C). The biosurfactant was identified as glycolipid-type biosurfactant species by thin-layer chromatography (TLC) and Fourier transform infrared spectroscopy (FTIR). It reduced the surface tension of water to 26.8 mN/m with a critical micelle concentration measurement of 60 mg/L. The produced biosurfactant possesses high surface activity at wide ranges of temperature (-18-105 degrees C), pH values (2-12), and salt concentrations (1-18%). The biosurfactant exhibited higher surface activity and higher growth rate of cells with hexadecane and diesel as carbon source. The strain Planococcus sp. XW-1 was also effective in degrading crude oil, after 21 days of growth at 4 degrees C in medium with 1% crude oil and 1% (v/v) bacteria broth, 54% of crude oil was degraded. The results suggest that Planococcus sp. XW-1 is a promising candidate for use in the bioremediation of petroleum-contaminated seawater in the Yellow Sea during winter. This study reported for the first time that Planococcus isolated from the Yellow Sea can produce biosurfactant using petroleum as the sole carbon source at low temperature (4 degrees C), showing its ecological role in the remediation of marine petroleum pollution.