Characterization of Antarctic hydrocarbon-degrading bacteria capable of producing bioemulsifiers

During screening for biosurfactant-producing, n-alkane-degrading marine bac teria, two heterotrophic bacterial strains were isolated from enriched mixe d cultures, obtained from Terra Nova Bay (Ross sea, Antarctica) by using al iphatic and artomatic hydrocarbons as the principal carbon source. These gr am-positive, aerobic, cocci-shaped bacteria use a various number of organic compounds, including aliphatic hydrocarbons, volatile fatty acids, and bip henyl. During cultivation on n-alkanes as sole source of carbon and energy, all strains produced both an extracellular and cell-bound surface-active m ixture of trehalose lipids which reduced the surface tension of water from 72 mN/m to 32 mN/m. This class of glycolipids was found to be produced only by marine rhodococci. The 16S rRNA gene sequence analysis showed that both strains are members of the G+C rich gram-positive group of the phylum Prot eobacteria and was found to be almost identical to that of Rhodococcus fasc ians DSM 20669. The potential of these strains for in situ bioremediation o f contaminated cold marine environment is discussed in the present study.