Oil Degrading Ability and Characterization of Oil Degrading Bacteria Isolated from Digestive Gland in Mytilus galloprovincialis.

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We have isolated 4 kinds of oil degrading bacteria(ODB) from the digestive gland of Mytilus galloprovincialis and 3 kinds of ODB from the sea water around fishery harbors are habitats of M.galloprovincialis. Then we tried to characterize them and to measure their oil degradation rate.【RESEARCH RESULTS】1.Characterization : All kinds of bacteria showed non-motile rod shape. Optimum growth temperature of these bacteria was 30℃. From DNA sequence of the 16SrRNA gene, band-pattern of SDS-PAGE and the observation of fine structures, the species of bacteria in each group were identified as Alcanivorax sp. SDS-PAGE showed that the band-patterns of 7 Alcanivorax sp. were similar, but there were some minor differences. From this result, we speculated that 7 Alcanivorax sp. are distinct species or strains of Alcanivorax sp. 2.Degradation rates : Their abilities to degrade oil were examined by the change in the dry weight of the heavy oil with which they were incubated. The degradation rates of bacteria from M.galloprovincialis were about 10%-30%, and the degradation rates of bacteria from the sea water were below 10%. The culture medium with heavy oil increased cell densities about 10 times or more in comparison with it without heavy oil. This result indicates that these bacteria can utilize heavy oil component(s). 3.Mechanisms of oil degradation : We have observed the heavy oil was emulsified by the concentrated culture medium of Alcanivorax sp. SDS-PAGE showed that the most prominent component band was a lipopolysaccharide, and then we have speculated that the lipopolysaccharide acts as a bio-surfactant for the degradation.