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

从紫贻贝消化腺中分离到4种石油降解菌，从紫贻贝栖息地附近的渔港海水中分离到3种石油降解菌。然后，我们试图表征它们并测量它们的石油降解率。[研究结果] 1.细菌特性：各种细菌均为非运动性杆状。最适生长温度为30℃。根据16 SrRNA基因的DNA序列、SDS-PAGE电泳带型和超微结构的观察，将各组中的细菌鉴定为食烷菌属（Alcanivorax sp.）。2.降解率：以重油干重的变化为指标，考察了7株食烷菌的降解能力。从海洋中提取的微生物降解率在10%~ 30%之间，从海水中提取的微生物降解率在10%以下。与不含重油的培养基相比，含有重油的培养基使细胞密度增加约10倍或更多。该结果表明这些细菌可以利用重油组分。3.油脂降解机理：我们观察到重油被Alcanivorax sp.的浓缩培养基乳化。SDS-PAGE显示最突出的组分条带是脂多糖，然后我们推测脂多糖作为生物表面活性剂用于降解。

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.