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株石油降解菌(ODB)，并从渔港周围海水中分离到3株石油降解菌为紫贻贝栖息地。[研究结果]1.特征：各种细菌均呈非游动杆状。其最适生长温度为30℃。根据16SrRNA基因的DNA序列、SDS-PAGE图谱和细微结构观察，各组的细菌种类均鉴定为Alcanivorax sp。SDS-PAGE分析表明，7株Alcanivorax sp.相似，但有一些细微的不同。根据这一结果，我们推测有7个Alcanivorax sp.是Alcanivorax sp.的独特种或菌株。2.降解率：通过与其孵育的重油干重的变化来检验它们对石油的降解能力。对虾的降解率在10%-30%左右，对海水的降解率在10%以下。与不加重油的培养基相比，加有重油的培养基细胞密度提高了10倍以上。这一结果表明这些细菌可以利用重油成分(S)。3.石油降解机理：用Alcanivorax sp.浓缩培养基乳化重油。SDS-PAGE显示最显著的组分带为脂多糖，推测该脂多糖在降解过程中起到了生物表面活性物质的作用。

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.