一株海洋石油降解菌的鉴定及表面疏水性研究

Identification and Study on Surface Hydrophobicity of a Marine Oil-Degrading Bacteria

  • 摘要: 微生物表面疏水性是影响其吸收和降解疏水性有机物质的主要因素之一。提高微生物表面疏水性有助其黏附于石油烃表面,从而有效减少石油烃的传质距离,提高其生物可利用性。从浙江省舟山市定海港口近岸石油污染的表层海水中,通过富集培养和分离纯化,筛选获得1株能以石油烃为唯一碳源且具有表面疏水性的菌株,并对菌株进行生理生化鉴定及16S rRNA 基因序列进化分析;研究培养时间、盐度、底物、表面活性剂等对菌株表面疏水性的影响。结果表明,该菌株属于假单胞菌属(Pseudomonas),与副乳假单胞菌(Pseudomonas paralactis)亲缘关系最近,命名为H2菌株;在对数生长期和稳定期菌株表面疏水性随培养时间的增加逐渐提高,在衰老期则随培养时间的增加逐渐降低;培养基盐度升高会降低菌株表面疏水性;以疏水性柴油为唯一碳源培养的菌株疏水性远高于以亲水性葡萄糖作为唯一碳源的;在菌株培养过程中加入表面活性剂会使菌株的表面疏水性发生改变,非离子表面活性剂Tween20、Tween80分别在质量浓度为30 mg/L、14 mg/L时,可提高菌株H2的表面疏水性;而阴离子表面活性剂鼠李糖脂、两性离子表面活性剂卵磷脂则降低了菌株H2的表面疏水性。

     

    Abstract: The surface hydrophobicity of microorganisms is one of the main factors affecting the absorption and degradation of hydrophobic organic matter. Improving the surface hydrophobicity of microorganisms can help them adhere to the surface of petroleum hydrocarbon, thus effectively reducing the mass transfer distance of petroleum hydrocarbon and improving its bioavailability. A strain with surface hydrophobicity that can use petroleum hydrocarbon as the only carbon source was isolated through enrichment culture from the polluted seawater of Dinghai Port in Zhoushan City. The physiological and biochemical identification and 16S rRNA gene sequence evolution analysis of the strain were conducted. The effects of incubation time, salinity, substrate and surfactants on the surface hydrophobicity of this strain were studied. The results showed that this strain belonged to the genus Pseudomonas, which was the closest relative to Pseudomonas paralactis, and was named as strain H2. The surface hydrophobicity increased with the increase of culture time when the strain was in logarithmic growth and stable stages. In the aging stage, the surface hydrophobicity decreased gradually with the increase of culture time. The increase of medium salinity reduced the surface hydrophobicity of the strain. When the hydrophobic diesel oil was used as the only carbon source, the surface hydrophobicity of the strain was much higher than that of hydrophilic glucose. The surface hydrophobicity of strain H2 was changed by adding surfactants in the culture process. The surface hydrophobicity was improved when non-ionic surfactants of Tween20 and Tween80 were added at the mass concentration of 30 mg/L and 14 mg/L, respectively. However, the anionic surfactant (rhamnolipid) and ampholytic surfactant (lecithin) reduced the surface hydrophobicity of strain H2.

     

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