耐盐植物虎尾草内生解烃细菌的筛选及其降解特性

Isolation and degradation characteristics of hydrocarbon-degrading endophytic bacteria from the salt-tolerant plant Chloris virgata

从耐盐植物中分离具有石油烃降解功能内生细菌并研究其降解特性,为内生细菌协同宿主植物修复石油污染盐渍化土壤提供基础。以黄河三角洲长期受石油污染重盐碱地生长的耐盐植物虎尾草为材料,分离出能以柴油为唯一碳源生长的内生细菌24株。通过柴油降解试验,筛选得到1株高效石油烃降解内生细菌BF04。经生理生化特性及16S r DNA同源序列分析,确定BF04为短小芽孢杆菌(Bacillus pumilus)。通过液体培养试验研究了BF04对不同烃的利用能力和对柴油的降解动力学特征。结果表明:BF04能够利用直链烷烃、支链烷烃和单环芳烃,不能利用多环芳烃和苯酚。BF04能降解柴油中大部分烷烃,其中对短链烷烃(n C11~n C23)降解率高于长链烷烃(n C24~n C27)。BF04对柴油降解可以用一级反应动力学模型表示。在含有3%Na Cl的液体培养基中,BF04具有较强的降解柴油能力,在修复石油污染高盐环境中具有一定的应用潜力。

The degradation characteristics of hydrocarbon-degrading endophytic bacteria isolated from salt-tolerant plants may provide the foundation for phytoremediation of petroleum-polluted saline soils using endophytic bacteria. Twenty-four strains of endophytic petroleum- degrading bacteria were isolated from the salt-tolerant plant Chloris virgata, which grows in a heavily saline-alkaline, crude oil-contaminat- ed environment in the Yellow River Delta, China. All 24 strains were able to utilize diesel oil as their sole carbon and energy source. Their a- bilities to degrade diesel oil were compared to screen one highly effective petroleum-degrading bacterium named BF04. The strain BF04 was identified as Bacillus pumilus based on physiological and biochemical characteristics, and 16S ribosomal DNA analysis. In addition, we studied the kinetic characteristics of diesel oil degradation and the capability of the strain to utilize different hydrocarbons. The results showed that strain BF04 could utilize straight-chain paraffin, branched paraffin, and mononuclear aromatics, but could not utilize phenol or polycyclic aromatic hydrocarbons. The degradation rate of diesel-oil short-chain n-alkanes（nC11-nC23 ） was relatively higher than that of long-chain n-alkanes（nC24-nC27） in the mineral salts（liquid） medium. The degradation of petroleum may be expressed using a first-or- der kinetic model. Moreover, the strain BF04 degraded diesel-oil effectively in the presence of 3% NaC1, indicating that strain BF04 has po- tential application in the bioremediation of petroleum-contaminated saline-alkaline soils.