一株海草沉积物菲降解菌的筛选、鉴定和降解特性

Isolation, identification and degradation characteristics of a phenanthrene degrading bacteria derived from seagrass sediment

摘要:

【背景】多环芳烃(Polycyclic Aromatic Hydrocarbons，PAHs)是一类高毒性的有机污染物，在海洋环境尤其是沿海环境中广泛分布。海草床生态系统作为沿海环境的重要组成部分，深受环境污染等人类活动的影响而处于严重衰退的状态。微生物修复是修复环境中多环芳烃污染的重要途径，具有经济简便、环境友好和无二次污染等特点。【目的】从深圳市大亚湾的海草床沉积物中筛选获得高效多环芳烃降解菌，并分析其降解特性，从而探究海草床生态系统中多环芳烃污染物的微生物修复可行性。【方法】以多环芳烃菲为唯一碳源从海草床沉积物样品中筛选菌株，再通过形态学观察、生理生化实验和16S rRNA基因序列对筛选的菌株进行鉴定，并利用特定引物扩增多环芳烃降解的功能基因——双加氧酶(nidA)基因，最后通过培养实验分析该菌株对菲的降解特性。【结果】筛选出一株高效降解菲的菌株SCSIO 43702，经鉴定为玫瑰杆菌属(Roseovarius)的潜在新菌，并成功扩增得到双加氧酶相似(nidA like)基因；培养实验结果表明，玫瑰杆菌SCSIO 43702在10 d内对100 mg/L菲的降解率最高可达96%，而且其对菲的最适降解条件为：温度30 °C、pH值7.5和8.0、盐度3%。【结论】玫瑰杆菌SCSIO 43702凭借其良好的菲降解能力和较强的环境适应性，具有进一步被开发为微生物菌剂以用于多环芳烃污染修复的巨大潜力，为海草床生态系统中多环芳烃污染的微生物修复研究提供了理论依据和可利用的微生物资源。

关键词:多环芳烃，海草床生态系统，多环芳烃降解菌，双加氧酶(nidA)基因

Abstract:

[Background] Polycyclic aromatic hydrocarbons (PAHs) are highly toxic organic contaminants which are widely spread in the marine environment, especially in the coastal environment. As an important component of the coastal environment, seagrass ecosystems are under serious degradation status because of the effect of artificial activities including environmental pollutions. Microbial bioremediation has many advantages, such as cost-effective and environmentally friendly without secondary pollutions, and becomes the important way to restore PAHs-contaminated environments. [Objective] This study aimed to explore the feasibility of microbial remediation of PAHs-contaminants in seagrass ecosystems. Seagrass sediment from Daya Bay in Shenzhen City has been collected to isolate the effective PAHs-degrading bacterium, and the degrading characteristics of the strain have been analyzed. [Methods] The PAHs-degrading bacterium was isolated by phenanthrene as the sole carbon source, and the morphological observations, physiological and biochemical experiments and 16S rRNA gene sequences molecular analysis had been conducted for its identification. In the meanwhile, nidA gene, a functional gene for PAHs degradation, was amplified from the strain by specific primer. Finally, we used incubation experiments to analyze the strain’s degradation characteristics. [Results] A highly effective phenanthrene-degrading strain SCSIO 43702 was isolated and identified as a potentially novel species of the genus Roseovarius, and nidA gene was successfully amplified from Roseovarius SCSIO 43702. The result of incubation experiments showed that Roseovarius SCSIO 43702 could degrade 96% phenanthrene (100 mg/L) within ten days, and its optimal degrading conditions were as follows: the temperature at 30 °C, pH value at 7.5 or 8.0, salinity at 3%. [Conclusion] The bacterium Roseovarius SCSIO 43702 has high phenanthrene-degrading ability and environmental adaptability, these characteristics indicate the bacterium has great potential to be developed as microbial agents for PAHs bioremediation. All these findings in this study provide a theoretical basis and available microbial resource for bioremediation of PAHs-contaminants in the seagrass ecosystem.

Key words:polycyclic aromatic hydrocarbons (PAHs), seagrass ecosystem, PAHs-degrading bacteria, nidA gene