低分子有机酸对土壤中菲降解及细菌群落结构的影响

Effects of low-molecular-weight organic acids on the degradation of phenanthrene and bacterial community structure in soil

多环芳烃是一类普遍存在于环境中的持久性有机污染物,其通过食物链进入生态系统,直接危害人类健康和整个生态系统的安全。为探讨低分子有机酸对土壤中菲降解及细菌群落结构的影响,通过室内培养的方式研究了在添加不同种类有机酸处理下第0—180天土壤中菲含量的变化状况,并采用高通量Illumina Miseq技术分析了土壤细菌群落种类和数量的变化特征。结果表明,低分子有机酸对于土壤中菲的降解有明显的促进作用,由一级动力学方程得出乙酸对菲降解的促进作用最明显。从细菌群落结构来看,土壤细菌的数量及其多样性或许不是导致土壤菲降解的主要因素,反而特定的菲降解菌的丰度对菲降解有重要影响。添加低分子有机酸减少了细菌OTU数及细菌菌群多样性,但增加了PAHs降解菌的丰度。随着时间推移细菌总OTU数呈现下降趋势,独有种类数均呈现出先增长后下降的趋势。检测到了6种典型的菲降解菌,分别为:Bacillus、鞘氨醇单胞菌属、Massilia、Azospirillum、Burkholderia paraburkholderia、红球菌。研究结果可为多环芳烃污染土壤的植物修复提供基础数据和科学参考。

Polycyclic aromatic hydrocarbons(PAHs)are common persistent organic environmental pollutants,which enter the ecosystem through the food chain and directly endanger human health and the safety of the entire ecosystem.To investigate effects of low molecular weight organic acids on degradation of phenanthrene and bacterial community structure in soil,changes in soil phenanthrene content during 0—180 d after addition of different organic acids were assessed via variations in indoor culture characteristics of soil bacterial community types and quantities via high throughput Illumina Miseq.Consequently,addition of low molecular weight organic acids significantly promoted phenanthrene degradation in soil,and the first order reaction kinetids revealed that acetic acid had the most significant effect on phenanthrene degradation.Considering the bacterial community structure,addition of low molecular weight organic acids reduced the number of operational taxonomic units(OTUs)and the diversity of bacterial flora but increased the abundance of PAH degrading bacteria.The total number of bacterial OTUs displayed a decreasing trend with time,and the number of unique species initially displayed an increasing trend,followed by a decreasing trend.Six typical phenanthrene degrading bacteria were detected:Bacillus,Sphingomonas,Massilia,Azospirillum,Paraburkholderia,and Rhodococcus.These results provide a basis and a scientific reference for phytoremediation of PAHs contaminating soil.