Centre for Environmental Sustainability and Remediation, School of Science, RMIT University, Bundoora, Victoria, 3083, Australia.
Environ Sci Pollut Res Int. 2020 Sep;27(25):31171-31183. doi: 10.1007/s11356-020-09339-2. Epub 2020 May 31.
Hydrocarbon degradation is usually measured in laboratories under controlled conditions to establish the likely efficacy of a bioremediation process in the field. The present study used greenhouse-based bioremediation to investigate the effects of natural attenuation (NA) and necrophytoremediation (addition of pea straw (PS)) on hydrocarbon degradation, toxicity and the associated bacterial community structure and composition in diesel-contaminated soil. A significant reduction in total petroleum hydrocarbon (TPH) concentration was detected in both treatments; however, PS-treated soil showed more rapid degradation (87%) after 5 months together with a significant reduction in soil toxicity (EC = 91 mg diesel/kg). Quantitative PCR analysis revealed an increase in the number of 16S rRNA and alkB genes in the PS-amended soil. Substantial shifts in soil bacterial community were observed during the bioremediation, including an increased abundance of numerous hydrocarbon-degrading bacteria. The bacterial community shifted from dominance by Alphaproteobacteria and Gammaproteobacteria in the original soil to Actinobacteria during bioremediation. The dominance of two genera of bacteria, Sphingobacteria and Betaproteobacteria, in both NA- and PS-treated soil demonstrated changes occurring within the soil bacterial community through the incubation period. Additionally, pea straw itself was found to harbour a diverse hydrocarbonoclastic community including Luteimonas, Achromobacter, Sphingomonas, Rhodococcus and Microbacterium. At the end of the experiment, PS-amended soil exhibited reduced ecotoxicity and increased bacterial diversity as compared with the NA-treated soil. These findings suggest the rapid growth of species stimulated by the bioremediation treatment and strong selection for bacteria capable of degrading petroleum hydrocarbons during necrophytoremediation. Graphical abstract.
烃类降解通常在实验室控制条件下进行测量，以确定生物修复过程在野外的可能效果。本研究采用基于温室的生物修复来研究自然衰减（NA）和腐植质修复（添加豌豆秸秆（PS））对污染土壤中石油烃降解、毒性及相关细菌群落结构和组成的影响。两种处理均检测到总石油烃（TPH）浓度显著降低；然而，PS 处理的土壤在 5 个月后表现出更快的降解（87%），同时土壤毒性（EC=91mg 柴油/kg）显著降低。定量 PCR 分析显示，PS 处理的土壤中 16S rRNA 和 alkB 基因数量增加。生物修复过程中观察到土壤细菌群落发生了重大变化，包括许多烃降解细菌的丰度增加。细菌群落从原始土壤中的α变形菌门和γ变形菌门优势转变为生物修复过程中的放线菌优势。在 NA 和 PS 处理的土壤中，两个属的细菌，即鞘氨醇单胞菌属和β变形菌属，占主导地位，这表明在培养期间土壤细菌群落发生了变化。此外，豌豆秸秆本身被发现含有丰富的烃降解群落，包括黄单胞菌属、无色杆菌属、鞘氨醇单胞菌属、红球菌属和微杆菌属。实验结束时，与 NA 处理的土壤相比，PS 处理的土壤表现出较低的生态毒性和较高的细菌多样性。这些发现表明，生物修复处理刺激了物种的快速生长，并对腐植质修复过程中能够降解石油烃的细菌进行了强烈选择。
