Qilu University of Technology (Shandong Academy of Sciences), Ecology Institute, Shandong Provincial Key Laboratory of Applied Microbiology, 28789 East Jingshi Road, Jinan, 250103, China; Global Centre for Environmental Remediation, Faculty of Science, University of Newcastle, Callaghan, NSW, 2308, Australia.
Global Centre for Environmental Remediation, Faculty of Science, University of Newcastle, Callaghan, NSW, 2308, Australia.
Chemosphere. 2021 May;271:129566. doi: 10.1016/j.chemosphere.2021.129566. Epub 2021 Jan 7.
Nitrogen amendment is known to effectively enhance the bioremediation of hydrocarbon-contaminated soil, but the nitrogen metabolism in this process is not well understood. To unravel the nitrogen metabolic pathway(s) of diesel contaminated soil, six types of nitrogen sources were added to the diesel contaminated soil. Changes in microbial community and soil enzyme genes were investigated by metagenomics analysis and chemical analysis through a 30-day incubation study. The results showed that ammonium based nitrogen sources significantly accelerated the degradation of total petroleum hydrocarbon (TPH) (79-81%) compared to the control treatment (38%) and other non-ammonium based nitrogen amendments (43-57%). Different types of nitrogen sources could dramatically change the microbial community structure and soil enzyme gene abundance. Proteobacteria and Actinobacteria were identified as the two dominant phyla in the remediation of diesel contaminated soil. Metagenomics analysis revealed that the preferred metabolic pathway of nitrogen was from ammonium to glutamate via glutamine, and the enzymes governing this transformation were glutamine synthetase and glutamate synthetase; while in nitrate based amendment, the conversion from nitrite to ammonium was restrained by the low abundance of nitrite reductase enzyme and therefore retarded the TPH degradation rate. It is concluded that during the process of nitrogen enhanced bioremediation, the most efficient nitrogen cycling direction was from ammonium to glutamine, then to glutamate, and finally joined with carbon metabolism after transforming to 2-oxoglutarate.
氮素添加被认为可以有效地增强受烃类污染土壤的生物修复效果，但这一过程中的氮代谢途径还不是很清楚。为了揭示柴油污染土壤的氮代谢途径，向柴油污染土壤中添加了六种类型的氮源。通过 30 天的培养实验，利用宏基因组分析和化学分析的方法研究了微生物群落和土壤酶基因的变化。结果表明，与对照处理（38%）和其他非铵态氮改良剂（43-57%）相比，铵态氮源显著加速了总石油烃（TPH）的降解（79-81%）。不同类型的氮源可以显著改变微生物群落结构和土壤酶基因丰度。变形菌门和放线菌门被确定为修复柴油污染土壤的两个主要门。宏基因组分析显示，氮的首选代谢途径是从铵盐经谷氨酰胺转化为谷氨酸，控制这一转化的酶是谷氨酰胺合成酶和谷氨酸合成酶；而在硝酸盐添加中，由于亚硝酸还原酶的低丰度，亚硝酸到铵盐的转化受到抑制，从而降低了 TPH 的降解速率。结论是，在氮增强生物修复过程中，最有效的氮循环方向是从铵盐到谷氨酰胺，然后到谷氨酸，最后在转化为 2-酮戊二酸后与碳代谢结合。
