The bioremediation of metolachlor in soil using Rhodospirillum rubrum after wastewater treatment
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Reliable and effective techniques for removing contaminants from soil are highly desirable. However, metolachlor residue bioremediation and soil fertility improvement by Rhodospirillum rubrum (R. rubrum) in effluent after wastewater treatment have not yet been investigated. The aims of this study were to investigate the feasibility of bioremediation of metolachlor residues in soil and soil fertility improvement by R. rubrum in effluent and to explain the mechanism that R. rubrum in effluent was induced to express the regulatory gene.
Materials and methods
Soybean processing wastewater was obtained from Harbin Soybean Products Machining Factory. Soil samples were the surface soil (0–30 cm) from campus (1.77 g/kg total N, 4.15 g/kg total P, 1.58 g/kg total K, 17 g/kg SOM, 0.07 g/kg SMBC). Cytochrome P450 monooxygenase regulatory gene, MAPKKKs gene, was measured by RT-PCR.
Results and discussion
Compared to control treatment, metolachlor was removed efficiently and soil fertility was remediated by effluent containing R. rubrum. The removal in concentrations reached 2.97 mg/L (99%). Soil organic matter (SOM) and SMBC were enhanced 42 times. Molecular analysis revealed that metolachlor induced cpm gene expression to synthesize cytochrome P450 monooxygenase through activating MAPKKKs gene in MAPK signal transduction pathway.
Bioremediation of metolachlor in soil and improvement of soil fertility using R. rubrum in effluent were feasible. Metolachlor, as environmental pressure, induced cpm gene expression to synthesize cytochrome P450 monooxygenase and to remove metolachlor through activating MAPKKKs, MAPKKs, MAPKs genes in MAPK signal transduction pathway.
KeywordsBioremediation cpm gene Effluent Metolachlor,R. rubrum Soil
The authors received financial support and basic scientific research service fees from the National Nature Science Fund for Distinguished Young Scholars of China (Grant No. 41625002), the National Natural Science Foundation Young of China (Grant No. 31700432), the National Natural Science Foundation of China (Grant No. 31700432; 31470550; 81500493; 31400386; 51778114), Natural Science Foundation of Guangdong Province (Grant No. 2015A030313098), Application Technology Research and Development Projects of Harbin (Grant No. 2016RAXXJ103), the MOA Modern Agricultural Talents Support Project of the Central University and Dalian Nationalities University (0113-20000101).
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