Study On The Biodegradation Of RDX By Rhodococcus

Nitrogen heterocyclic nitroamine compounds such as RDX and HMX have caused serious pollution of soil and groundwater.The biodegradation of nitrogen heterocyclic nitroamine compounds will be beneficial for environmental protection and restoration.However,related microorganisms present low tolerance to target compounds,and low degradation rates.And their biodegradation mechanism are still unclear.This study screened a Rhodococcus sp.strain with excellent RDX degrading ability.It is tolerable to RDX and is able to use RDX as the sole nitrogen source for growth.The initial RDX 17.8 mg/L was degraded to 6.68 mg/L after 33 h.However,at high RDX concentration(26.3 mg/L)and low RDX concentration(6.3 mg/L),the strain present poor growth rate and can hardly degrade RDX.This study also found that the growth of Rhodococcus sp.was inhibited under anaerobic conditions.This study also utilized genomics,proteomics and non-targeted metabonomics technologies to research the molecular mechanism of the RDX biodegradation by the strain.Genomics and comparative cluster analysis initially focused on 22 key nitrogen compound metabolism genes,4 key nitrogen compound transport genes,and 1 N metabolic pathway regulatory gene.Compared with the control group,differential proteomics found that the significantly increased proteins in the experimental group are mainly involved in the following metabolic processes: organic nitrogen biosynthesis metabolism,organic nitrogen conversion metabolism,organic nitrogen degradation metabolism,carboxyl compound metabolism;these metabolisms are the same as RDX Degradation metabolism is highly correlated.In non-targeted metabolomics studies,it was found that RDX as the only nitrogen source has a greater impact on the nitrogen metabolism pathway of strains.Compared with the control group,it was found that the content of 7 nitrogen-containing compounds was significantly increased in the experimental group.They were 3-aminobutyric acid,N,N-dimethylhistidine,2-aminoadipate,and 2-aminobutyric acid.Acid,dimethylisoxazine,carbazoline,bufenac.However,the expected RDX degradation intermediate metabolites were not detected in metabolomics studies.it is hard to figure out the complete catabolic pathway of RDX in this study.