Biodegradation Of 1,2,3-Trichloropropane And Evolutionary Of Microbial Community In Water

1,2,3-trichloropropane?TCP?is a non-natural,biodegradation-recalcitrant and toxic compound that is widely used in industrial and agricultural production.A few type of research have been confirmed aimed at establishing the possibilities for biodegradation and bioremediation of TCP.Furthermore it is generally believed that TCP can be transformed in a cometabolic manner.In order to study the mechanism of TCP degradation and the changes in the microbial communitis in polluted water,sampled from aquiferas of chlorinated hydrocarbon site in Shanghai in May 2019 and enriched the microorganisms.Combining GC-MS used to test concentrations of TCP and degradation products with molecular biology technology and bioinformatics to analyze the degradation mechanism and degradation kinetics of TCP and microbial evolution in the experiment.The results were:?1?The conditions for degradation of TCP were TCP initial concentration of 10mg/L,pH of about 7.0 and a culture temperature of 30°C.The degradation process of TCP followed the zero-order cometabolic degradation,and the degradation rate constant is about 2 mg/?L?d?.The intermediate product foud was 3-chloropropene.It is deducted that the degradation mechanism of TCP is:yeast extract?organic matter?produces H₂ through anaerobic fermentation.These bacteria utilize H₂ as the electron donor and TCP as the electron acceptor to produce the intermediate product 3-chloropropene.In the whole reaction process,microorganisms use sulfate as the electron acceptor and oxidize yeast extract to provide energy.The sulfide produced by sulfate reduction reacts with the intermediate degradation product 3-chloropropene to form allyl mercaptan.?2?High throughput sequencing method was used to analyze microbial diversity and community structure.Bacteroidetes,Firmicutes,and Proteobacteria are the main phylum.Among them,the abundance of Bacteroidetes gradually increases with the progress of TCP degradation experiments,the proportion of Firmicutes does not change,and the proportion of Proteobacteria gradually decreases.Macellibacteroides,Fusibacter,and Pseudomonas are the main genus.Among them,the abundance of Macellibacteroides gradually increases with the progress of TCP degradation experiments,the proportion of Fusibacter does not change,and the proportion of Pseudomonas gradually decreases.?3?The functional genes related to the research of TCP degradation are mainly sulfur metabolism,chloroalkane and chloroalkene degradation.Sulfur metabolism was relatively stable with the progress of TCP degradation experiments.Chloroalkane and chloroalkene degradation had the highest abundance when TCP began to degrade,while in other periods were relatively stable.