Microbiome assembly corresponding to different substrates influences the trichloroethylene dechlorination performance. Microbiome assembly corresponding to different substrates influences the trichloroethylene dechlorination performance

Dehalococcides has the ability to complete the reduction of cis-dichloroethene (cis-DCE) and vinyl chloride (VC) to ethene, which use hydrogen gas as its electron donor. However, Dehalococcoides lacks abilities to synthesize several growth factors such as cobamides. These nutrients must be exogenously provided to facilitate the growth in the axenic cultures, or endogenously obtained from co-existing populations via a complex network for exchanges of nutrients. In this study, we evaluated the effects of microbial community structures and microbial potential functions doing reductive dechlorination of trichloroethene (TCE) by adding three distinct electron donors: acetate, a simple substrate; emulsified oil, slow H2 releasing substrate; and molasses, rapid H2 releasing substrat;. The molasses as the substrate had highest maximum dechlorination rate, more completely dechlorination, and the highest growth rate of Dehalococcoides than the others during short-time test. The results of high-throughput sequencing of 16S rRNA gene showed that the molasses as the substrate influenced the microbiome dynamics differently from the acetate, and emulsified oil. Moreover, the substrate type relieves the selection pressure and drives communities to become more stochastic. As predicted, the molasses as the substrate had higher potential to synthesize vitamin B12, and can be a better substrates to stimulate the Dehalococcoides activity in the absence of external vitamin B12. The functional predictions of microbial assembling indicated the differential analysis of predicted metagenomes indicated the effects of anaerobic fermentation of different substrates, resulting in the distinctive microbiome functions. According to results of the reactor test conducted in this study, it appears that the differences in TCE dechlorination and Dehalococcoides activity with different substrates. Finally, This study provides information and indicators of microbial consortia related to carbon sources for anaerobic bioremediation of TCE-contaminated sites, which will help improve precise bioremediation technologies.