Project description:The aim of this study is to obtain a systems level understanding of the interactions between Dehalococcoides and corrinoid-supplying microorganisms by analyzing community structures and functional compositions, activities and dynamics in trichloroethene (TCE)-dechlorinating enrichments. Metagenomes and metatranscriptomes of the dechlorinating enrichments with and without exogenous cobalamin were compared. Seven draft genomes were binned from the metagenomes. At an early stage (2 d), more transcripts of genes in the Veillonellaceae bin-genome were detected in the metatranscriptome of the enrichment with exogenous cobalamin compared to the one without cobalamin addition. Among these genes, sporulation-related genes exhibited the highest differential expression when cobalamin was not added, suggesting a possible release route of corrinoids from corrinoid-producers. Other differentially expressed genes include those involved in energy conservation and nutrient transport (including cobalt transport). The most highly expressed corrinoid de novo biosynthesis pathway was also assigned to the Veillonellaceae bin-genome. Targeted qPCR analyses confirmed higher transcript abundances of those corrinoid biosynthesis genes in the enrichment without exogenous cobalamin. Furthermore, Dehalococcoides' corrinoid salvaging and modification pathway was upregulated in response to the cobalamin stress. This study provides important insights into the microbial interactions and roles of members of dechlorinating communities under cobalamin-limited conditions.
Project description:Dehalococcoides mccartyi obligately depends on organohalide respiration for energy conservation and growth. The genome of strain CBDB1 encodes 32 reductive dehalogenases, which enable the reductive dehalogenation of a broad range of halogenated compounds. It is one of the few strains able to respire chlorinated benzenes. The differential transcriptional response of the dehalogenase-encoding and –associated genes to halogenated aromatic compounds has so far not been studied on a genome-wide level. To understand the global transcriptional response to specific halogenated aromatic compounds, we analyzed and compared the transcriptomes during growth with 1,2,3- and 1,2,4-trichlorobenzene (TCB).
