Journal Article
Applied and Environmental Microbiology, vol. 83, iss. 8, 2017
Authors
Yujie Men, Ke Yu, Jacob Bælum, Ying Gao, Julien Tremblay, Emmanuel Prestat, Ben Stenuit, Susannah G. Tringe, Janet Jansson, Tong Zhang, Lisa Alvarez-Cohen, Shuang-Jiang Liu
Abstract
ABSTRACT
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 putative draft genomes were binned from the metagenomes. At an early stage (2 days), more transcripts of genes in the
Veillonellaceae
bin-genome were detected in the metatranscriptome of the enrichment without exogenous cobalamin than in the one with the addition of cobalamin. 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 quantitative PCR (qPCR) analyses confirmed higher transcript abundances of those corrinoid biosynthesis genes in the enrichment without exogenous cobalamin than in the enrichment with cobalamin. Furthermore, the corrinoid salvaging and modification pathway of
Dehalococcoides
was upregulated in response to the cobalamin stress. This study provides important insights into the microbial interactions and roles played by members of dechlorinating communities under cobalamin-limited conditions.
IMPORTANCE
The key chloroethene-dechlorinating bacterium
Dehalococcoides mccartyi
is a cobalamin auxotroph, thus acquiring corrinoids from other community members. Therefore, it is important to investigate the microbe-microbe interactions between
Dehalococcoides
and the corrinoid-providing microorganisms in a community. This study provides systems-level information, i.e., taxonomic and functional compositions and dynamics of the supportive microorganisms in dechlorinating communities under different cobalamin conditions. The findings shed light on the important roles of
Veillonellaceae
species in the communities compared to other coexisting community members in producing and providing corrinoids for
Dehalococcoides
species under cobalamin-limited conditions.
