Structural dynamics and transcriptomic analysis of Dehalococcoides mccartyi within a TCE-Dechlorinating community in a completely mixed flow reactor. (1st July 2019)

• Record Type: Journal Article
• Authors: Mao, Xinwei; Stenuit, Benoit; Tremblay, Julien; Yu, Ke; Tringe, Susannah G.; Alvarez-Cohen, Lisa
• Is Part Of: Water research. Volume 158(2019)
• Page Start: 146
• Page End: 156
• Publication Date: 2019-07-01
• Subjects: CMFR -- Dechlorination -- Community structure -- Transcriptomic analysis -- Dehalococcoides -- Functional robustness; CMFR -- Completely mixed flow reactors -- PCE -- Perchloroethene -- SRA -- Sequence read archive -- SRT -- Sludge retention time -- TCE -- Trichloroethene -- TMM -- Trimmed mean of M-values; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2019.04.038
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: A trichloroethene (TCE)-dechlorinating community (CANAS) maintained in a completely mixed flow reactor was established from a semi-batch enrichment culture (ANAS) and was monitored for 400 days at a low solids retention time (SRT) under electron acceptor limitation. Around 85% of TCE supplied to CANAS (0.13 mmol d −1 ) was converted to ethene at a rate of 0.1 mmol d −1, with detection of low production rates of vinyl chloride (6.8 × 10 −3 mmol d −1 ) and cis -dichloroethene (2.3 × 10 −3 mmol d −1 ). Two distinct Dehalococcoides mccartyi strains (ANAS1 and ANAS2) were stably maintained at 6.2 ± 2.8 × 10 8 cells mL −1 and 5.8 ± 1.2 × 10 8 cells mL −1, respectively. Electron balance analysis showed 107% electron recovery, in which 6.1% were involved in dechlorination. 16 S rRNA amplicon sequencing revealed a structural regime shift between ANAS and CANAS while maintaining robust TCE dechlorination due to similar relative abundances of D. mccartyi and functional redundancy among each functional guild supporting D. mccartyi activity. D. mccartyi transcriptomic analysis identified the genes encoding for ribosomal RNA and the reductive dehalogenases tceA and vcrA as the most expressed genes in CANAS, while hup and vhu were the most critical hydrogenases utilized by D. mccartyi in the community. Graphical abstract: Image 1 Highlights: Reductive dechlorination of TCE to ethene by a steady-state chemostat culture. Shift of microbial community from batch-fed to continuous exposure to low TCE. Community functional robustness ensures stable TCE-to-ethene reduction. Reductive dehalogenases tceA and vcrA show the highest functional gene expression. Selection of bio-marker genes for monitoring of TCE-contaminated groundwater plumes.