Dehalococcoides mccartyi NIT01, a novel isolate, dechlorinates high concentrations of chloroethenes by expressing at least six different reductive dehalogenases

Masaki Asai; Naoko Yoshida; Toshiya Kusakabe; Mohamed Ismaeil; Takumi Nishiuchi; Arata Katayama

doi:10.1016/j.envres.2021.112150

Dehalococcoides mccartyi NIT01, a novel isolate, dechlorinates high concentrations of chloroethenes by expressing at least six different reductive dehalogenases

Environ Res. 2022 May 1:207:112150. doi: 10.1016/j.envres.2021.112150. Epub 2021 Oct 4.

Authors

Masaki Asai¹, Naoko Yoshida², Toshiya Kusakabe¹, Mohamed Ismaeil³, Takumi Nishiuchi⁴, Arata Katayama⁵

Affiliations

¹ Department of Civil and Environmental Engineering, Nagoya Institute of Technology (Nitech), Gokiso-Cho, Showa-Ku, Nagoya, Aichi, Japan.
² Department of Civil and Environmental Engineering, Nagoya Institute of Technology (Nitech), Gokiso-Cho, Showa-Ku, Nagoya, Aichi, Japan. Electronic address: yoshida.naoko@nitech.ac.jp.
³ Department of Environmental Engineering and Architecture, Graduate School of Environmental Studies, Nagoya University, Nagoya, 464-8603, Japan; Department of Microbiology, Faculty of Science, Ain Shams University, Cairo, Egypt.
⁴ Division of Integrated Omics Research, Kanazawa University, Ishikawa, Japan.
⁵ Department of Environmental Engineering and Architecture, Graduate School of Environmental Studies, Nagoya University, Nagoya, 464-8603, Japan.

PMID: 34619124
DOI: 10.1016/j.envres.2021.112150

Abstract

This study presents the isolation of a novel strain of Dehalococcoides mccartyi, NIT01, which can completely dechlorinate up to 4.0 mM of trichloroethene to ethene via 1,2-cis-dichroroethene and vinyl chloride within 25 days. Strain NIT01 dechlorinated chloroethenes (CEs) at a temperature range of 25-32 °C and pH range of 6.5-7.8. The activity of the strain was inhibited by salt at more than 1.3% and inactivated by 1 h exposure to 2.0% air or 0.5 ppm hypochlorous acid. The genome of NIT01 was highly similar to that of the Dehalococcoides strains DCMB5, GT, 11a5, CBDB1, and CG5, and all included identical 16S rRNA genes. Moreover, NIT01 had 19 rdhA genes including NIT01-rdhA7 and rdhA13, which are almost identical to vcrA and pceA that encode known dehalogenases for tetrachloroethene and vinyl chloride, respectively. We also extracted RdhAs from the membrane fraction of NIT01 using 0.5% n-dodecyl-β-d-maltoside and separated them by anion exchange chromatography to identify those involved in CE dechlorination. LC/MS identification of the LDS-PAGE bands and RdhA activities in the fractions indicated cellular expression of six RdhAs. NIT01-RdhA7 (VcrA) and NIT01-RdhA15 were highly detected and NIT01-RdhA6 was the third-most detected. Among these three RdhAs, NIT01-RdhA15 and NIT01-RdhA6 had no biochemically identified relatives and were suggested to be novel functional dehalogenases for CEs. The expression of multiple dehalogenases may support bacterial tolerance to high concentrations of CEs.

Keywords: Chloroethene; Dehalococcoides mccartyi; Reductive dehalogenase.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biodegradation, Environmental
Chloroflexi* / genetics
Chloroflexi* / metabolism
Dehalococcoides
RNA, Ribosomal, 16S / genetics
Trichloroethylene* / metabolism
Vinyl Chloride* / chemistry
Vinyl Chloride* / metabolism

Substances

RNA, Ribosomal, 16S
Trichloroethylene
Vinyl Chloride

Supplementary concepts

Dehalococcoides mccartyi