Shanquan Wang
Jianzhong He
Chaofeng Shen
Michael J. Manefield- 1Environmental Microbiome Research Center, School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-sen University, Guangzhou, China
- 2Department of Civil and Environmental Engineering, National University of Singapore, Singapore, Singapore
- 3Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, China
- 4School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, Australia
Editorial on the Research Topic
Organohalide respiration: New findings in metabolic mechanisms and bioremediation applications, Volume II
The massive production and use of organohalides resulted in their worldwide contamination in soil, sediment and other environmental matrices (He et al., 2021). Organohalide-respiring bacteria (OHRB)-mediated reductive dehalogenation not only represents a promising solution for remediation of sites contaminated by organohalides (Jugder et al., 2016; Atashgahi et al., 2018), but involves element cycling in both terrestrial and marine environments (Horna-Gray et al., 2022; Xu et al., 2022). Recent research progress in characterizing major OHRB and crystal structures of key functional enzymes provided critical insights into organohalide respiration of OHRB (Bommer et al., 2014; Payne et al., 2015; Kublik et al., 2016; Wang et al., 2018; Picott et al., 2022). Nonetheless, there are still many puzzles to be resolved for better mechanistic understanding and bioremediation applications. Therefore, this Research Topic was formulated in two volumes to solicit manuscripts related to organohalide-respiring bacteria, reductive dehalogenase (RDase) and associated electron transport chain, dehalogenating microbiome, and organohalide bioremediation. Given the success of Volume I of this Research Topic and the rapidly evolving subject area, Volume II was launched for the publication of new research findings and updated information. We selected four manuscripts for publication after a rigorous peer review process.
Organohalide-respiring bacteria
In a Dehalococcoides-containing enrichment culture, Zhao et al. reported extensive and even complete debromination of two commonly used polybrominated diphenyl ethers (PBDEs, i.e., BDE47 and BDE183). In addition, the debromination extent and rate of BDE183 could be enhanced by amendment of the BDE47. This study provides knowledge on new capabilities of Dehalococcoides and its potential in bioremediation of sites contaminated by both DBE47 and BDE183.
RDases and associated electron transport chains
Reductive dehalogenase is the key enzyme to catalyze halogen removal from organohalides. Based on both transcription and translation analyses, Cimmino et al. deciphered the stoichiometry of pceABCT individual gene products in OHRB of Firmicutes. Notably, in contrast to a previously proposed model, results showed the formation of a membrane-bound PceA2B that could be devoid of PceC. These results provide unprecedented insight into the electron-accepting complex in PCE-dechlorinating OHRB of the phylum of Firmicutes.
Organohalide bioremediation
Bioelectrochemical systems (BES) hold great potential for bioremediation of sites co-contaminated by organohalides and heavy metals. Matturro et al. employed both 16S rRNA gene amplicon sequencing and metagenomic analyses to elucidate the microbial interactions among Dehalococcoides, Methanobrevibacter and Methanobacterium for the efficient dechlorination of trichloroethene (TCE) and reduction of Cr(VI) in a BES. In addition, at sites contaminated with chlorinated ethenes, abiotic factors (e.g., iron sulfide minerals) could determine the fate of chloroethenes by affecting organohalide respiration of OHRB. Li et al. reported that FeS enhanced Dehalococcoides-mediated reductive dechlorination of TCE by formation of FeS nanoparticles and up-regulation of tceA transcription. These results could guide efficient bioremediation of sites contaminated by chlorinated ethenes and other contaminants.
With the success of the two volumes of this Research Topic, we would like to thank all the authors and reviewers for their valuable contributions. These papers significantly improve our understanding in organohalide-respiring bacteria and their electron transport chains, as well as in dehalogenating microbiome and bioremediation implications. Notably, several research gaps were also highlighted in this Research Topic, and awaited future studies: (1) contribution of microbial reductive dehalogenation to attenuation of organohalides in natural environments; (2) cycling of organohalides in varied environmental matrices and associated functional microorganisms and enzymes; (3) reciprocal interactions of the commonly co-existing abiotic processes with the OHRB-mediated reductive dehalogenation process. We hope that this collection of reviews and original research articles will be helpful for researchers and engineers seeking information on organohalide respiration and bioremediation applications.
Author contributions
All authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.
Funding
Topic editors acknowledge support of NSFC Grants 41922049 and 42161160306 to SW, the Ministry of Education in Singapore under Academic Research Fund Tier 2 Project MOE-00003301 to JH, NSFC Grant 21876149 to CS, and Australian Research Council Discovery Project DP190103640 to MM.
Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Publisher's note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
References
Atashgahi, S., Häggblom, M. M., and Smidt, H. (2018). Organohalide respiration in pristine environments: implications for the natural halogen cycle. Environ. Microbiol. 20, 934–948. doi: 10.1111/1462-2920.14016
Bommer, M., Kunze, C., Fesseler, J., Schubert, T., Diekert, G., Dobbek, H., et al. (2014). Structural basis for organohalide respiration. Science. 346, 455–458. doi: 10.1126/science.1258118
He, H., Li, Y., Shen, R., Shim, H., Zeng, Y., Zhao, S., et al. (2021). Environmental occurrence and remediation of emerging organohalides: a review. Environ. Pollut. 290, 118060. doi: 10.1016/j.envpol.2021.118060
Horna-Gray, I., Lopez, N. A., Ahn, Y., Saks, B., Girer, N., Hentschel, U., et al. (2022). Desulfoluna spp. form a cosmopolitan group of anaerobic dehalogenating bacteria widely distributed in marine sponges. FEMS Microbiol. Ecol. 98, fiac063. doi: 10.1093/femsec/fiac063
Jugder, B. E., Ertan, H., Bohl, S., Lee, M., Marquis, C. P., Manefield, M., et al. (2016). Organohalide respiring bacteria and reductive dehalogenases: key tools in organohalide bioremediation. Front. Microbiol. 7, 249. doi: 10.3389/fmicb.2016.00249
Kublik, A., Deobald, D., Hartwig, S., Schiffmann, C. L., Andrades, A., von Bergen, M., et al. (2016). Identification of a multi-protein reductive dehalogenase complex in Dehalococcoides mccartyi strain CBDB1 suggests a protein-dependent respiratory electron transport chain obviating quinone involvement. Environ. Microbiol. 18, 3044–3056. doi: 10.1111/1462-2920.13200
Payne, K. A., Quezada, C. P., Fisher, K., Dunstan, M. S., Collins, F. A., Sjuts, H., et al. (2015). Reductive dehalogenase structure suggests a mechanism for B12-dependent dehalogenation. Nature. 517, 513–516. doi: 10.1038/nature13901
Picott, K. J., Flick, R., and Edwards, E. A. (2022). Heterologous expression of active dehalobacter respiratory reductive dehalogenases in Escherichia coli. Appl. Environ. Microbiol. 88, e0199321. doi: 10.1128/aem.01993-21
Wang, S., Qiu, L., Liu, X., Xu, G., Siegert, M., Lu, Q., et al. (2018). Electron transport chains in organohalide-respiring bacteria and bioremediation implications. Biotechnol. Adv. 36, 1194–1206. doi: 10.1016/j.biotechadv.2018.03.018
Keywords: organohalide respiration, Dehalococcoides, electron transport chain, reductive dehalogenase, microbiome, bioremediation
Citation: Wang S, He J, Shen C and Manefield MJ (2022) Editorial: Organohalide respiration: New findings in metabolic mechanisms and bioremediation applications, Volume II. Front. Microbiol. 13:1112309. doi: 10.3389/fmicb.2022.1112309
Received: 30 November 2022; Accepted: 05 December 2022;
Published: 15 December 2022.
Edited and reviewed by: Eric Altermann, Massey University, New Zealand
Copyright © 2022 Wang, He, Shen and Manefield. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Shanquan Wang, 
wangshanquan@mail.sysu.edu.cn