Exogenous vitamin B12 alleviated inhibition of salinity on anaerobic dichloromethane degradation by reducing cofactor-related constraints and reshaping community functional potential.

Authors

Jieyi Liu, Yixiao Tan, Xuan Fan, Sikai Xie, Xiangyang Xu, Liang Zhu

Published in

Journal of hazardous materials. Volume 514. Pages 142823. Jun 27, 2026. Epub Jun 27, 2026.

Abstract

Dichloromethane (DCM) frequently co-occurs with high salinity in industrial wastewater, imposing dual stress on anaerobic treatment. However, how anaerobic DCM degraders respond to salt stress and whether exogenous vitamin B12 (VB12, a key cofactor in DCM transformation) can facilitate DCM degradation remain poorly understood. Here, we established long-term enrichments (>800 days) of DCM-degrading consortia under non-saline and salt-stressed conditions (10 g/L NaCl) to investigate how VB12 affected degradation performance, community assembly, and functional potential. Salt stress significantly inhibited DCM degradation, reducing the maximum degradation rate by 71.5%, whereas VB12 substantially alleviated this inhibition and increased the degradation rate to 55.9% of the non-saline control. Metagenomic and co-occurrence network analyses indicated that salinity drove community reassembly and niche differentiation, linking DCM degraders, methanogens/homoacetogens, and fermenters within an inferred producer-cooperator-cross-feeder framework that maintained community stability under salt stress. Functional analyses showed that VB12 was associated with shifts in community functional potential toward hydrogenotrophic/acetoclastic methanogenesis and osmoadaptive metabolism, supporting stress adaptation under saline conditions. Further analysis of the mec (methylene chloride catabolism) cassette suggested that VB12 likely reduced cofactor-related constraints and reinforced downstream product-consuming functions, thereby contributing to the enhanced degradation performance. Notably, a previously uncharacterized Dehalobacteriaceae MAG, D_MAG.168, emerged as a dominant candidate DCM degrader under salt stress. Overall, these findings provide insight into the functional responses of DCM-degrading consortia to VB12 supplementation under salt stress and support the further development of VB12-assisted bioaugmentation strategies for DCM-contaminated saline industrial wastewater.

PMID:
42378762
Bibliographic data and abstract were imported from PubMed on 01 Jul 2026.

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