Novel bacterial diversity is enriched with chloroperoxidase-reacted organic matter under anaerobic conditions

Fungal chloroperoxidases (CPOs) are one class of enzymes that produce natural organochlorides in soils. The microbial degradation of these organochlorides is not well known, though has implications for bioremediation, microbial ecology and natural chlorine and carbon cycling. In this study, Illumina-based 16S rRNA gene sequencing and real-time quantitative PCR (qPCR) was used to characterize the bacterial community enriched from an amendment of organic matter reacted with CPO under conditions conducive towards chlorination (CPO-OM). In total, 17 bacterial groups were enriched in triplicate microcosms inoculated with creek sediment and amended with CPO-OM. These bacterial groups were neither enriched with amendments of non-reacted organic matter extract, with or without oxidative stress induced by H2O2, nor with amendments of organic matter reacted with CPO under non-chlorinating conditions. Of these, only two represented genera with known organohalide respiring bacteria-Dehalogenimonas and Dehalobacter. The genus Acetobacterium was also found to be enriched but the other 14 groups of enriched bacteria do not currently have any close phylogenetically related isolates. This study highlights a gap in the current understanding of the microbiology involved in natural organochloride turnover and suggests that CPO-OM could be used for isolating and culturing strains from novel bacteria genera.