Laboratory of Microbiology, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, PR China.
FEMS Microbiol Ecol. 2022 Jul 21;98(8). doi: 10.1093/femsec/fiac073.
Organohalide respiration (OHR), catalysed by reductive dehalogenases (RDases), plays an important role in halogen cycling. Natural organohalides and putative RDase-encoding genes have been reported in Aarhus Bay sediments, however, OHR has not been experimentally verified. Here we show that sediments of Aarhus Bay can dehalogenate a range of organohalides, and different organohalides differentially affected microbial community compositions. PCE-dechlorinating cultures were further examined by 16S rRNA gene-targeted quantitative PCR and amplicon sequencing. Known organohalide-respiring bacteria (OHRB) including Dehalococcoides, Dehalobacter and Desulfitobacterium decreased in abundance during transfers and serial dilutions, suggesting the importance of yet uncharacterized OHRB in these cultures. Switching from PCE to 2,6-DBP led to its complete debromination to phenol in cultures with and without sulfate. 2,6-DBP debrominating cultures differed in microbial composition from PCE-dechlorinating cultures. Desulfobacterota genera recently verified to include OHRB, including Desulfovibrio and Desulfuromusa, were enriched in all microcosms, whereas Halodesulfovibrio was only enriched in cultures without sulfate. Hydrogen and methane were detected in cultures without sulfate. Hydrogen likely served as electron donor for OHR and methanogenesis. This study shows that OHR can occur in marine environments mediated by yet unknown OHRB, suggesting their role in natural halogen cycling.
有机卤化物呼吸（OHR），由还原脱卤酶（RDases）催化，在卤素循环中起着重要作用。奥胡斯湾沉积物中已报道了天然有机卤化物和推测的 RDase 编码基因，但尚未通过实验验证 OHR。在这里，我们表明奥胡斯湾沉积物可以脱卤化一系列有机卤化物，并且不同的有机卤化物对微生物群落组成产生了不同的影响。通过 16S rRNA 基因靶向定量 PCR 和扩增子测序进一步研究了 PCE 脱氯培养物。在转移和连续稀释过程中，已知的有机卤化物呼吸细菌（OHRB），包括 Dehalococcoides、Dehalobacter 和 Desulfitobacterium 的丰度降低，表明这些培养物中尚未表征的 OHRB 很重要。从 PCE 切换到 2,6-DBP 导致其在有硫酸盐和无硫酸盐的培养物中完全脱溴到苯酚。2,6-DBP 脱溴培养物与 PCE 脱氯培养物的微生物组成不同。最近被证实包含 OHRB 的脱硫杆菌门属，包括 Desulfovibrio 和 Desulfuromusa，在所有微宇宙中都得到了富集，而 Halodesulfovibrio 仅在没有硫酸盐的培养物中富集。在没有硫酸盐的培养物中检测到氢气和甲烷。氢气可能作为 OHR 和甲烷生成的电子供体。本研究表明，未知的 OHRB 介导的海洋环境中可能发生 OHR，这表明它们在自然卤素循环中的作用。
