Recent work revealed an active biological chlorine cycle in coastal Arctic tundra of northern Alaska. This raised the question of whether chlorine cycling was restricted to coastal areas or if these processes extended to inland tundra. The anaerobic process of organohalide respiration, carried out by specialized bacteria like Dehalococcoides, consumes hydrogen gas and acetate using halogenated organic compounds as terminal electron acceptors, potentially competing with methanogens that produce the greenhouse gas methane. We measured microbial community composition and soil chemistry along an ∼262-km coastal-inland transect to test for the potential of organohalide respiration across the Arctic Coastal Plain and studied the microbial community associated with Dehalococcoides to explore the ecology of this group and its potential to impact C cycling in the Arctic. Concentrations of brominated organic compounds declined sharply with distance from the coast, but the decrease in organic chlorine pools was more subtle. The relative abundances of Dehalococcoides were similar across the transect, except for being lower at the most inland site. Dehalococcoides correlated with other strictly anaerobic genera, plus some facultative ones, that had the genetic potential to provide essential resources (hydrogen, acetate, corrinoids, or organic chlorine). This community included iron reducers, sulfate reducers, syntrophic bacteria, acetogens, and methanogens, some of which might also compete with Dehalococcoides for hydrogen and acetate. Throughout the Arctic Coastal Plain, Dehalococcoides is associated with the dominant anaerobes that control fluxes of hydrogen, acetate, methane, and carbon dioxide. Depending on seasonal electron acceptor availability, organohalide-respiring bacteria could impact carbon cycling in Arctic wet tundra soils.

中文翻译：

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北极湿苔原土壤厌氧代谢中心的呼吸有机卤化物的细菌

最近的工作表明，阿拉斯加北部北极寒带苔原存在活跃的生物氯循环。这就提出了一个问题，即氯循环是否仅限于沿海地区，或者这些过程是否扩展到内陆苔原。有机卤化物呼吸的厌氧过程，是由专门的细菌（如Dehaloccocoides）进行的，使用卤代有机化合物作为末端电子受体消耗氢气和乙酸盐，有可能与产生温室气体甲烷的产甲烷菌竞争。我们测量了约262公里沿海内陆样带的微生物群落组成和土壤化学，以测试整个北极沿海平原的有机卤化物呼吸潜能，并研究了与Dehalococcoides相关的微生物群落探索这一群体的生态及其对北极碳循环的影响。溴化有机化合物的浓度随距海岸的距离而急剧下降，但有机氯池的下降更为微妙。在整个样带中，十卤代球菌的相对丰度相似，但在大多数内陆地区较低。Dehaloccocoides与其他严格厌氧属有关，加上一些兼有的属，它们具有提供必需资源（氢，乙酸盐，类海藻素或有机氯）的遗传潜力。这个社区包括铁减速，硫酸盐还原菌，细菌互养，产乙酸菌，甲烷和，其中一些还可能与竞争Dehalococcoides用于氢气和乙酸盐。在整个北极沿海平原上，Dehalococcoides与占优势的厌氧菌有关，厌氧菌控制着氢，乙酸盐，甲烷和二氧化碳的通量。根据季节性电子受体的可利用性，可吸入有机卤化物的细菌可能会影响北极湿苔原土壤中的碳循环。