脱卤单胞菌属在厌氧降解有机氯化物及污染场地修复应用中的研究进展

Advances of using Dehalogenimonas in anaerobic degradation of chlorinated compounds and bioremediation of contaminated sites

摘要:

脱卤单胞菌Dehalogenimonas是绿弯菌门 (Chloroflexi) 脱卤球菌纲 (Dehalococcoidia) 的一个属。脱卤单胞菌属目前包含Dehalogenimonas lykanthroporepellens、Dehalogenimonas alkenigignens和Dehalogenimonas formicexedens这3个已正式命名的物种，其成员均为严格厌氧的专性有机卤呼吸细菌，利用氢气和甲酸作为电子供体，以氯代烷烃 (例如1,2,3-三氯丙烷、1,2-二氯丙烷和1,2-二氯乙烷) 作为电子受体，通过介导还原性脱氯反应获得能量进行生长。我国污染场地地下水中氯代烷烃等有机氯污染较为突出，脱卤单胞菌的产能方式使其在污染场地原位修复中具有重要的应用价值。新近发现的WBC-2菌株和“Candidatus Dehalogenimonas etheniformans” GP菌株可以脱氯降解某些氯代烯烃，其中GP菌株能够将一氯乙烯完全脱氯至乙烯，拓展了有限的一氯乙烯脱氯菌种资源，丰富了脱卤单胞菌的生态学功能。文中围绕脱卤单胞菌属的生理生化特性、生态功能及基因组信息进行综述，旨在为污染场地有机氯污染物的清理及工程实施提供理论指导。

Abstract:

The genus Dehalogenimonas (Dhgm) is a recently discovered taxonomic group within the class Dehalococcoidia of the phylum Chloroflexi. To date, Dhgm consists of three formally described species including Dehalogenimonas lykanthroporepellens, Dehalogenimonas alkenigignens and Dehalogenimonas formicexedens. All isolates of these three Dhgm species are obligate organohalide-respiring bacteria. They use hydrogen and formate as electron donors and chlorinated ethanes (e.g., 1,2,3-trichloropropane, 1,2-dichloropropane, 1,2-dichloroethane) as electron acceptors in energy-conserving reductive dechlorination reaction. Chlorinated ethanes are common groundwater contaminants in China. The unique metabolic capacities of Dhgm strains implicate it may play important roles in site remediation. The recently reported Dhgm sp. strain WBC-2 and ‘Candidatus Dehalogenimonas etheniformans’ strain GP are capable of dechlorinating certain chlorinated ethenes. More importantly, strain GP can completely detoxify the carcinogenic vinyl chloride (VC) to ethene. These findings expand the diversity of microorganisms involved in the respiratory VC reductive dechlorination and improve the understanding of Dhgm’s ecological functions. Here, we summarize the advances in physiological and biochemical characteristics, ecological functions and genomic features of Dhgm, with the aim to develop effective and sustainable strategies to facilitate the bioremediation of chlorinated compounds contaminated sites.