古丸菌Archaeoglobi的代谢特征

古丸菌纲(Archaeoglobi)是广古菌门下的纲级分类单元,包含古丸菌(Archaeoglobus)、地丸菌(Geoglobus)和铁丸菌(Ferroglobus)三个属,所属菌株均是严格嗜热厌氧菌,主要分布于海洋、陆地热液系统和油田环境中。Archaeoglobus属下的微生物是一类以硫酸盐、亚硫酸盐或硫代硫酸盐为电子受体代谢生成硫化氢(H2S)的化能自养或氢营养型微生物;而Geoglobus和Ferroglobus的成员则主要还原硝酸盐和铁离子。Archaeoglobi地理分布广泛,在元素生物地球化学循环过程中发挥着重要作用,是目前微生物生态学研究的一个热点。在进化方面,Archaeoglobi菌和产甲烷古菌具有较高的亲缘关系;同时,Archaeoglobi基因组中保留着部分产甲烷途径上的功能基因,最新研究表明部分未培养的Archaeoglobi基因组中含有完整的产甲烷通路。这些证据都表明Archaeoglobi菌的基因组特征可能是产甲烷古菌向硫酸盐还原菌进化的活化石。本文梳理了目前发现的11株Archaeoglobi菌株的生理生化特征和基因组分析结果,从化能自养、化能异养、硫化物呼吸、产乙酸、产甲烷等方面综述了已分离的Archaeoglobi菌的代谢特征,并基于宏基因组信息分析了未培养的Archaeoglobi菌基因组中的潜在代谢功能,为进一步分离培养此类未培养厌氧微生物提供理论指导。

Metabolic characteristics of Archaeoglobi

Archaeoglobi is a class of thermophilic Archaea belonging to the Euryarchaeota, covering three genera:Archaeoglobus, Geoglobus and Ferroglobus. Archaeoglobus are all heterotrophic or chemolithotrophic sulfate reducers using sulfate, sulfite or thiosulfate as electron acceptors, with the formation of hydrogen sulfide as the end product. Geoglobus and Ferroglobus may reduce both nitrate and ferric irons. Archaeoglobi are strictly thermophilic anaerobes, which are widely distributed the natural environments and are dominant in some environments, such as oceans, terrestrial hydrothermal systems and terrain environments. Due to wide geographic distribution and diverse metabolic potential, and activity perform in metabolism of various elements, Archaeoglobi may play an important role in the global element cycle and has become a scenic spot for microbial ecology research. Members of Archaeoglobi phylogenetically close to methanogenic Euryarchaeota in their evolutionary history; on the other hand, fuctional genes of archaeal type Wood-Ljungdahl (WL) pathway are present in partial Archaeoglobi genomes, even the newest studies suggest that uncultured Archaeoglobi genomes contain complete mathanogensis pathway, these evidences provides new insights into the evolutionary transition from methanogenic archaea to sulfate-reducing bacterial. This review collected the information of the physiological, biochemical characteristics and genome analysis of eleven reported Archaeoglobi strains, summarized the metabolic characteristics of those isolated Archaeoglobi in terms of the aspects of chemolithoautotrophic, chemotherapeutic, sulfite reduction, acetogenesis, methanogenesis, and analyzed the potential metabolic functions of uncultured Archaeoglobi genomes based on the metagenomic information, which may provide theoretical guidance for the further isolation and cultivation of this kind of uncultured anaerobic microorganisms.