红树林沉积物中天然多聚有机物厌氧降解菌多样性与细菌新类群分离

目的]红树林沉积物中有机物丰富,通过研究认识参与难降解天然有机多聚物的微生物降解过程及其环境作用,并获得新颖的难培养厌氧微生物。方法]对漳州九龙江河口红树林沉积物中降解纤维素、几丁质和木质素的厌氧细菌定向富集和平板分离纯化,并对其多样性进行分析。结果]共筛选分离获得202株厌氧细菌(82株专性厌氧细菌,120株兼性厌氧细菌),包括4个疑似新属(Lachnotalea sp.MCCC 1A16036、Varunaivibrio sp.MCCC 1A15903、Clostridium sp.MCCC 1A15884、Caminicella sp.MCCC 1A17445)和4个疑似新种(Sunxiuqinia sp.MCCC 1A15904、Pseudodesulfovibrio sp.MCCC 1A16040、Pseudodesulfovibrio sp.MCCC 1A16038、Mangrovibacterium lignilyticum MCCC1A15882)。不同天然有机多聚物富集菌群分离到的优势可培养细菌主要属于变形菌门、拟杆菌门和厚壁菌门,但种群略有差异。在纤维素和几丁质富集菌群中,变形菌门和拟杆菌门菌株是纤维素和几丁质富集菌群的优势菌群,拟杆菌门的Prolixiacer bellariivorans、Mangrovibacterium lignilyticum和变形菌门的Desulfovibrio salexigenes、Vibrio alginolyticus分别在纤维素和几丁质富集菌群可培养细菌中占绝对优势。但降解实验表明,放线菌门细菌Demequina salsinemoris MCCC 1A15890和Brevibacterium celere MCCC 1A17451对纤维素降解活性最高。梭杆菌门细菌Propionigenium maris MCCC 1A15874和Ilyobacter polytropus MCCC 1A15889对几丁质降解活性最高。在木质素富集菌群中,拟杆菌门的Mangrovibacterium lignilyticum和厚壁菌门的Clostridium amygdalinum都具有较高的相对丰度。变形菌门细菌Desulfomicrobium apsheronum MCCC 1A15932和拟杆菌门细菌Mangrovibacterium lignilyticum MCCC 1A15882对木质素降解效果显著。结论]红树林沉积物中存在丰富多样且新颖的厌氧难培养细菌,且多数具有纤维素、几丁质或木质素厌氧降解能力。该研究结果为探究红树林沉积物原位环境天然有机多聚物碳的生物地球化学循环机制提供了相关理论基础和纯培养微生物资源。

Diversity of anaerobic degrading bacteria for natural organic polymers in mangrove sediments and isolation of novel groups of bacteria

Objective] Organic matters are rich in the mangrove sediments. This research was aimed to understand the community structure and degradation process of microorganisms involved in natural organic polymers and their environmental roles. Methods] Using anaerobic microbial culture technology to enrich, isolate and analyze the microbial diversity of anaerobic bacteria that involved in degrading cellulose, chitin and lignin in the mangrove sediments of the Jiulong River Estuary in Zhangzhou. Results] A total of 202 anaerobes (82 obligate anaerobes and 120 facultative anaerobes) were isolated. Among those strains, four candidate novel genera (named Lachnotalea sp. MCCC 1A16036, Varunaivibrio sp. MCCC 1A15903, Clostridium sp. MCCC 1A15884 and Caminicella sp. MCCC 1A17445, respectively) and four candidate novel species (named Sunxiuqinia sp. MCCC 1A15904, Pseudodesulfovibrio sp. MCCC 1A16040, Pseudodesulfovibrio sp. MCCC 1A16038 and Mangrovibacterium lignilyticum MCCC 1A15882, respectively) were isolated. The dominant cultivable bacteria isolated from different substrate enrichments mainly belong to phyla Proteobacteria, Bacteroides and Firmicutes, but the population is slightly different. The species Prolixibacter bellariivorans and Mangrovibacterium lignilyticum, which belong to the phylum Bacteroides, and the species Desulfovibrio salexigenes and Vibrio alginolyticus, which belong to the phylum Proteobacteria, are most dominant in cellulose and chitin-enriched microbial communities. The strains Demequina salsinemoris MCCC 1A15890 and Brevibacterium celere MCCC 1A17451 (in the phylum Actinobacteria) showed the highest degradation activity to cellulose, while the strains Propionigenium maris MCCC 1A15874 and Ilyobacter polytropus MCCC 1A15889 (in the phylum Fusobacteria) showed the highest degradation activity to chitin. Among the lignin enriched bacteria, Mangrovebacterium lignlyticum (in the phylum Bacteroides) and Clostridium amygdalinum (in the phylum Firmicutes) had high relative abundance. The strains Desulfomicrobium apsheronum MCCC 1A15932 (in the phylum Proteobacteria) and Mangrovibacterium lignilyticum MCCC 1A15882 (in the phylum Bacteroides) have significant efficiency on lignin degradation. Conclusion] There are diverse, novel and difficult-to-cultivable anaerobic bacteria in mangrove sediments, and most of them have the ability to degrade cellulose, chitin or lignin in anaerobic condition. The results will provide relevant theoretical basis and bacterial resources to explore the biogeochemical cycle of organic polymer carbon in environment of mangrove sediments in situ.