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

Abstract:

[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.