马里亚纳海沟沉积物可培养异养细菌的多样性及其DMSP降解能力

Diversity of culturable heterotrophic bacteria from sediments of the Mariana Trench and their ability to degrade dimethylsulfoniopropionate (DMSP)

摘要:

[目的] 马里亚纳海沟是地球上最深的海沟，具有超高静水压力、低温、无光等生境特征，蕴含独特的微生物资源。二甲基巯基丙酸内盐（dimethylsulphoniopropionate，DMSP）是海洋环境中最丰富的有机硫分子之一，海洋异养微生物可裂解DMSP产生“冷室气体”二甲基硫（dimethyl sulfide，DMS），在全球硫循环和气候变化中发挥着重要作用。本研究对马里亚纳海沟沉积物异养细菌进行分离鉴定，并研究其DMSP降解能力，为阐明深渊微生物的生命过程提供独特的微生物资源。[方法] 本文以马里亚纳海沟5个站位的沉积物为研究对象，利用3种常规异养菌培养基（2216E、R2A和TCBS）及2种异养菌富集培养基（TCBS肉汤和碱性蛋白胨水）在4℃、16℃和28℃下进行细菌分离培养，通过16S rRNA基因测序鉴定其分类地位，并对代表菌株进行DMSP降解能力检测。[结果] 共分离鉴定异养细菌1057株，分属于4个门、7个纲和76个属。γ-变形菌纲（Gammaproteobacteria）为优势菌群，占据可培养异养细菌总数的61.4%，假单胞菌属（Pseudomonas）和盐单胞菌属（Halomonas）为主要的优势属；变形菌门（Proteobacteria）相对丰度在沉积物各层样品中均占绝对优势。厚壁菌门（Firmicutes）相对丰度深层高于表层。碱性蛋白胨水和TCBS肉汤培养基分别对放线菌纲（Actinobacteria）和芽孢杆菌纲（Bacilli）具有更好的选择性；101株细菌与其最相似物种的16S rRNA基因相似度小于98.65%，为潜在新分类单元。本文进一步选取134株异养细菌进行DMSP降解能力测定，发现52株（38.8%）具DMSP裂解活性。[结论] 马里亚纳海沟沉积物中可培养细菌及DMSP降解菌株均具有较高的多样性，我们的研究为进一步开展深渊微生物生命过程研究提供了宝贵的微生物资源。

Abstract:

[Objective] The Mariana Trench is the deepest trench on earth. It has the characteristics of ultra-high hydrostatic pressure, low temperature and lack of light and contains unique microbial resources. Dimethylsulfoniopropionate (DMSP) is one of the marine's most abundant organosulfur molecules. Marine heterotrophic microorganisms can cleave DMSP and release “cooling gas” dimethyl sulfide (DMS), which plays an important role in driving global sulfur cycling and regulating global climate change. The heterotrophic bacteria from sediments of the Mariana Trench were isolated and identified and their ability to degrade DMSP was studied. Our study provides unique microbial resources for elucidating the life process of abyssal microorganisms. [Methods] Our study collected the sediments from five stations of the Mariana Trench as subject, using three kinds of conventional heterotrophic bacteria culture media (2216E, R2A and TCBS) and two kinds of heterotrophic bacteria enrichment culture media (TCBS broth and alkaline peptone water) for isolation and cultivation of bacteria at 4 ℃, 16 ℃ and 28 ℃, respectively. [Results] A total of 1057 strains were isolated and identified. And these isolates belonged to four phyla, seven classes and 76 genera. Gammaproteobacteria was the most abundant class, accounting for 61.4% of the total isolates. Pseudomonas and Halomonas were the most abundant genera; Proteobacteria was dominated in samples of all layers of sediments. The relative abundance of deep layer of Firmicutes was higher than that of the surface layer; The alkaline peptone water (AP) medium were found to have a better selectivity to Actinobacteria, and the TCBS broth medium were found to have a better selectivity to Bacilli; 101 strains were potential novel taxa of bacteria; In this study, the ability to degrade DMSP of 134 representative heterotrophic bacteria were tested, and 52 strains were found to have the ability to cleave DMSP and release DMS, accounting for 38.8% of the tested strains. [Conclusion] These results indicate that there is a high diversity of culturable bacteria and strains that have the ability to degrade DMSP from sediments of the Mariana Trench. Our research provides valuable microbial resources for further research on the life process of abyssal microorganisms.