ABSTRACT

Microbial degradation of organic matter along the vertical profile of the water column is a major process driving the carbon cycle in the ocean. Pseudoalteromonas has been identified as a dominant genus in pelagic marine environments worldwide, playing important roles in the remineralization of organic carbon. However, the current understanding of Pseudoalteromonas was mainly based on shallow water populations or cultivated species. This study analyzed for the first time the structure, activity potential and ecotypes differentiation of Pseudoalteromonas in the water column of the New Britain Trench (NBT) down to 6000 m. Analysis on diversities of the 16S rRNA gene and their transcripts showed that Pseudoalteromonas was greatly enriched in deep-sea waters and showed high activity potentials. The deep-sea Pseudoalteromonas were significantly different from their shallow-water counterparts, suggesting an obvious ecotype division along with the vertical profile. Phylogenetic analysis on the 16S rRNA gene and hsp60 gene of 219 Pseudoalteromonas strains isolated from different depths further showed that the vertical ecotype division could even occur at the strain level, which might be a result of long-term adaptation to environmental conditions at different depths. The discovered depth-specific strains provide valuable models for further studies on adaptation, evolution and functions of the deep-sea Pseudoalteromonas.

中文翻译：

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新不列颠海沟垂直水柱假交替单胞菌种群结构、活动潜力及生态型划分

摘要

沿水体垂直剖面的有机物微生物降解是推动海洋碳循环的主要过程。假交替单胞菌已被确定为全球远洋海洋环境中的优势属，在有机碳的再矿化中发挥着重要作用。然而，目前对假交替单胞菌的认识主要基于浅水种群或栽培种。本研究首次分析了新不列颠海沟（NBT）6000米以下水体中假交替单胞菌的结构、活动潜力和生态型分化。对 16S rRNA 基因及其转录本多样性的分析表明，假交替单胞菌在深海水域中大量富集并显示出很高的活动潜力。深海假交替单胞菌与其浅水对应物显着不同，表明沿垂直剖面存在明显的生态型划分。对不同深度分离的219株假交替单胞菌菌株16S rRNA基因和hsp60基因的系统发育分析进一步表明，垂直生态型划分甚至可能发生在菌株水平，这可能是长期适应不同深度环境条件的结果。发现的深度特异性菌株为进一步研究深海假交替单胞菌的适应、进化和功能提供了有价值的模型。