基于比较转录组分析海洋弧菌X511的褐藻胶代谢途径

Analysis of the alginate metabolic pathways in the marine Vibrio X511 based on comparative transcriptome

摘要:

从北海涠洲岛海域腐烂的马尾藻中分离得到的海洋弧菌（Vibrio X511）具有较强的利用褐藻胶能力，本文利用转录组测序的方法以研究弧菌X511的褐藻胶代谢途径。[方法]采用Illumina HiSeq2500测序平台对菌株在褐藻胶及葡萄糖培养下的转录组进行测序；比较和分析差异转录本，利用荧光定量PCR验证测序结果；采用GO（Gene Ontology）和KEGG（Kyoto Encyclopedia of Genes and Genomes）对差异转录本进行功能和Pathway注释。[结果]经比较发现，菌株在褐藻胶培养下相对于葡萄糖的培养共有2024个差异表达基因，其中1066个基因上调，958个基因下调；某些普遍存在于代谢途径中的基因在不同培养条件下也存在差异表达；海洋弧菌X511中涉及褐藻胶利用的所有基因以及合成乙醇的关键基因其转录量均有一定程度的上调；此外，通过分析发现该菌株具有独特的褐藻胶利用方式，其中的一个代谢过程尚未在弧菌中被报道。[结论]成功解析了海洋弧菌X511的褐藻胶代谢途径，丰富了生物方法降解褐藻胶的研究，为大型海藻生物质能源的研究提供有价值的数据支持。

关键词:转录组;荧光定量;基因功能;褐藻胶;代谢途径

Abstract:

[Objective] A marine Vibrio X511 with strong ability to use alginate was isolated from the rotten Sargassum in the Weizhou Island of the North Sea. The metabolic pathway of using alginate by Vibrio X511 was studied by transcriptome sequencing.[Methods] Transcriptions sequencing was done by Illumina HiSeq2500 sequencing platform and the transcriptome of the strains cultured in alginate and glucose were sequenced. Differential transcripts were compared and analyzed, and the sequencing results were confirmed by fluorescence quantitative PCR. The fluorescence quantitative PCR was applied to verify the sequencing results. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes were used to annotate the function and pathway in differential transcripts.[Results] There were 2024 differentially expressed genes in the culture of alginate compared to those in glucose, with 1066 genes up-regulated and 958 genes down-regulated. Some genes in the ubiquitous metabolic pathway were also differentially expressed in different cultures. The transcriptions of all the genes involved in alginate utilization and the key genes of synthetic ethanol in Vibrio X511 were up-regulated. In addition, the strain had a unique way to utilize alginate and one of the metabolic processes has not been reported in Vibrio.[Conclusion] Our findings enrich the research of biological method for degradation of alginate, and provide valuable data for the research of large seaweed biomass-based energy.

Key words:transcriptome;fluorescence quantification;gene function;alginate;metabolic pathway