巢湖铜绿微囊藻Chao 1910的基因组学和磷代谢通路分析

Genome sequence analysis of phosphorus metabolism pathways of Microcystis aeruginosa Chao 1910 isolated from Chaohu Lake

摘要:

【背景】铜绿微囊藻(Microcystis aeruginosa)广泛分布于温带湖泊，因产生微囊藻毒素且易成为蓝藻水华优势藻株而备受关注。【目的】基于全基因组序列分析和基因转录水平验证，阐明从巢湖新分离的铜绿微囊藻Chao 1910的主要代谢通路和磷营养高效利用机制。【方法】通过第三代测序技术拼接获得Chao 1910的全基因组序列，完成主要代谢通路的基因注释，并对与蓝藻水华优势藻株形成相关的磷代谢通路进行深入分析。【结果】比较基因组学表明，Chao 1910藻株与日本铜绿微囊藻NIES-843的亲缘关系最近，其糖酵解、磷酸戊糖途径和核苷酸合成等代谢通路的基因组成非常保守，同时具有完整的磷转运、磷吸收、多聚磷酸盐合成/分解等磷营养高效利用的通路。不同于其他铜绿微囊藻，Chao 1910藻株不具有微囊藻毒素合成基因簇，推测其主要依靠对磷营养的高效利用获取生存竞争优势。【结论】Chao 1910藻株是巢湖首株完成全基因组测序的铜绿微囊藻，这将有助于揭示其获得生存竞争优势的分子机制，为遏制巢湖蓝藻水华暴发提供依据。

关键词:巢湖;铜绿微囊藻Chao 1910;全基因组分析;磷代谢通路分析

Abstract:

[Background] Microcystis aeruginosa is ubiquitous in temperate lakes and has aroused wide concern since it is a dominant bloom-forming cyanobacterium capable of producing microcystins. [Objective] To elucidate the central metabolic pathways and the efficient phosphorus-utilizing mechanism in M. aeruginosa Chao 1910 (termed Chao 1910 for short) isolated from Chaohu Lake based on the whole-genome sequence analysis and transcription verification. [Methods] The whole genome sequence was obtained by the third-generation sequencing technique, and the genes encoding the central metabolic pathways, especially the phosphorus metabolic pathways, were annotated. [Results] Chao 1910 had the closest phylogenetic relationship with M. aeruginosa NIES-843 among the Microcystis strains with known full-length genome sequences. The genes involved in the metabolic pathways such as glycolysis, pentose phosphate pathway, and nucleotide synthesis were highly conserved in Chao 1910. The genome of Chao 1910 encoded the complete pathways of phosphate transport, phosphate absorption, polyphosphate synthesis/decomposition, and other efficient phosphorus utilization pathways. Unlike other strains of M. aeruginosa, Chao 1910 did not possess the gene cluster for microcystin synthesis, which indicated that it relied on efficient phosphorus utilization to gain the competitive advantage. [Conclusion] Chao 1910 is the first M. aeruginosa strain with completed sequencing of the whole genome isolated from Chaohu Lake. It helps us to reveal the molecular mechanism of competitive advantage for the bloom-forming cyanobacteria in Chaohu Lake.

Key words:Chaohu Lake;Microcystis aeruginosa Chao 1910;whole-genome analysis;phosphorus metabolic pathway analysis