碳、氮、磷源生态因子对新鞘氨醇杆菌降解微囊藻毒素的影响及分子机理

Effect of C, N, P elements on Novosphingobium sp. ERN07 degradation of microcystins

【背景】微藻囊毒素(Microcystins,MCs)是蓝藻暴发后产生的主要有害物质之一,在河口、湖泊和近海水体中均存在。【目的】研究水体营养物质浓度对新鞘氨醇杆菌(Novo sphingobium sp.ERN07)降解能力的影响,以求达到快速降解MCs的目的。【方法】通过正交实验、基因转录分析等方法鉴定菌株降解特性,了解生物降解和功能基因的表达关系,认识其降解机理。【结果】菌株去除MCs的能力受水体中碳、氮和磷源浓度的影响,由碳、氮源组成的双营养物质对生物降解抑制作用比单源弱;与标准MSM培养基相比,添加碳源、氮源和减少磷源会抑制生物降解MCs,表现为降解基因表达下调。不同营养条件下,mlr在转录水平上的基因表达不同,从而产生不同的降解效果。【结论】Novo sphingobium sp. ERN07具有较高的MCs降解能力,在水华发生之前能有效去除水环境中碳源和氮源,可以应用于治理受MCs污染的水体。

[Background] Microcystins(MCs), one of the main harmful substances produced by cyanobacterial bloom, are found in estuaries, lakes and coastal waters. [Objective] Under different concentrations of carbon, nitrogen and phosphorus sources, the paper analysed the ability of Novosphingobium sp. ERN07 to remove MCs so as to achieve rapid degradation of MCs. [Methods] The degradation characteristics were determined by orthogonal experiments and gene transcription analysis associated biodegradation with the expression of functional genes so as to understand the degradation mechanism. [Results] The dual nutrients composed of glucose and sodium nitrate had weaker inhibition of biodegradation than single glucose or sodium nitrate. Compared to those under standard MSM medium, the decelerated biodegradation with glucose or sodium nitrate(1 000 mg/L) or phosphorus source(500 mg/L) related to lower up-regulation in mlr gene expression, suggesting that divergent mlr gene expression was one of the reasons influencing various nutrient conditions on degradation. [Conclusion] Novosphingobium sp. ERN07 has a high degradation ability of MCs. Before the bloom, carbon and nitrogen sources were removed effectively so that it can be effectively used in MCs polluted water treatment.