环境水体中蓝藻mcy基因变异特征及基因丰度对微囊藻毒素的影响

Microcystins (MCs) produced by harmful cyanobacterial blooms pose a serious threat to human and animal health; thus, the early warning, prevention, and control of the potential hazards of MCs is one of the environmental problems to be solved. Since the mcy genes that control the biosynthesis of MCs in cyanobacteria are prone to loss and mutation, toxic and non-toxic cyanobacterial subpopulations commonly coexist in environmental waters. Effectively distinguishing these toxic and non-toxic cyanobacteria is of great significance to revealing the associations between mcy gene abundance and MC concentration, analyzing the potential pollution intensity caused by cyanobacterial blooms, and reducing the environmental risk of MCs. Currently, the contribution of mcy gene mutation to the non-toxic cyanobacterial subpopulation remains to be further studied. In this project, Microcystis, Planktothrix, and Anabaena (three typical toxic genera of cyanobacteria) are selected for systematic analysis of mcy gene mutation by using culture-dependent and -independent methods. Further, quantitative assessments of the mcy genes and their mutations in environmental waters are performed by qPCR. Building on this, a methodological system for estimation of “toxigenic mcy genes” is established, and a model of the dose-response relationship between “toxigenic mcy genes” abundance and MC concentration for ecological risk assessment is constructed. The aim of this work is to clarify the effects of abundance changes in the toxic and non-toxic cyanobacterial subpopulations on MC concentration and the underpinning mechanisms in the environment. The results will provide useful reference and technical support for the early warning, prevention, and control of the potential detrimental health effects of MCs.

有害蓝藻水华产生的微囊藻毒素（MCs）对健康造成严重威胁，对其潜在危害预警防控是亟需解决的环境问题。控制MCs合成的微囊藻毒素基因（mcy）易发生丢失和变异，由此导致具有产毒或无毒特征的蓝藻亚种群在环境中普遍共存。有效区分蓝藻的有毒与无毒亚种群，对阐明mcy基因丰度与MCs含量的关系，解析蓝藻水华潜在污染强度，降低MCs的环境风险具有重要意义。目前，mcy基因变异对无毒亚种群的贡献尚有待深入研究。本项目拟以微囊藻、浮丝藻和鱼腥藻为研究对象，结合常规纯培养与免培养的研究方法，对mcy基因变异特征进行系统分析；通过对环境水体中mcy基因及其变异的定量研究，建立估算环境中“mcy有效产毒基因”的方法体系，构建用于生态风险评估的“mcy有效产毒基因”丰度变化与MCs产量间的剂量-效应关系模型。以期阐明环境中有毒与无毒亚种群丰度变化对MCs产量变化的影响及机制，为预警防控MCs潜在环境危害提供基础。

有害蓝藻水华产生的微囊藻毒素（MCs）对健康造成严重威胁，对其潜在危害预警防控是亟需解决的环境问题。然而，具有产毒或无毒特征的蓝藻亚种群在环境中普遍共存。有效区分蓝藻的有毒与无毒亚种群，对阐明mcy基因丰度与MCs含量的关系，解析蓝藻水华潜在污染强度，降低MCs的环境风险具有重要意义。目前，mcy基因变异对无毒亚种群的贡献尚有待深入研究。.本项目通过二代和三代宏基因组技术的结合，研究了环境水体中浮游生物的群落结构和功能特征；通过对mcy基因变异特征进行系统分析，研究了mcy基因中snp的变异特征；通过室内培养的方法，研究了聚苯乙烯微塑料（PS）对铜绿微囊藻生长和产毒的影响。.1）采集了太湖的蓝藻水华样本，分析了太湖蓝藻水华浮游生物及微囊藻的群落结构，对水体环境中浮游生物的功能基因多样性进行了分析。环境中mcy基因簇中含有大量的SNP基因和少量基因缺失，未发现大片段的基因插入。本研究通过实验和前人的研究结果，总结了位于mcy基因前后及内部的常见转座子ISPlr1在mcy基因内插入和逃逸的规律。.2）采集了滇池和抚仙湖不同地点的样品，以及咸阳湖自2019年至2021年间非连续的时间样本；对DNA样品进行分离提取及保藏，以备对其变异基因的定量研究。此外，对湖泊样本的滤液进行了过滤和保藏，以备后续采用高效液相色谱法(HPLC)法测定各湖泊样本中主要的3种MC的含量。为初步建立环境中“mcy有效产毒基因”丰度变化与MCs总量之间的剂量-效应关系模型提供初步数据基础。.3）以环境中大量存在聚苯乙烯微塑料（PS）为材料对铜绿微囊藻进行胁迫试验研究，以铜绿微囊藻为研究对象，研究了聚苯乙烯微塑料（PS）对微囊藻毒素生长和产毒的影响。研究发现，纳米PS对于铜绿微囊藻的生长抑制率均在暴露的96 h后达到最大值，而后逐渐下降，并在指数生长中后期（第8天）趋于平缓；而高浓度的纳米PS在短期暴露时会对铜绿微囊藻细胞的生长造成明显的抑制作用；低浓度（1 mg·L-1）纳米PS在暴露出其体现出短暂的促进生长作用。.