光合细菌强化富营养化水体土著细菌抑藻作用的研究

Cyanobacteria blooms are a worldwide problem that brings a serious threat to people’s life and production. It is urgent to control bloom through effective methods. Photosynthetic bacteria (PSB) have attracted much attention because of their excellent ability to inhibit the growth of cyanobacteria. However, there are few studies on the algal growth inhibition mechanism of PSB. In the current research on the algal inhibition by PSB alone, the concentration of PSB must be above 10^5 CFU/mL to inhibit growth of the cyanobacteria. However, PSB with a concentration of 10^3 CFU/mL can have a significant algal inhibition activite when applied in actual water bodies. In order to explain this contradiction, we proposed a new scientific hypothesis based on the existence of algicidal bacteria in actual eutrophic water bodies: PSB can inhibit the growth of the cyanobacteria by enhance the algal inhibition activite of some bacteria in eutrophic water bodies. This project intends to further explore the universality of this phenomenon and to reveal the underlying mechanism by analyze the interaction between PSB and algicidal bacteria and identify the signal molecules of PSB. The phenomena and mechanism discovered in this project will provide methods and theoretical guidance for the control of cyanobacteria blooms.

蓝藻水华在世界范围内频发，对人们的生产生活造成了很大的危害，亟需找到有效途径控制蓝藻水华。光合细菌由于其优异的抑藻能力而受到了人们的关注，但是关于其抑藻机制的研究却不多。根据报道，单独作用时光合细菌在较高的浓度（10^5 CFU/mL）时才具有抑藻效果，而在实际应用时，光合细菌在很低的浓度（10^3 CFU/mL）就可以有显著的抑藻效果。为了解释这一矛盾的现象，申请人基于实际富营养水体本身存在抑藻细菌的分析结果，提出新的科学假说：光合细菌能够作用于富营养化水体中的某些抑藻细菌，强化其抑藻作用，最终达到控制蓝藻数量的目的。本项目拟通过光合细菌强化富营养化水体土著细菌抑藻作用的普遍性研究、光合细菌与抑藻细菌相互作用关系的研究、结合光合细菌强化抑藻物质的分离鉴定，揭示其内在作用机制。本项目发现的现象及阐明的机理将为蓝藻水华的防治提供方法和理论上的参考。

光合细菌由于其优异的抑藻能力而受到了人们的关注，但是其抑藻机制仍不明晰。本项目首先验证了光合细菌强化富营养化水体土著细菌抑藻作用的普遍性；此后经过抑藻细菌的筛选及其与光合细菌R. faecalis JS的联合抑藻实验，发现光合细菌能够通过分泌胞外活性物质的方式，强化抑藻细菌的抑藻作用；对联合抑藻过程中抑藻细菌P. protegens AB-13的转录组学研究，发现添加光合细菌发酵液后细菌P. protegens AB-13中与群体感应、双组分系统、全局转录调控因子、以及毒力合成分泌等相关基因均发生显著上调，说明光合细菌可以刺激细菌抑藻物质的合成与分泌；之后根据理化性质对光合细菌促进细菌抑藻的活性物质进行分离，经乙醇抽提、1KD透析袋透析、高效液相色谱分离后，得到22种可能的代谢物，最后验证发现代谢物中可能的强化抑藻细菌抑藻作用物质为N-己酰基-DL-高丝氨酸内脂和N-丁酰基-DL-高丝氨酸内脂。本项目的研究结果说明光合细菌可能通过释放高丝氨酸内脂类信号分子来调控细菌的群体感应系统，从而提升细菌的抑藻能力，抑制水华蓝藻的生长。本项目阐明的机理将为蓝藻水华的生物防治提供方法指导及理论依据。

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