不产氧光合细菌对微囊藻生长及其产毒的影响及作用机理

As the Microcystis bloom and its release toxins have severely affected on the safety of aquatic ecosystems and human's health, to realize the occurrence and disappearance of Microcystis bloom and its toxin-producing mechanism is always a hot research topic in recent years. However, most studies were mainly focus on a single non-biological factor's effect on the growth and microcystin production of Microcystis strains, little attention is given to the biological factors, such as some specific microbials' effects. Hence, in order to investigate the role of anoxygenic phototrophic bacteria (APA) on the growth and microcystin production of different Microcystis strains, we select the widespread anoxygenic phototrophic bacteria in the freshwater lakes and the common algae bloom dominant species-Microcystis, and carry out the microcosm laboratory experiments and in situ investigation. The objectives of the study are (1) to elucidate the influence of the photosynthetic bacteria on the growth and toxin production capacity of different Microcystis strains under different environmental conditions, (2) to clarify mechanism of anoxygenic phototrophic bacteria on the growth of Microcystis and its toxin-production process, (3) to answer scientific problem "how photosynthetic bacteria influence the growth of Microcystis and its toxin production capacity ", (4) to obtain a more comprehensive understanding and accurate assessment of the occurrence and disappearance of Microcystis bloom and its toxin-production mechanism in aquatic ecosystem, and (5) to reveal the role of photosynthetic bacteria of regulatory the freshwater algae in the lake eutrophication process, and provide helpful information for the method of eutrophication control.

鉴于微囊藻水华及其释放毒素对水生生态系统和人类健康安全的严重危害性，认识微囊藻水华的暴发和消亡规律及其毒素的产生机制一直是国内外研究的热点。而目前大部分研究主要聚焦在单一非生物因子（光照、温度、营养元素等）对其生理过程和产毒能力的影响，而忽视了不同环境条件下某些特异性微生物作用的影响。因此，本研究拟选取淡水水体中广泛存在的不产氧光合细菌和常见的水华优势藻类微囊藻为研究对象，采用野外围隔原位试验与室内模拟控制相结合的研究方法，探讨不同环境条件下光合细菌对不同微囊藻的生长状况及其产毒能力的影响，阐明不产氧光合细菌在微囊藻细胞生长及产毒过程中的作用机理，解答"光合细菌是如何影响微囊藻细胞生长及其产毒能力"这一科学问题，为更全面了解和准确评估水生态系统中的微囊藻水华的暴发和消亡规律及其毒素的产生机制，并揭示光合细菌在湖泊富营养化过程中对淡水藻类的调控作用以及为富营养湖泊的治理提供科学依据。

蓝藻水华频繁暴发是影响全球公众健康和环境保护的重大环境问题。大规模的蓝藻水华降低了水资源利用效能，引起严重的生态破坏及巨大的经济损失。其中微囊藻是形成蓝藻水华的主要优势种之一。对水华微囊藻的有效去除和处置是解决蓝藻水华问题的关键。本项目针对不产氧光合细菌强大分解能力和灵活多样的代谢模式，重点研究了光合细菌在蓝藻（微囊藻）消亡和处理处置中的应用潜力。首先开展了富营养化湖泊沉积物中不产氧光合细菌（APB）优势种的分离纯化及其在不同水环境条件下的生理生态响应”的研究。从东湖水体中成功分离了一株紫色非硫沼泽红假单胞菌PUF1 （Rhodopseudomonas palustris strain PUF1），确定PUF1的较佳培养条件。此外，野外调查结果显示，自然水体中好氧不产氧光合细菌亦普遍存在，并与藻生物量有一定的依存关系。通过室内模拟实验探讨了紫色非硫沼泽红假单胞菌与微囊藻的相互作用规律，研究发现添加APB对微囊藻生长具有一定的抑制作用。根据研究结果，PUF1可耐受较高浓度的氨氮，决定了其可应用于蓝藻的厌氧消化，在此基础上优化构建了光合细菌-蓝藻的培养体系；另外，应用半连续补料系统，光合细菌产量较稳定，培养周期短，可大大减少废水的排放。研究结果为蓝藻的资源化提供了新方向，应用光合细菌可有效减少由蓝藻腐败引起的营养流失及臭味污染等环境污染问题，有助于进一步控制蓝藻水华的规模和强度。本研究中尚未成功分离到好氧不产氧光合细菌且鲜有分离成功案例报道。有关好氧不产氧光合细菌（AAPB）与微囊藻的相互作用，建议以本项目为研究基础，进一步优化分离底物，深入分析AAPB与微囊藻消长的环境行为关系。整个基金执行期间，整理并发表了具有本基金署名的10篇科研论文，受理了发明专利1项，实用新型1项。