分层型水库藻类季相演替的细菌种群驱动机制

浮游藻类和水体中的细菌是水生食物网的组成部分，在淡水生态系统的结构和功能中发挥着关键作用.然而，对于水库当中藻类和细菌群落如何互作及其对变化的环境条件的响应研究却较少.本文以李家河水库为研究对象，采用16S rDNA高通量测序技术和共生网络分析方法，分析了藻类种群时空演替与细菌群落的生态互作关系.结果表明，在藻类群落结构中，硅藻和绿藻也为全年优势门类，且在8月，蓝藻取代硅藻成为第二大优势门类，平均相对丰度为30.13%.DNA测序分析表明，变形菌门、放线菌门和拟杆菌门为全年优势细菌，其中变形菌门在7月达到全年最大相对丰度71.68%.酸杆菌门和异常球菌-栖热菌门作为稀有类群，其相对丰度最大分别为10.20%和5.56%.共生网络分析表明，藻类与细菌之间的关系以正相关居多，表明二者之间的互作关系可能以互利共生为主.Methylotenera作为关键节点，与小球藻呈显著正相关.柵藻作为藻类群落中的关键节点，与甲基杆菌属、Solitalea和红育菌属等多种细菌显著负相关.RDA分析表明，藻类和细菌群落的演替受到水温、pH和电导率的显著调控，环境因子对藻类和细菌群落变异解释分别为93.1%和90%.本研究结果将为深水型水源水库生态系统中藻菌互作关系的微生态驱动机制提供科学依据.

Mechanism of Algal Community Dynamics Driven by the Seasonal Water Bacterial Community in a Stratified Drinking Water Reservoir

Phytoplankton and bacteria are crucial components of aquatic food webs, playing critical roles in the structure and function of freshwater ecosystems. However, there are few studies on how the algal and bacterial communities interact and respond to changing environmental conditions in the water reservoirs. Thus, the ecological interaction relationship between the temporal succession of the phytoplankton community and the bacterial community was investigated using 16S rDNA high-throughput sequencing and a co-occurrence network in the Lijiahe Reservoir. The results showed that Bacillariophyta and Chlorophyta were also dominant taxa in the phytoplankton community. In August, Cyanobacteria replaced Bacillariophyta as the second-most dominant taxa, with an average relative abundance of 30.13%. DNA sequencing showed that Proteobacteria, Actinobacteria, and Bacteroidetes dominated throughout the year. Proteobacteria reached a maximum relative abundance of 71.68% in July. Acidobacteria and Deinococcus-Thermus, which were rare taxa, reached maximum relative abundances of 10.20% and 5.56%, respectively. The co-occurrence network showed that the association between algae and bacteria was mainly positive, indicating that the interaction between them may be dominated by mutualism. As a keystone taxa, Methylotenera was significantly and positively related to Chlorella. Scenedesmus was also a keystone taxa and was significantly and negatively correlated with various bacteria, such as Methylobacter, Solitalea, and Rhodoferax. An RDA analysis showed that the succession of algal and bacterial communities was significantly regulated by water temperature, pH, and conductivity, and the environmental factors explained 93.1% and 90% of the variation in the algal community and bacterial community, respectively. The results will provide a scientific basis for exploring the micro-ecological driving mechanism of the interaction between algae and bacteria in deep drinking water reservoir ecosystems.