| 摘要: |
| 微囊藻藻际中生长着大量的细菌，它们影响微囊藻的生长以及藻群体的维持，在水华的生消中发挥着重要作用.在微囊藻群体的生长过程中，伴随着微囊藻群体的形成与解散，但在此过程中附生细菌群落的变化规律仍然未知.本文针对一株从太湖中分离的群体铜绿微囊藻，在不同的培养温度下监测其生长和解散过程，揭示与微囊藻群体密切相关的细菌类群.结果表明：从15 ℃到30 ℃，该群体微囊藻展示出差异化的生长周期，温度越高群体解散越快，微囊藻群体数目达到峰值的时间越短. 随着D2群体的生长，>20 μm的微囊藻群体附生细菌群落从以Pseudomonadales为主转变为以Sphingomonadales为主；3-20 μm的单细胞-小群体微囊藻附生细菌群落及游离细菌群落中的优势菌群均从Pseudomonadales转变为Cytophagales. Limnobacter只在游离细菌群落中相对丰度较高；Roseococcus只在>20 μm的D2群体附生细菌群落中有较高的相对丰度；Porphyrobacter在游离细菌群落及3-20 μm的单细胞-小群体微囊藻附生细菌群落中相对丰度较高；Mesorhizobium在3-20 μm的单细胞-小群体微囊藻附生细菌群落及> 20 μm的D2群体附生细菌群落中有较高的相对丰度.对不同粒径及不同温度下的细菌群落进行Venn图及特异性-占有率（SPEC-OCCU）图分析发现，部分独有种及特化种只在15 ℃下出现，OTU669（Methylobacteriaceae）、OTU722(Brevundimonas sp.)和OTU682(Pseudoxanthobacter sp.)在所有温度下均为>20 μm的D2群体附生细菌群落的特化种.网络分析结果表明，> 20 μm的微囊藻群体的附生细菌网络中的关键节点最多.本研究揭示了微囊藻群体生长过程中藻际细菌群落组成的变化，有助于深入了解附生细菌在微囊藻群体维持及水华中的作用. |
| 关键词: 蓝藻水华 铜绿微囊藻群体 细菌群落结构 附着细菌 游离细菌 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金项目(32371606, 31971449)联合资助。 |
|
| Changes in bacterial communities during growth and disaggregation of colonial Microcystis aeruginosa |
|
Liu Jiayin,Fang Daoyan,Zhang Yuqing,Wang Yirao,Cai Yuanfeng,Shi Limei,Li Pengfu,Wu Qinglong
|
|
State Key Laboratory of Lake Science and Environment, Key Laboratory of Lake and Watered Science for Water Security, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
|
| Abstract: |
| A large number of bacteria inhabit in Microcystis phycosphere. They affect growth and colony maintenance of Microcystis, and play important roles in the development and elimination of Microcystis blooms. Bacteria accompany the formation and disaggregation of Microcystis aeruginosa colony during their growth, but changes in bacterial communities during the process were still unclear. In this study, Microcystis colony development and bacterial community variation in a colonial Microcystis strains isolated from Lake Taihu was monitored during cultivation at different temperatures. The experimental results showed that growth pattern of this colonial Microcystis strains at different temperatures from 15 ℃ to 30 ℃ were different, the higher the temperature the faster the colonies disaggregate, the shorter the time for Microcystis aeruginosa colonies reach the peak. During the growth process of D2 colonies, the dominant bacterial communities associated with Microcystis colonies of > 20 μm shifted from Pseudomonadales to Sphingomonadales; The dominant bacterial communities associated with unicellular-small Microcystis colonies of 3-20 μm changed from Pseudomonadales to Cytophagales, which were similar to those in free-living bacterial community. On genus level, Limnobacter were dominated only in the free-living bacterial community; Roseococcus were dominated only in Microcystis colonies of >20 μm; Porphyrobacter were dominated in free living bacterial community and unicellular-small Microcystis colonies of 3-20 μm; and Mesorhizobium were dominated in unicellular-small Microcystis colonies of 3-20 μm and Microcystis colonies of > 20 μm. Venn diagrams and specificity-occupancy (SPEC-OCU) plots of bacterial communities at different particles sizes and temperatures revealed that some exclusive and specialized species only appeared at 15 ℃, OTU669 (Methylobacteriaceae), OTU722 (Brevundimonas sp.), OTU682 ( Pseudoxanthobacter sp.) were specialized species of the Microcystis colonies of > 20 μm at all temperatures. Network analyses revealed that bacterial communities in Microcystis colonies of > 20 μm had the most critical nodes. These results revealed variation pattern in bacterial community composition of different particle sizes during growth process of colonial Microcystis aeruginosa. This study would contribute to better understanding of the role of bacterial communities in Microcystis blooms. |
| Key words: Cyanobacterial bloom Microcystis aeruginosa colony bacterial community attached bacteria free-living bacteria |
