聚球藻共栖细菌群落结构与功能特征

Community composition and functional characteristics of symbiotic bacteria of Synechococcus

聚球藻与共栖细菌能够通过功能互补实现互惠共生。本研究通过分析原位聚球藻富集培养体系除菌处理前后的藻菌体系的群落结构及生理指标差异,探究了稳定共栖优势菌群的功能特征及其生态影响。结果表明:培养体系聚球藻以S5.1_Ⅷ类群为主,优势共栖细菌属于α-变形菌、γ-变形菌和拟杆菌;除菌后重建的稳定共栖细菌群落结构趋于一致,优势种群是Ruegeria和Marianobacter,功能解析发现碳和氮循环功能类群相对丰度分别为88.47%和11.08%。受共栖菌群影响的聚球藻藻胆蛋白含量和最大光合能力发生显著变化,光能转化效率提高。此外,聚球藻培养过程中释放了大量硅,可能为微微型浮游植物的聚集下沉提供压载物,促进海洋碳循环。

Synechococcus and its phycosphere bacteria can achieve mutualism through functional complementarity.In this study,the functional characteristics and ecological effects of stable symbiotic dominant bacteria were investigated by analyzing the differences of community structure and physiological indices of the algal-bacteria system before and after bacteria removal of in situ Synechococcus enrichment culture system.The results showed that Synechococcus mainly belonged to S5.1_Ⅷ subgroup,and that the dominant classes of symbiotic bacteria were α-Proteobacteria,γ-Proteobacteria,and Bacteroides.After bacteria removal,community structure of recombinant stable symbiotic bacteria tended to be consistent,with Ruegeria and Marianobacter as the dominant populations.The results of function annotation showed that the relative abundance of bacterial groups involved in carbon and nitrogen cycling was 88.47% and 11.08%,respectively.Affected by symbiotic dominant bacterial community,phycobiliprotein contents and maximum photosynthetic capacity of Synechococcus significantly changed,and light conversion efficiency increased.Furthermore,Synechococcus released large amounts of silicon during cultivation,which may provide ballasting mineral for the aggregation and sinking of pico-phytoplankton and promote marine carbon cycling.