达里湖表层水体浮游细菌群落结构的夏-冬季节差异

为探索寒旱区湖泊在夏季非冰封开放、冬季冰冻近封闭等状态差异下表水中典型理化指标和浮游细菌群落结构差异,利用2018年7月和2019年1月采集的内蒙古达里湖41个表水(冰)样品,基于16S rRNA高通量测序和典型理化指标含量分析,讨论了浮游细菌群落结构特征及其对氮(N)和磷(P)元素等理化指标的夏-冬季节差异的响应.首...

Characteristics of Planktonic Bacteria Community Between Summer and Winter Surface Water in Dali Lake

Lakes are usually influenced by the obvious seasonal changes that occur in cold and arid areas, in which they are nearly completely covered by ice during the winter but receive large amounts of precipitation and other exogenous inputs during the summer. In this study, we collected a total of 41 surface water and ice samples in July, 2018, and January, 2019, in Dali Lake, an inland closed lake located in the Inner Mongolia Plateau. Through 16S rRNA gene-based high throughput sequencing technology, coupled with comparisons of physicochemical proxies between summer and winter surface water samples, the seasonal characteristics of the planktonic bacterial community were analyzed in detail. First, the contents of total nitrogen (TN), total phosphorus (TP), dissolved inorganic phosphorus (DIP), dissolved total phosphorus (DTP), electrical conductivity (EC), and oxidation-reduction potential (ORP) were noticeably higher in summer surface water than those in winter surface water. The results revealed clear seasonal differences in the dominant planktonic bacterial phyla that had a relative content greater than 1%. For example, Proteobacteria, Actinobacteria, and Cyanobacteria were the most dominant phyla in both summer and winter samples. However, Deinococcus-Thermus and Tenericutes were two of the dominant planktonic bacterial phyla that were only present in summer surface water, whereas Gemmatimonadetes was one of the dominant planktonic bacterial phyla present only in winter surface water. Further, the structure of the planktonic bacteria also varied based on the changing of dominant operational taxonomic units (OTUs). Second, the different environmental conditions between winter and summer, especially the exchange process between ice and water, not only caused obvious differences in the eutrophication of surface water but also led to different responses of the dominant bacteria phyla to the content changes in P, EC, DO, COD, ice thickness, etc. For example, the TSI (TP) proxy had higher correlations with changes in the contents of Proteobacteria, Actinobacteria, and Cyanobacteria in ice samples than those in winter and summer surface water samples. Finally, by coupling these findings with the results of sample clustering and typing, we concluded that the dominant bacteria were mainly affected by changes in the internal environment (such as the migration of different P forms, ice thickness, etc.) caused by the freezing process in ice samples. However, the dominant bacteria were mainly affected by changes in the external environment (such as depth, TDS, etc.) in winter and summer water samples.