Abstract: In order to carry out the study on seasonal changes in the diversity of culturable bacterial communities in water bodies of Namco Lake, water samples were collected in summer 2020, spring 2021 and autumn 2021, respectively. The isolation and purification of bacteria were performed by spread plate method and plate four zone streaking method, respectively. Strains were identified by 16S rDNA gene sequencing technology combined with classical taxonomy method, and the data were processed and analyzed by using relevant statistical softwares. A total of 1877 culturable bacteria strains were isolated from water samples of Namco Lake collected in three seasons, which belong to 87 species, 34 genera, 26 families, 15 orders, 7 classes and 4 phyla. The total bacterial abundance was highest in summer and lowest in autumn, while the 3 community diversity indices were highest in autumn and lowest in summer. The results of PCoA and other analyses collectively show that bacterial community structure similarity was high between spring and summer, while it was low between spring and autumn, summer and autumn. The result of the CCA indicates that total dissolved solids was the most influential physicochemical parameter on the distribution of bacterial community in different seasons. The result of the Mantel test indicates that the differences of total dissolved solids, temperature, chemical oxygen demand, and turbidity in different seasons were significantly (P<0.001) correlated with the differences of bacterial community structure. This study initially investigated the seasonal changes in the diversity of culturable bacterial communities in the water body of Namco Lake, which is of great significance for the conservation of lake ecosystems on the Tibetan Plateau and the exploitation and utilization of bacterial resources among them.

Key words: Namco, bacteria, physicochemical parameters, lake, Tibetan Plateau