Microbial Diversity In Freshwater Of The Chishui River In Maotai Town, China

Chishui River, a larger tributary of the upper Yangtze River, is named after its high sediment concentration and crimson colour in summer. As the source of Maotai liquor, protecting the ecological environment of the upper Chishui River from destruction is necessary. The purposes of this study are to analyze the microbial diversity and dynamic change of microbial community in different seasons in Chishui River and to analyze the environmental carrying capacity and river self-purification capacity of Maotai areas from the perspective of environment microbiology, to provide a reference for the environmental management policies. In this study, we combined the traditional culture method, high-throughput sequencing technology and real-time PCR technology to analyze the microbial community in Chishui River, and obtained the following conclusions:(1) In the part of culturable microorganism, we obtained more than800strains, which belong to357species,122genera and5phyla. The microbial diversity was very rich in the samples and the dominant genera included Brevundimonas, Flavobacteriumand Bacillus. Eight strains of novel species were isolated from Chishui River, two of which were identified through polyphasic taxonomy analysis method.(2) By high-throughput sequencing analysis, we obtained25137reads of bacterial16S rRNA gene sequence, which belonged to4351OTUs and391genera. The dominant bacterial phyla are Proteobacteria, Firmicutes, Bacteroidetes, Actinobacteria and unclassified. We obtained43465reads of archaeal16S rRNA gene sequence, which belonged to5586OTUs and20genera. The dominant archaeal phyla in the samples were Euryarchaeota and Crenarchaeota, including Methanosarcina, Methanospirillum, Methanobacterium, Methanosphaerula, Methanosaeta, Methanoregulaand unclassified. All of the archaea in samples are related to methanogenesis.(3) The bacterial diversity showed summer>winter>spring or fall and the bacterial abundance showed that spring or summer> fall or winter, suggesting that in summer the bacteria were the most rich and abundant; in winter that were not abundant but still rich. The results of high-throughput sequencing indicated that microbial diversity in upstream was slightly higher than that in downstream; however, the results of qPCR indicated that microbial abundance in downstream was clearly higher than that in upstream, suggesting that producing and living of Maotai town had affected on Chishui River that led to slight decrease of richness and increase of some microbe.(4) Methanogenic archaea distribute widely that could metabolize organic matterand play roles in sewage treatment and river self-purification. In the results of high-throughput sequencing, archaeal diversity was highest in summer. The seasonal variation of archaea was not higher but the difference of archaea between upstream and downstream was higher, compared with that of bacteria. Archaeal diversity in downstream was higher than that in upstream, suggesting organic matter content was higher in downstream river.