Different Responses of Bacteria and Archaea to Environmental Variables in Brines of the Mahai Potash Mine, Qinghai-Tibet Plateau

Abstract

Salt mines feature both autochthonous and allochthonous microbial communities introduced by industrialization. It is important to generate the information on the diversity of the microbial communities present in the salt mines and how they are shaped by the environment representing ecological diversification. Brine from Mahai potash mine (Qianghai, China), an extreme hypersaline environment, is used to produce potash salts for hundreds of millions of people. However, halophiles preserved in this niche during deposition are still unknown. In this study, using high-throughput 16S rRNA gene amplicon sequencing and estimation of physicochemical variables, we examined brine samples collected from locations with the gradient of industrial activity intensity and discrete hydrochemical compositions in the Mahai potash mine. Our findings revealed a highly diverse bacterial community, mainly composed of Pseudomonadota in the hypersaline brines from the industrial area, whereas in the natural brine collected from the upstream Mahai salt lake, most of the 16S rRNA gene reads were assigned to Bacteroidota. Halobacteria and halophilic methanogens dominated archaeal populations. Furthermore, we discovered that in the Mahai potash mining area, bacterial communities tended to respond to anthropogenic influences. In contrast, archaeal diversity and compositions were primarily shaped by the chemical properties of the hypersaline brines. Conspicuously, distinct methanogenic communities were discovered in sets of samples with varying ionic compositions, indicating their strong sensitivity to the brine hydrochemical alterations. Our findings provide the first taxonomic snapshot of microbial communities from the Mahai potash mine and reveal the different responses of bacteria and archaea to environmental variations in this high-altitude aquatic ecosystem.

Prokaryotic Microbial Diversity Analysis and Preliminary Prediction of Metabolic Function in Salt Lakes on the Qinghai–Tibet Plateau

“…Similarly, Loubna et al isolated and identified more archaea in the Great Salt Lake, which has significant salinity differences between the northern and southern regions [30]. Xie et al also demonstrated that the diversity and composition of archaea in the brines of the Mahai potash mine on the Tibetan Plateau are mainly influenced by the chemical properties of the hypersaline water [31]. While unique microbial community distributions do exist, our study suggests that salinity is the primary driver of species composition differences in lake ecosystems, whereas other factors such as pH, nutrition, and temperature usually occupy the second place in microbial community construction [13,29,32].…”