Taxonomical and functional diversity of microbial communities in two hot springs of the Baikal rift zone

Abstract

The Baikal Rift Zone hosts many hot springs with a wide range of temperature and physical-chemical conditions, which may harbour different niches for the distribution of microbial communities. We investigated microbial community composition and their functional activity in two alkaline hot springs with a temperature range of 34.4 to 73.6°C. Comparative analysis of the composition of the dominant taxa showed significant differences depending on the collection sites. In the community of high-temperature zones with a water temperature of 55-64°C, a high proportion of thermophilic bacteria Acetothermia (up to 57.9%), Deinococcus-Thermus (up to 50%), and Aquificae (up to 10.8%). Proteobacteria (29-77%) and Firmicutes (15-26%) dominate in the sulphide-free Garga spring (73-75°C). The functional analysis of the microbial community showed that the primary producers are cyanobacteria, anoxygenic phototrophs, and chemolithotrophic bacteria. At the terminal stages of the mineralization of organic matter, sulphate-reducing bacteria are the main destructors in the microbial communities in hot springs. The cyano-bacterial and sulfidogenic microbial communities play an important role in the formation of geochemical barriers and mineral formation.