Microbial Community Assembly Differs Across Minerals In Tengchong Hot Springs,Yunnan Province

Minerals provide physical niches and supply nutrients or serve as electron donors/acceptors for microorganism survival and growth,and thus minerals and microbes co-evolved.Yet,little is known about how microbial species and sediment minerals interact with each other in hot springs and to what extent mineralogical composition influence microbial community composition and diversity.Here the influences of environmental factors on thermophiles in Tengchong hot springs were revealed by network analysis of field samples,as well as in-situ microcosm experiments with minerals.A molecular ecological network was constructed based on high throughput sequencing data of 16 S r RNA gene,with combination of water geochemistry and sedimentary mineralogical compositions.Six modules were identified and this highly modular network structure represent the microbial preference to different abiotic factors,consequently resulting in niche partitioning in sedimentary communities in hot springs.Diverse mineralogical compositions generated special niches for microbial species and aragonite was identified as a key node in a mineral-dominated module.In addition,clay minerals,sulfate minerals,and silicate minerals also affect the interaction between thermophiles to varying degrees.To confirm the effects of these minerals on specific microbial communities,the in-situ microcosm experiments with four minerals(aragonite,albite,K-feldspar,and quartz)and spring water were conducted in a silicate-hosted alkaline spring(i.e.,Gmq)and a carbonate-hosted neutral hot spring(i.e.,Gxs)for 70 days.Different microbial preferences were observed for mineral types(carbonate versus silicate).Compared with the in-situ water and silicate microcosms,archaeal genera Sulfophobococcus and Aeropyrum within the order Desulfurococcales were enriched on the surface of aragonite microcosms in Gmq spring.Sulfophobococcus was also accumulated in Gxs aragonite microcosms,but the contribution to overall dissimilarity is much lower than that in Gmq spring.Besides,Caldimicrobium was a bacterial genus enriched in Gxs aragonite microcosms,in contrast to in-situ water and silicate microcosms,whereas Candidatus Kryptobacter and Thermus were more abundant in silicate microcosms.It follows that the mineral colonizing microbial community is determined by both external factors(surrounding environment)and intrinsic factors(mineral types).The differences in microbial accumulations among different mineral types in the same spring implied that mineral chemistry may exert extra deterministic selective pressure in drawing certain species from the bulk water communities,in addition to stochastic absorption on mineral surface.Subsequently,in-situ cultivation experiments of 11 different types of minerals in low-temperature acidic hot spring(i.e.,WGT)and high-temperature alkaline hot spring(i.e.,GMQ)showed that microorganisms were attached to the mineral surface in molecular signal transmission.By analyzing high-throughput sequencing by 16 S r RNA genes,the composition and diversity of microbial communities on different mineral surface were significantly different.Based upon those result,we also highlight the impacts of minerals on impact the metabolic functions of colonizing microbial communities.Taken together,our results highlight the special niche partitioning determined by mineralogical compositions and further confirm that minerals could be used as “fishing bait” to enrich certain rare microbial species.In addition,different mineral types affect the structural diversity and metabolic functions of the hot springs' microbial community.