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The distributional characteristics of microorganisms in karst cave ecosystems have been widely studied. However, in such a dark, humid, and oligotrophic habitat, studies on the differences in carbon-sequestering bacteria in multiple habitats are limited. Therefore, to learn the distribution characteristics of carbon-sequestering colonies in cave habitats and their correlation with habitat factors (e.g., pH, Ca2+, Mg2+, etc.), samples from five cave habitats (weathered rock walls, underground river water, drips, sediments, and air) were collected from the twilight and dark zones of Shiziyan Cave (CO2 concentration 5385 ppm). The results of high-throughput sequencing and statistical analyses showed that there were significant differences in the distribution of communities in different habitats, with higher abundance in sediments habitat and underground river water habitat, and the dominant phyla of Pseudomonadota (30.53%) and Cyanobacteria (75.11%) in these two habitats. The microbial diversity of the carbon-sequestering microbial community was higher in sediments than in underground river water. The pH, and Ca2+, SO 4 2 − , and NO 3 − concentrations can alter the diversity of carbon-sequestering microbes, thereby affecting carbon cycling in caves. Carbon metabolism analyses suggest that microbes in the habitat can cooperate and coexist by participating in different carbon metabolic pathways. These results expanded our understanding of carbon-sequestering microbial communities in cave systems and their responses to the environment. [ABSTRACT FROM AUTHOR]

Unraveling the assembly mechanism is a core research topic of microbial ecology. Abundant and rare microbial communities are crucial for diversity, function and host health in a given ecosystem, but few studies focused on their assembly strategies. Here, we explored the microbial diversity of abundant and rare communities of water, shrimp intestine and sediment habitats in the shrimp cultural ponds. Our results found that the numbers of rare operational taxonomic units (OTUs) (6,003, 4,566 and 8,237 OTUs of water, intestine and sediment) was dozens of times more than abundant ones (only 199, 157 and 122 OTUs of water, intestine and sediment). The community diversity of abundant and rare microbial taxa was markedly different, as well as their taxonomic composition. Despite different diversity, similar abundance-occupancy relationship and biogeographic patterns between the abundant and rare microbial communities were observed, with much stronger obvious distance-decay relationships for rare community than abundant community. Furthermore, stochastic processes dominated the community assemblies of both abundant and rare microbial taxa, and deterministic process contributed more microbial community variation to rare taxa than abundant taxa. All the findings advance our understanding on the community assembly strategies of abundant and rare microbial taxa and prompt the contributions of abundant and rare microbial community to the aquatic ecosystems, which will improve aquaculture management strategy.