Unique Habitat of Karst Tiankengs Changes the Taxonomy and Potential Metabolism of Soil Microbial Communities.

Microbial communities in karst ecosystems have been extensively studied. However, in a class of deep-lying habitats with unique climates (karst tiankeng), the structure and ecological functions of microorganisms receive little attention, which is essential for understanding the biogeochemistry of karst tiankeng. Herein, microorganisms from inside (ITK) and outside (OTK) karst tiankengs were analyzed by high-throughput sequencing and multivariate statistical analysis. The results showed that the structure and function of soil bacterial communities inside and outside karst tiankengs were significantly different. The ITK microbial communities presented significantly higher Shannon diversity due to the abundant nutrients in karst tiankeng soil. Random molecular ecological network analysis revealed that the ITK network was simpler and more vulnerable and may be susceptible to environmental changes. More positive links within the network indicate that microorganisms adapt to the karst tiankeng through synergies. The keystones in karst tiankeng were mainly involved in the decomposition of soil organic matter and carbon/nitrogen cycles. Although soil total phosphorus and available potassium regulate microbial community structure variation, dispersal limitation is the predominant ecological process within the microbial community in karst tiankeng. In addition, the functional profiles of the microbial communities reveal that some human diseases (such as infectious diseases) exist in OTK. Collectively, these findings have enhanced our understanding of microbial interactions, ecological functions, and community composition processes in karst tiankeng ecosystems.