Abstract
Karst tiankengs are oases in degraded karst landscapes and act as repositories for biodiversity conservation; however, knowledge about the bacterial and fungal structure and function of the karst tiankeng ecosystems is limited. This study investigated the microbial communities in three different tiankeng (nondegraded, moderately degraded, and heavily degraded tiankeng) by Illumina NovaSeq sequencing. We found that the degradation of karst tiankeng can lead to changes in microbial community structure and functions, while there are differences in bacterial and fungal responses. There were significant differences in bacterial and fungal community composition and beta diversity in the three tiankeng soils. Random molecular ecological network analysis results indicated that a more complex and stable bacterial network existed in nondegraded tiankeng, while more complex fungal networks existed in moderately degraded tiankeng. The keystones of Proteobacteria, Actinobacteria, Acidobacteria, Ascomycota, and Basidiomycota played essential roles in maintaining soil function and stability. The functional profiles revealed that tiankeng habitat changes may affect microbial survival strategies, such as increasing gene abundance associated with the carbon cycle. To our knowledge, this is the first report on bacterial and fungal communities in different degrees of karst tiankeng, which provides crucial insights into our understanding of the microbial communities' structure and potential function in karst tiankeng ecosystems.