Structure and Function of Bacterial Communities in Petrifying Springs Moss Biofilms and Tufa Sediments

The petrifying springs wetland system possesses unique geo-ecological values but is currently at risk of degradation due to declining water quality in recent years. Moss and its associated biofilm play crucial roles in promoting the tufa deposition process; however, the impact of changes in water nutrients—particularly nitrogen and phosphorus—on biofilm function and the tufa deposition mechanism remains unclear. This study focused on the Petrifying Springs Wetland in Xiangzhigou, Guizhou Province, and aimed to investigate the physicochemical indicators of its water as well as the bacterial communities present in both tufa sediments and four dominant moss biofilms. By employing alpha and beta diversity analyses along with functional assessments, the study examined the structural and functional differences between the bacterial communities in biofilms and sediments. Additionally, the research explored how these bacterial communities respond to changes in water quality through the integration of Mantel and RDA analyses. The findings revealed significant differences in the composition and function of bacterial communities between biofilms and sediments, with alpha diversity being notably higher in sediments compared to biofilms. The structure and function of bacterial communities in four moss biofilms were significantly different. The α diversity of bacterial communities in biofilms is as follows: Brachythecium curtum (Lindb.) Limpr > Cratoneuron filicinum (Hedw) Spruce var. filicinum > Hydrogonium majusculum (C. Muell.) Chen > Fissidens grandifrons Brid. Furthermore, the biofilms of B. curtum and C. filicinum var. filicinum exhibit significant enrichment of nitrogen metabolism functions. The biological metabolic activities of bacterial communities in biofilms and sediments contribute significantly to the formation of tufa landforms by facilitating the deposition of calcium carbonate. Additionally, these activities are essential to the biogeochemical cycle within the wetland ecosystem of petrifying springs. This study offers valuable insights into the ecological role of moss biofilm in the petrifying springs wetland ecosystem and establishes a foundation for the effective management of tufa resources.