Priming effect of different DOM components on the degradation of organic matter during the decomposition period of Phragmites australis: Microbiological mechanisms

Dissolved organic matter (DOM), as nutrient source for the survival and metabolism of microorganisms, has a significant impact on the decomposition process of aquatic plants. However, the priming effects (PE) of different DOM components on plant degradation and the mechanisms of microbial community composition remain unclear. In this study, the microenvironment constructed by Phragmites australis, DOM, and microorganisms. The PE of DOM components on the decomposition of aquatic plants and its microbial mechanisms were investigated through microbial sequencing technology and spectral analysis. Results show that adding DOM components alters the overlying water's chemical environment, generating PE of −66 % to 67 % for nitrogen and phosphorus release, with positive PE lasting 1–16 days. Also, adding DOM components yields positive PE up to 414 % for the degradation of the same-type DOM components released during decomposition. The addition of DOM not only directly affected the microbial community but also influenced the community through changes in environmental physicochemical factors. Tryptophan and tyrosine's addition increased the relative abundance of bacterial genera such as Singulisphaera and Paludisphaera, which were significantly correlated with the C1 and C2 components. Compared with amino acids, glucose addition could quickly induce the response of dominant populations. The relative abundance of Bacteroidetes, which decomposes and metabolizes recalcitrant organic matter, increased by up to 23 % with the addition of humic acid. In conclusion, different DOM components could affect organic matter degradation during the decomposition of aquatic plants by regulating microbial community structure, which has important implications for understanding matter cycling in lakes.