Characterization of Structural and Functional Changes in Bacterial Communities During Enzyme Fermentation

The use of agricultural enzymes is a new research direction for addressing soil problems. Microbial community structure and composition during fermentation are influenced by environmental conditions, making them complex to characterize. Here, the bacterial community structure in the middle and late stages of compost fermentation, with and without the addition of enzymes, was analyzed using 16 S rRNA high-throughput sequencing technology. Additionally, the secondary functional traits of microbial communities were identified using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. In liquid fermentation, the addition of exogenous enzymes reduced the number of microbial species. After an extended period, the dominant bacterial species emerged, with the relative abundance of Proteobacteria reaching 70%. There was a significant difference between the abundance of bacterial species (p = 0.04). However, in compost, as the fermentation duration increased, the bacterial abundance species increased, and the relative abundance of the main bacterial phyla tended to be uniform. Bacterial species abundance did not differ significantly at the phylum (p > 0.05) or genus (p > 0.05) level. According to the KEGG database, the top five most abundant metabolic pathway functional genes were related to the metabolism of substances and the energy required to maintain basic microbial life activities: carbohydrate metabolism, amino acid metabolism, metabolism of cofactors and vitamins, metabolism of terpenoids and polyketides, and metabolism of other amino acids. Exogenous enzyme supplementation alters microbial community succession and metabolic functions during composting and liquid fermentation. The results of this study provide a theoretical reference for the application of enzymes and traditional compost in agricultural production.