Mycobiota of highly-preserved and easily-spoiled soybean pastes-what are their roles?

Effective preservation of fermented soybean pastes is critically dependent on their microbial communities. In this study, the fungal assemblages of highly-preserved (HP) and easily-spoiled (ES) soybean paste samples were analyzed and compared mainly with Illumina sequencing of both mycobiota ITS amplicon and metagenomic functional annotation. The results showed that fungal communities of two types soybean pastes were distinct and had different α-diversity and β-diversity characteristics. The phylum Ascomycota was predominant in all samples, with Candida, Aspergillus, and Penicillium being the most abundant genera. The HP group exhibited greater richness and diversity compared to ES samples, and the relative abundance of specific fungal taxa varied significantly between the two groups. Additionally, functional annotation revealed differences in metabolic categories, with HP samples having higher levels of functions related to amino acid transport and metabolism, cell cycle control, and signal transduction mechanisms. These results enhance the understanding of the fungal diversity and functional differences of soybean pastes, providing insights that could improve preservation methods, optimize production and storage processes, and ensure the quality of the products.