Characteristics and Quality of Japanese Traditional Fermented Soybean (Natto) from a Low-phytate Line

Widely Targeted Metabolomics Revealed the Metabolic Basis of Physiological Function and Flavor of Natto

Background: Natto is a fermented product derived from soybeans through the action of Bacillus subtilis natto, possessing various pharmacological and health-promoting properties. However, due to the absence of large-scale and systematic investigations into its metabolite profile, the mechanisms governing the biological functions and flavor characteristics of natto remain incompletely elucidated. Methods: In this study, a comprehensive, widely targeted metabolome analysis was conducted using UHPLC-MS/MS to compare soybeans and natto. Results: A total of 569 metabolites were identified, of which 160 exhibited differential expression between natto and soybeans, including 28 amino acids and their derivatives, 19 flavonoids, 18 alkaloids, and 10 nucleotides and their derivatives. Pathway enrichment analysis further demonstrated significant differences in the metabolic pathways between natto and soybeans, with these 160 differentially expressed metabolites primarily distributed across 40 metabolic pathways. KEGG pathway enrichment analysis of natto metabolites revealed that the majority of these mapped to three key metabolic pathways. Variations in the content of flavonoids and alkaloids, as well as changes in amino acid and saccharide composition and abundance, were found to collectively contribute to the distinctive flavor and biological functionality of natto. Conclusions: This study lays the foundation for future efforts to enhance the quality of natto.

Natto: A medicinal and edible food with health function

Natto is a soybean product fermented by natto bacteria. It is rich in a variety of amino acids, vitamins, proteins and active enzymes. It has a number of biological activities, such as thrombolysis, prevention of osteoporosis, antibacterial, anticancer, antioxidant and so on. It is widely used in medicine, health-care food, biocatalysis and other fields. Natto is rich in many pharmacological active substances and has significant medicinal research value. This paper summarizes the pharmacological activities and applications of natto in and outside China, so as to provide references for further research and development of natto.

Nutritional evaluation and transcriptome analyses of short-time germinated seeds in soybean (Glycine max L. Merri.)

Germination is a common practice for nutrition improvement in many crops. In soybean, the nutrient value and genome-wide gene expression pattern of whole seeds germinated for short-time has not been fully investigated. In this study, protein content (PC), water soluble protein content (WSPC), isoflavone compositions were evaluated at 0 and 36 h after germination (HAG), respectively. The results showed that at 36HAG, PC was slightly decreased (P > 0.05) in ZD41, J58 and JHD, WSPC and free isoflavone (aglycones: daidzein, genistein, and glycitein) were significantly increased (P < 0.05), while total isoflavone content was unchanged. Transcriptomic analysis identified 5240, 6840 and 15,766 DEGs in different time point comparisons, respectively. GO and KEGG analysis showed that photosynthesis process was significantly activated from 18HAG, and alternative splicing might play an important role during germination in a complex manner. Response to hydrogen peroxide (H2O2) was found to be down regulated significantly from 18 to 36HAG, suggesting that H2O2 might play an important role in germination. Expression pattern analysis showed the synthesis of storage proteins was slowing down, while the genes coding for protein degradation (peptidase and protease) were up regulated as time went by during germination. For genes involved in isoflavone metabolism pathway, UGT (7-O-glucosyltransferase) coding genes were significantly up regulated (40 up-DEGs vs 27 down-DEGs), while MAT (7-O-glucoside-6''-O-malonyltransferase) coding genes were down regulated, which might explain the increase of aglycones after germination. This study provided a universal transcriptomic atlas for whole soybean seeds germination in terms of nutrition and gene regulation mechanism.