Dynamics of Microbial Community Structure and Metabolites during Mulberry Ripening

Abstract

In this experiment, we explored the chemical composition and community structure of Mulberry “Wuhedashi” (Morus alba L., hereinafter referred to as WHDS) in different stages and obtained data support for its resource utilisation. Five ripening stages were established: S1, deep-red stage; S2, red with black stage; S3, black with red stage; S4, black stage; S5, overripe stage. The results showed that there were significant differences in the indicators of WHDS in the different stages. Immature WHDS contains high levels of amino acids (2.14 ± 0.15 mg/g), organic acids (43.10 ± 0.75 mg/g), K (3019.52 ± 78.00 mg/L), and Ca (1617.86 ± 24.45 mg/L) and is an important source of amino acid and mineral supplementation for the body. Total phenolic compounds (26.15 ± 0.43 g/L), total flavonoids (2.46 ± 0.03 g/L), total anthocyanins (587.60 ± 7.38 mg/L), the ABTS radical scavenging rate (94.20 ± 2.18%), the DPPH radical scavenging rate (95.13 ± 1.44%), and total flavour compounds (1279.09 ± 33.50 mg/L) peaked at S4, which is the optimal stage for the consumption and processing of WHDS. High-throughput sequencing identified 10 dominant genera, including Bacillus, Brevibacterium, Pseudomonas, and Tatumella. Nesterenkonia was the most highly associated micro-organism. Bacterial genera such as Pantoea and Pseudomonas were significantly positively correlated with esters, enhancing the floral and fruity flavours of wine. The results of the study revealed the characteristics of WHDS in different stages, which can help to target the development of nutritious mulberry derivatives and provide a reference for enhancing the added value of mulberry.