Bacterial characterization of fermented sweet potato leaves by high-throughput sequencing and their impact on the nutritional and bioactive composition

Abstract

Bacterial, nutritional, and bioactive compositions of fermented sweet potato leaves (SPL) were investigated. Three samples were utilized: control (C), natural fermentation (NF), and probiotic fermentation (PF). Bacterial composition was assessed by high-throughput sequencing. Lactobacillus plantarum and Enterococcus durans were identified in NF. Lactobacillus plantarum was also found in PF, showing a relative abundance of 90.2%. Polyphenol composition determined by HPLC changed considerably during NF decreasing its concentration to a value of 6.69 mg/g dw compared to the value found in C (42.77 mg/g dw). PF maintained the polyphenol concentration (38.64 mg/g dw) but some interconversion between polyphenols seems to occur. ABTS radical scavenging capacity value was similar in C and PF, demonstrating no changes in antioxidant activity. During PF antioxidant activity was maintained, and angiotensin-converting enzyme inhibitory activity was even improved. Fermentation was a good process for SPL. According to the parameters assessed, PF was better than NF. Novelty impact statement: The effect of natural and probiotic fermentations on the bacterial composition, nutritional, and bioactive composition of sweet potato leaves was compared. Results showed that fermentation was a good process for sweet potato leaves. According to the parameters assessed, probiotic fermentation was better than natural fermentation.