Dynamic changes in the bacterial communities and metabolites of Moringa oleifera leaves during fermentation with or without pyroligneous acid

Abstract

In this study, Moringa oleifera leaves (MOL) were fermented with or without pyroligneous acid (PA) for 3, 7, 14, and 30 days. PA addition enhanced the contents of acetic acid and true protein (P < 0.01) and decreased pH (P < 0.01) and the contents of coliform bacteria, nonprotein nitrogen (P < 0.01), and ammonium nitrogen (P < 0.01). With the addition of PA, the abundance of Lactobacillus increased, but the abundance of Enterobacter decreased. A total of 754 metabolites were identified. In the MOL fermented with PA, the contents of apigenin, arbutin, 2-methoxy-4-vinyl phenol, and 4-methoxy cinnamic acid increased, while the content of skatole decreased compared with the contents for the MOL fermented without PA. The detected metabolites were correlated with bacterial communities, especially Lactobacillus and Weissella. In conclusion, the addition of PA improves the fermentation quality and protein preservation and affects the microbial communities and metabolites of fermented MOL.