Bacterial microbiota and metabolic characteristics of traditional Zhangjiajie Jiuqu aromatic ester vinegar in China

Aged vinegars are popular acidic condiments worldwide, used for their flavour and nutritional value; they also have a rich microbial diversity. This study combined the ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF-MS) technology with Pacific Biosciences (PacBio) single-molecule real-time (SMRT) sequencing to analyze the microbial population and associated metabolism in six traditional Zhangjiajie Jiuqu aromatic ester vinegars (JAEVs) in China. A total of 265 species and subspecies from 170 bacterial genera and 14 phyla were identified; among these Lactococcus lactis (18.23%) and Acinetobacter johnsonii (17.18%) were the predominant species. A total of 1352 metabolites were detected in the metabolomes of all samples. In addition, occurrence of 40 metabolites detected were significantly different among six samples. Based on correlation analyses between the prevalent bacterial species and main differentially recorded metabolites, we conclude that there were significant correlations (P < 0.05) between 20 metabolites and five bacterial species. Limosilactobacillus fermentum and Hyphomicrobium zavarzinii were the main regulatory strains caused differential metabolites. Some potential functional metabolites were also identified, mainly chlorogenic acid and trans-piceid. This study revealed the relationship between the unique flavour of JAEVs and the microbial community, and provided a basis for industrial production of traditional aged vinegar.