Metagenomic analysis of microbial community succession during the pickling process ofZhacai(preserved mustard tuber) and its correlation withZhacaibiochemical indices

BACKGROUND Industrial FulingZhacaiis pickled by a method summarized as 'three times pickled and pressed', in which raw mustard tubers are subjected to three stages of pickling in different salt concentrations, with a pressing operation at the end of each stage to remove brine. This study used Illumina MiSeq technology and multivariate statistical analyses to investigate microbial community succession during the pickling process and its correlation withZhacaibiochemical indices. RESULTS A total of 19 phyla, 208 genera, and 295 species of bacteria were identified.Lactobacilluswas the dominant genus of bacteria in all three stages andLactobacillus sakeiwas the dominant species in the first and second stages. A total of six phyla, 200 genera and 301 species of fungi were also identified. According to a PICRUSt2 prediction, the main functions of the bacterial and fungal communities were carbohydrate and protein metabolism, while alcohol metabolism was also a function of fungi. Nine bacterial genera closely correlated withZhacaibiochemical indices:Acinetobacter,Pseudomonas,Pedobacter,Erwinia,Lactobacillus,Chryseobacterium,Flavobacterium,Duganella,andPaenarthrobacter. Six genera of fungi correlated closely:Penicillium,Cystobasidium,Cladosporium,Plenodomus,Aspergillus,andSimplicillium. All these genera probably originated from the surface microorganisms of raw mustard tuber. CONCLUSION This study reveals the succession patterns of microbial community structures during the pickling process of industrialZhacaiand infers the core functional flora, providing reference data forZhacaipickling process control. (c) 2020 Society of Chemical Industry

Automated summary

This study investigated the microbial community succession patterns during the pickling process of industrial Zhacai, and identified the core functional flora, providing reference data for pickling process control. The dominant bacteria genus was Lactobacillus, with Lactobacillus sakei being the dominant species in the first and second stages. Nine bacterial genera and six fungal genera were closely correlated with Zhacai biochemical indices.