Characterizing the impact of species/strain-specific Lactiplantibacillus plantarum with community assembly and metabolic regulation in pickled Suancai.

To investigate the colonization and impact of the specific Lactiplantibacillus plantarum strains, four isolated strains were applied in pickled Suancai which is a traditional pickled mustard (Brassica juncea). Results showed that strain-8 with the highest lactic acid bacteria (LAB) counts and acetic acid (p < 0.05). There were 11.42 % ∼ 32.35 % differential volatile compounds detected, although nitriles, esters, and acids were predominant. L. plantarum disturbed the microbial community, in which the microbial composition of strain-11 was most similar to the naturally fermented sample. Amino acids, carbohydrate metabolism, and metabolism of cofactors and vitamins were the main functional classes because of the similar dominant microbes (Lactiplantibacillus and Levilactobacillus). The functional units were separated based on NMDS analysis, in which bacterial chemotaxis, amino acid-related units, biotin metabolism, fatty acid biosynthesis, and citrate cycle were significantly different calculated by metagenomeSeq and Benjamin-Hochberg methods (p < 0.05). The contents of most flavor compounds were consistent with their corresponding enzymes. In particular, glucosinolates metabolites were different and significantly related to the myrosinase and metabolic preference of LAB. Therefore, this study revealed the impact mechanism of the specific L. plantarum strains and provided a perspective for developing microbial resources to improve the flavor diversity of fermented vegetables.