Exploring the mechanism of Weissella cibaria cooperating with Lactiplantibacillus plantarum to improve volatile flavor of Sichuan pickle using dialysis membranes

This study established a laboratory-scale dialysis membrane isolation device to explore bacterial cooperative fermentation mechanisms and their effects on pickle fermentation quality. Results showed the dialysis membranes with molecular weight cut-off of 1000 kDa was particularly effective in restricting Lactiplantibacillus plantarum LP067 and Weissella cibari a WC018 while facilitating nutrient and metabolite exchange. Our results showed that using dialysis membranes did not significantly affect the quality of cooperative fermentation Sichuan pickles. Using this dialysis membrane system, the Sichuan pickles of mono-inoculation or co-inoculation of Lactiplantibacillus plantarum LP067 or Weissella cibaria WC018 of the basic physicochemical index, organic acids, volatile flavor compounds, and sensory properties were evaluated. Compared to mono-inoculation of Lactiplantibacillus plantarum LP067 or Weissella cibaria WC018, co-inoculation accelerated acetic and lactic acids production, also significantly promoted the generation of volatile flavor compounds, such as esters, aldehydes, and ketones, including isobutyl formate, ethyl palmitate, ethyl acetate, 1-octen-3-ol and benzaldehyde. Meanwhile, cooperative fermentation increased the aroma complexity of Sichuan pickle, and thus to improve its overall sensory acceptability. The transcriptomic results revealed that W. cibaria WC018 enhanced the levels of genes related to lactic acid and acetic acid metabolism in L. plantarum LP067. The results provided a novel perspective for the isolation of individual strains in the cooperative fermentation process and laid a theoretical foundation to further explore the cooperative fermentation mechanisms among the same type strains.