Regulation of auxotrophic lactobacilli growth by amino acid cross-feeding interaction

Microbial interaction plays an important role in the assembly of microbial communities in spontaneous food fermentation. Amino acids are important for the microbial interaction. However, the effect of amino acids on the microbial interaction is still unclear in food fermentation. Here, we studied the cross-feeding of amino acids between Saccharomyces cerevisiae and two lactobacilli species (Limosilactobacillus panis and Lentilactobacillis buchneri) from Chinese liquor fermentation. The inoculation of S. cerevisiae and concentrations of amino acids significantly influenced the growth of two lactobacilli species (P < 0.05). Li. panis and Le. buchneri were respectively auxotrophic of 11 and 4 amino acids through single omission technique experiment. S. cerevisiae would promote the growth of Li. panis and Le. buchneri through excreting their essential amino acids, including valine and isoleucine. Herein, we used response surface methodology to establish a predictive model for the growth of lactobacilli species by the regulating factors, the initial concentrations of valine and isoleucine, and inoculum size of S. cerevisiae. Based on the optimized levels of the three factors, the biomass of Li. panis increased from 6.5 ± 0.3 to 7.6 ± 0.1 log₁₀ cells/mL, and the biomass of Le. buchneri increased from 7.2 ± 0.2 to 8.4 ± 0.3 log₁₀ cells/mL. This work revealed the interaction pattern between S. cerevisiae and the two lactobacilli species, it would facilitate the regulation of microbial growth in Chinses liquor fermentation.