Interactions between Saccharomyces cerevisiae and Bacillus licheniformis and interaction mechanisms based on proteomic analysis

Abstract:

[Objective] To better understand the behavior of microbial community during Chinese Maotai-flavor liquor fermentation, we studied the interaction between two functional strains, Saccharomyces cerevisiae and Bacillus licheniformis. [Methods] S. cerevisiae and B. licheniformis were tested in single and mixed culture. Biomass, ethanol and organic acid production were determined during the fermentation. Two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) coupled with matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) was used to analyze and identify differentially expressed protein of S. cerevisiae in single and mixed culture. [Results] S. cerevisiae showed a negative effect on B. licheniformis growth and the growth of itself was barely influenced. However, ethanol, pyruvic acid, lactic acid, malic acid, tartaric acid and succinic acid produced by S. cerevisiae in mixed culture have increased by 11.8％, 56.8%, 24.3%, 36.3%, 27.7% and 48.2% compared with its single culture, respectively. Citric acid yield was reduced by 35.1%. Proteomic profile of S. cerevisiae indicated that 69 spots (differential ratio>2) were differentially expressed in mixed culture. Among them, 24 protein spots were identified, including protein related to glycolysis, ethanol fermentation, cell wall integrity, and stress response. [Conclusion] B. licheniformis affected ethanol and organic acid metabolism of S. cerevisiae. That was significant for liquor quality and microbial interactions. Proteomic analysis of the responses of S. cerevisiae to mixed culture allows a deeper understanding of interaction mechanisms between both strains and will promote the understanding of the microbial community during Chinese Maotai-flavor liquor fermentation.