Atmospheric and room temperature plasma mutagenesis and malolactic fermentation of highly acid-tolerant Oenococcus oeni

Abstract:

[Objective] To breed highly acid-tolerant strains of Oenococcus oeni and study their stress tolerance and malolactic fermentation (MLF) performance.[Methods] The mutagenesis of O. oeni SD-2a was carried out with the atmospheric and room temperature plasma (ARTP) method. The ethanol tolerance of the mutants and the MLF performance of the mutants in simulated wine and wine were investigated. [Results] After ARTP mutagenesis, five acid-tolerant mutants with high β-glucosidase activity were isolated by subculture under stress (pH 3.0). The mutants showed strong ethanol tolerance at high ethanol concentrations. Among them, the mutant ARTP-2 had the highest β-glucosidase activity and l-malic acid cumulative degradation in the simulated wine. Moreover, it demonstrated faster l-malic acid degradation rate in wine than O. oeni SD-2a and completed MLF on day 18. The total concentration of aroma components in the wine fermented by ARTP-2 was significantly higher than that by O. oeni SD-2a. [Conclusion] The mutant ARTP-2 had strong stress tolerance and MLF performance and played a positive role in wine aroma. The findings laid a foundation for the further development of high-quality commercial fermenters for MLF.