Evolution-aided improvement of the acid tolerance of Levilactobacillus brevis and its application in sourdough fermentation.

Levilactobacillus brevis is crucial in food fermentation, particularly in sourdough production. However, the cultivation of L. brevis faces a challenge with accumulation of lactic acid, a major inhibitor. We aimed to increase the acid tolerance of L. brevis, an industrial strain for sourdough fermentation. We used the adaptive laboratory evolution (ALE) to obtain lactic acid tolerant strains. The evolved strain's fermentation and metabolite profiles, alongside sensory evaluation, were compared with the parental strain by using various analytical techniques. The ALE approach increased lactic acid tolerance in the evolved strain showing an increased growth rate by 1.1 and 1.9 times higher than the parental strain at pH 4.1 and 6.5, respectively. Comprehensive analyses demonstrated its potential application in sourdough fermentation, promising reduced downstream costs. The evolved strain, free from genetically modified organisms concerns, has great potential for industrial use by exhibiting enhanced growth in acidic conditions without affecting consumers' bread preferences.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: ‘Kyoung Heon Kim has patent Lactic acid bacteria mutant and culturing method for sourdough fermentation licensed to SPC Group. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.’.
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