Starch utilization characteristics of lactic acid bacteria isolated from Daqu

Abstract:

[Background] Lactic acid bacteria (LAB) are important microorganisms which affect the texture and flavor of fermentation foods such as sourdough and steamed bun. Amylolytic LAB have enormous application possibilities owing to their ability to colonize in flour. [Objective] To screen amylolytic LAB and study their starch utilization characteristics. [Methods] The medium with starch as carbon source was used to enrich target strains from Daqufor strong aromatic Chinese spirit, followed by testing the starch hydrolysis ablility. Then, expression level of amylase in the yielded strain and the enzyme activity were determined. [Results] Daqu which had been stored for 3‒6 months was optmal for screening the bactia. Amylolytic LAB can be quickly screened out by subculture with batter. The yielded strains were dominated by Lactobacillus plantarum and Lactobacillus paralimentarius. The starch utilization characteristics and amylase activity in the amylolytic L. paralimentarius LBM12001 were analyzed. The findings showed that it can hydrolyze starch at 10 g/L and well colonize in batter. The α-amylase and maltogenic amylase were extracellular enzymes. The specific enzyme activity of maltogenic amylase reached 1 240 U/mg at pH 3.5.[Conclusion] We developed a method to enrich about screen amylolytic LAB from Daqu for traditional Chinese spirit and a method for evaluating the starch hydrolysis ability, and screened out the extracellular maltogenic amylase-secreting strain which had great potential in the production of sourdough, steamed bun, and other fermentation foods.