Study on ethanol tolerance and protease properties of lactic acid bacteria from koumiss in Xinjiang areas

The aim of the study was to investigate the ethanol tolerance and the differences of protease activity of different lactic acid bacteria strains, which were isolated and identified traditionally from Xinjiang loumiss.After different concentrations of ethanol stress for 12 h, the results showed the stress tolerance of 5 different strains from high to low were Lactobacillus fermentum, Pediococcus pentosaceus, Lactobacillus plantarum, Enterococcus faecium, Pediococcus acidilactici among the 21 strains initially isolated, one of the which could withstand the highest concentration of 13% ethanol stress.We concluded that all strains could produce protease by measuring the proteolytic activity of the protease, it was worth mentioning that the diameter of the hydrolytic ring of Pediococcus acidilactici was the largest, which was 13.1 mm and the self-solubility was 36.4%.Results have also shown that the relationship between ethanol tolerance and protease hydrolysis was not significant.