Isolation, Identification and Characterization of Lactic Acid Bacteria from Qula in Gannan

To investigate the performance of lactic acid bacteria in Qula in Gannan. In this study, the Qula sample, which was traditionally hand-made by Tibetan herders in Gannan, Gansu Province, was used as the research object. The lactic acid bacteria in the Qula were isolated and identified by pure culture method, and the performance of lactic acid bacteria was studied. The results showed that there were 97 strains of lactic acid bacteria were isolated from 9 Qula fermented under natural conditions. Six strains of lactic acid bacteria were obtained through preliminary screening. The strains were identified by 16S rDNA, strain Q1 was Streptococcus thermophilus, and strain Q2 was Enterococcus durans, strains G1, G2, G3, and G4 were Lactobacillus helveticus. The performance studies on 6 strains showed that the curd time of these 6 strains was between 4~7 h, the titratable acidity during curd was between 73.42~89.38°T, and the acidity of yogurt during the cold storage increased by 14.22 to 20.93°T, the viable counts were all greater than 10⁷ CFU/mL, the viscosity was 5.42~7.84 Pa·s. The research results can provide a theoretical basis for the application of lactic acid bacteria.