STUDY ON ISOLATION AND SELECTION OF HEAT-RESISTANT LACTIC BACTERIA FROM THE NATURAL FERMENTED RESOURCES
Abstract
The study aims to isolate and select lactic acid bacteria strains with good thermotolerant capacity. The study isolated six strains of lactic acid bacteria from natural fermented resources. Among these bacterial strains, one strain of lactic acid bacteria with the highest lactic acid fermentation activity and the best heat resistance was selected. Specifically, the selected bacterial strain after being fermented in MRS medium for 36 hours at 47oC produced the lactic acid concentration of 1.75 mg/ml. Besides, the selected bacterial strain is also capable of growing at 51oC. The identification of selected bacteria based on the comparison results of 16Sr RNA gene sequence produced the similarity rate with Lactiplantibacillus pentosus species of 100%. Research results also show that if cultured in an MRS medium, the growth curve of Lactiplantibacillus pentosus strain is divided into 4 phases: starting phase (0-3) hours, growing phase [3-27) hours, equilibration phase from [27-33] hours, the decline phase after 33 hours of culture.