Isolement et identification des bactéries lactiques autochtones isolés de lait de vache de la région d’Oued Rhiou

Abstract

Lactic acid bacteria are a natural part of our environment and our diet. It has long been recognized that lactic acid bacteria have the property of producing antimicrobial substances and are used in the fermentation and bio-preservation of food. The aim of this study was to evaluate the diversity of autochthonous lactic acid bacteria which belong to the useful or technological flora, of a sample of cow's milk from the region of Oued Rhiou. The physico-chemical analyzes of the milk allowed us to determine its quality (PH=6.62; Acidity Dornic D=19; Freezing point FP=0.523; Temperature T=28.6; Fat F=2, 89; Mineral matter C=5.58; Dry matter S=9.62; Protein P=2.95; Salt level S'=0.64; Lactose L=4.50). As for the microbiological study based on the isolation of lactic strains(12) from a certain number of phenotypic, physiological and biochemical characteristics (fermentation type, growth in the presence of NaCl: 4% and 6.5%; growth at pH=4.5 and pH 9.6; growth test at different temperatures 10°C, 37°C, 45°C; study of heat resistance; test of aesculin hydrolysis) and the use of the API gallery 50 CHL allowed us to identify the following 04 genera: Lactobacillus (42%), Lactococcus (25%), Enterococcus (25%) and Leuconostoc (8%).