Isolement et identification de la flore lactique totales à partir de lait cru de vache

Abstract

Lactic acid bacteria have gained great importance by their presence in the agro-food industry for a long time. They provide special characteristics such as aroma, texture and food safety thanks to the organic acids produced that lower the pH in the medium. In this framework, our study was carried out on 03 samples of raw milk from treated cow coming from the farm of Hassi mamèche wilaya of Mostaganem, after isolation and purification; 10 strains are found to belong to the group of lactic bacteria. Phenotypic identification; Biochemical and physiological studies (fermentation type, growth in the presence of NaCl: 6.5%, growth at pH 9 also the growth tests of the different temperatures: 4 ° C., 37 ° C. and 42 ° C., Growth test in sharman milk, DHA test, acetine production, esculin test and, at the end, fermentation of sugars in order to identify and classify these strains at the level of their genus And species. The identification results obtained allowed us to identify: 50% Lactobacillus with 5 species of the genus: Lactobacillus plantarum, Lactobacillus casei Lactobacillus fermentum, Lactobacillus rhamnosus, Lactobacillus acidophilus. With a percentage of 20% Two subspecies of the genus Lactococus lactis subsp. Lacti, and Lactococcus lactis ssp diacetylactis. For Enterococcus it was possible to identify as a species of the genus Enterococcus faecium with a percentage of 10% and as sub-species of genus Leuconostoc mesenteroides subsp. Mesenteroides 10% and 10% of Pediococcus halophilus