Contribution à l’étude des souches de bactéries lactiques isolées à partir du lait de chèvre

Abstract

This study focused on the isolation and characterization of lactic acid bacteria from raw goat milk collected in the Ain Témouchent region. The experimental work involved physicochemical analyses, including the measurement of pH and titratable acidity. Several microbiological analyses were also carried out to investigate the presence of total flora, coliforms, staphylococci, yeasts and molds, as well as lactic acid bacteria in goat milk samples. After isolation and purification, the obtained isolates were subjected to various identification tests, including Gram staining, catalase and oxidase tests, growth at different temperatures, pH levels, and NaCl concentrations, determination of the fermentative type, thermoresistance testing, and growth on Sherman milk-based medium. The antagonistic activity of the isolates against three pathogenic microorganisms was also evaluated, and an antibiotic susceptibility test was performed. The results revealed the presence of Gram-positive and catalase-negative lactic acid bacteria, showing good adaptation to various growth conditions and inhibitory activity against certain pathogenic microorganisms. This study therefore confirms the importance of raw goat milk as a source of lactic acid bacteria that can be exploited in the agri-food and biotechnological fields.