Benaissa Atika^1,, Babelhadj Baaissa^{1, 2}, Mimouni Yamina³, Touhami Imene¹

Meat is a nutrient-dense food. This makes it a favorable environment for the proliferation of the most bacteria even if this food is refrigerated. The objective of this study was to follow the evolution of psychrotrophic bacteria mainly of the genus "Pseudomonas" on meat beef from the slaughterhouse of the municipality of Ouargla, during refrigeration. Samples were taken aseptically from the thighs of 15 bovine carcasses using the excision method. The psychrotrophic flora was counted on the nutrient agar and Plate Count Agar media, by mass inoculation of these culture media with the stock solution and its decimal dilutions. The phenotypic identification of the strains after isolation and purification was carried out by a morphological characterization of the colonies, microscopic of the bacterial cells and then the latter were subjected to a set of biochemical tests. The isolation of Pseudomonas was done on the two selective media: King A and King B (King A and King B media are used to guide the identification of Pseudomonas (the detection of the synthesis of pyocyanin and pyoverdin), the purification of the strains cultivated on these media was carried out on the nutrient broth then Nutrient Agar medium (GN) and the identification was accomplished by different biochemical tests. The count revealed the presence of psychrotrophic flora in all the meat samples analyzed. The means of contamination by this flora were 4.22±0.29 logufc/g on GN medium and 4.08±0.49 logufc/g on PCA medium. The isolated and purified strains belonged to ten strains, eight of which belonged to the genus: Pseudomonas, and two presented characteristics other than this genus. The bacterial diversity of this meat in the chilled state revealed six bacterial genera: Pseudomonas, Micrococcus, Acinetobacter, Flavobacterium, Staphylococcus and Proteus. This leads to the conclusion that the meat beef produced at the slaughterhouse of Ouargla and preserved by refrigeration contains a bacterial flora belonging to several genera of psychrotrophic bacteria.

contamination, conservation, meat, spoilage flora, pseudomonas