Isolement et caractérisation de bactéries lactiques àpartir de yaourt commercialisé de la région de AinTémouchent

Abstract

Lactic acid bacteria play an essential role in the fermentation and bio-preservation of food. In addition to their technological interest, they have also always shown beneficial effects on the balance of the intestinal flora and human health. This study aimed to assess the viability of lactic acid bacteria in yogurt containing Bifidobacterium. For this purpose, 17 samples of yogurt marketed in the city of Ain Témouchent, were analyzed. The isolation of lactic acid bacteria was sought on three media M17, MRS and Esty. The count results showed the presence of lactic acid bacteria in all the samples analyzed. A total of 24 isolates were obtained and then identified by conventional tests against 6 sugars plus indole and esculin. The identification results showed 4 genera of lactic acid bacteria: Streptococcus sp. (47.06%), Lactococcus sp. (41.18%), Enterococcus sp (17.65) and Lactobaccillus (5.88%). As for the identification 1PI 50CHL of bacteria isolated under Bifidobacterium isolation conditions, the isolates were proven to belong to Lactobacillus delbrukii sbsp delbrukiii, a second species to Lactococcus lactis and a third to Streptococcus thermophilus. In the end, the results of thisresearch show the viability of lactic acid bacteria in yogurt but do not negate the presence of Bifidobacterium.