Caractérisation des bactéries lactiques du lait de chamelle

Abstract

Present study was carried out to investigate the physicochemical composition of camel milk. A wide variation was observed between three of milk collected from (M’sila). Fat, protein, lactose, solids not fat, and minerals contents ranged between: 3.43 and 5.36%, 3.44 and 3.92%, 4.99 and 5.69%, 9.27 and 10.55%, 0.28 and 0.32% respectively. While fpp, conductivity and pH ranged between - 0.59 and - 0.67°C, 11.05 and 12.61 mS.cm-1, 6.42 and 6.57. With the exception of minerals, the composition of milk is considered rich in comparison to that of bovine milk and those of most of camel milk described in the literature. To characterize the lactic microflora of camel milk, seven samples were collected aseptically from healthy females of three regions in south-eastern Algeria (M'sila, Biskra and l’Oued). The milk was inoculated in selective media (MRS and M17) for isolation of LAB.After phenotypic identification, the 48 isolates obtained were associated to four genera which are in order of dominance: Lactococcus (50%), Leuconostoc (31.25%), Lactobacillus (16.66%) and Enterococcus (2.08%). The presence of these genera in camel milk was also reported by other authors. The LAB were tested for their antagonism effect against five pathogenic bacteria (Staphylococcus aureus ATCC: 25923, Salmonella sp., Escherichia coli ATCC: 25922, Bacillus subtilis and Enterobacter cloacae) by the test of spot-on-the lawn. They inhibit all pathogenic strains and the best activity was obtained by lactobacilli strains. An isolate (O8) belonging to the genus showed the best inhibition against almost pathogenic bacteria. It was used to examine its probiotic potential in vitro. This strain showed resistance to acidity (pH: 2 and 3 after 3 hours of exposure) and to 0.3% of bile salts after 4h and 24h of incubation. To validate their use as a probiotic we must perform other tests in vitro and in vivo.