Phenotypic and Molecular Characterization of Lactobacilli Isolated from breast-fed Infants faeces in Bechar region,South West of Algeria

Abstract

Lactobacilli are of great importance to humans, as they are essential members of a healthy human microbiota at various niches and serve as biologically and functionally important components of a healthy human diet. For this reason, the isolation of lactobacilli strains from infant feces (less than 6 months old) was carried out in Bechar region, Algeria. In total, 62 strains were isolated, purified, and identified based on the physiological and biochemical methods. For final confirmation, API 50 CHL gallery was used. The iden ca on and phylogenetic analysis of isolated strains was performed by sequencing the 16S rRNA gene, which led us to identify four species with different percentages; Lactobacillus rhamnosus, L. fermentum, L.mucosa, L. plantarum. With regard to the characteristics of technological interest, most of the identified strains exhibited good lactic acid production. However, it was not until after 3 hours of incubation at 37 °C that isolated lactobacilli produced a maximum acidity, which reached Δ pH 0.54 in the reconstituted milk. The results were different with camel milk, in the first time, and this was observed in the acidity rate which was generally lower in this type of milk in which acidity reached Δ pH 0.47 .As regards the proteolytic power, the strains showed a high level of proteolysis. Regarding the lipolytic activity, it was observed that none of the lactobacilli tested expressed lipolytic activity in the presence of buffer and olive oil, whereas the results of the strains were different as regards the flavoring activity and the texturing activity.