Phenotypic characterization of Lactobacillus strains isolated from different biotopes

Abstract

Thirty three strains of Lactobacillus were isolated from human milk and infant faeces, animal (cow and goat) milks and from plants (Anagalis arvensis and Bromus mango species). The various strains were identified based on phenotypic tests. Amongst them, 12 strains belonged to group 1, which comprised L. acidophilus, L. helveticus and L. delbrueckii ssp. bulgaricus strains; 16 strains belonged to group 2, which comprised L. casei (ssp. casei and ssp. rhamnosus) and L. plantarum strains; and 5 strains
belonged to group 3, which comprised L. brevis and L. fermentum. The variance analysis (with onefixed criterion classification) of the potential for milk coagulation after 6 and 24 h of growth made possible the characterization of two homogeneous groups, fast and low acidifying strains. The human strains showed a resistance to acidic pH and to bile, indicating a tolerance to gastric acid. The probiotic potential was confirmed for one strain, owing to its antagonistic effect on Escherichia coli.