Safety and Functional Aspects of Selected Probiotic Lactobacilli Strains from Water of Cassava’s Fermentation

Many Lactobacilli isolated from foods present probiotic properties, but some of them have been linked to possible clinical cases. Therefore, it is necessary to verify their safety before probiotic use. Our previous works have demonstrated acid and bile tolerances of Lactobacilli strains from the water of cassava's fermentation, without regard to the molecular basis of these resistances or the safety and adhesive aspects of the isolates. This study aimed to investigate the genotypic basis of acid and bile tolerance, safety and adhesion properties of eight probiotic Lactobacilli. The functional properties of their bile salt hydrolases were also studied. All strains were screened for gtf (acid and bile tolerance), clpL (acid and bile tolerance) and hdc (biogenic amine production) genes and investigated for hydrophobicity, co-aggregation and auto-aggregation. Moreover, hemolytic and gelatinase abilities, as well as antibiotic susceptibility, were examined for safety properties assessment. The eight selected strains were found to possess the clpL gene in their genome. They also showed excellent cell surface characteristics testifying their good adhesion and colonisation abilities. On the other hand, they were free from virulence factors (hemolytic and gelatinase activities), do not showed antibiotic resistance, and do not possess the hdc gene, a confirmation of their safe character for probiotic applications. The most promising probiotic candidates based on Principal Component Analysis were L. paracasei 62L (accession number: KU886178), L. Plantarum 84L (KU886185) and 86L (KU886187) with good auto and co-aggregation properties. The study of the predicted structure of L. Plantarum 86L bile salt hydrolase revealed that it has a structural similarity with previously identified bile salt hydrolases which substrate preference is glyco-conjugated bile. The Lactobacilli from the water of cassava's fermentation have exciting cell surface characteristics and are safe for probiotic applications.