The first study of probiotic properties and biological activities of lactic acid bacteria isolated from Bat guano from Er-rachidia, Morocco

Abstract

This research aimed to investigate the in vitro properties of lactic acid bacteria (LAB) isolated from bat guano (fresh and decomposed). From the 20 isolated bacteria we have screened the catalase-negative ones. Seven LAB were screened, identified through 16S rDNA sequencing and tested for their probiotic potential based on their tolerance to bile salts (0.3%) and simulated gastric juice, their adhesion properties through hydrophobicity, auto-aggregation and co-aggregation with food-borne bacteria, their safety (haemolytic, gelatinase activity, and antibiotic susceptibility), their antibacterial activity against three food-borne bacteria, Listeria monocytogenes ATCC 19115, Staphylococcus aureus ATCC 114 and Escherichia coli ATCC 8539. They were also tested for their β-galactosidase activity and for their antioxidant property. Only five bacteria showed an antibacterial and β-galactosidase activity (Enterococcus mundtii MAV6B, Enterococcus faecium V6-112, Enterococcus gallinarum HBUAS52471, Enterococcus casseflavus APHG2, and Bacillus wehenstephensis B31). All the strains were able to resist the different gastrointestinal conditions and showed a high antioxidant property. The results were used as an input for Principal Component Analysis (PCA) and showed that E. gallinarum HBUAS52471, E. mundtii MAV6B, E. faecium V6-112, and B. wehenstephensis B31 are the most promising probiotic in this study.