In Vitro Safety Evaluation of Novel Phyto Lactic Acid Bacteria Isolated from Fruits as Potential Probiotics

This study focused on the isolation of lactic acid bacteria (Probiotics) from non-dairy sources like fresh fruits including olive (Olea europea- Gamlik), mango (Magnifera indica L. cv. Chaunsa) and banana (Musa cavendish Basrai), which are available in local markets of Pakistan. The three novel strains of the enterococcus genus were isolated from these fruits. These species of enterococcus were molecularly identified with 16S rRNA gene sequencing. Enterococcus durans JCM8725 from olive, Enterococcus faecium MW 585366 from mango and Enterococcus faecium NBRC 100486 from banana were identified. These strains were positive for lipolytic and lactic acid production and negative for amylolytic, proteolytic, cellulolytic activities, DNase and hemolytic. E. durans JCM8725 demonstrated the highest survival rate viable cells count 7.58 Log CFU/mL at pH 2.0. Similarly, after four hours in 0.3% bile salt. E. durans JCM8725 had shown higher stability (7.88 Log CFU/mL). E. durans JCM8725 had shown elevated Cell Surface Hydrophobicity (CSH) at 51% and auto-aggregation at 44%. Due to these properties, E. durans JCM8725 had an inhibitory effect on pathogenic strains Escherichia coli ATCC25922, Pseudomonas. aeruginosa ATCC27853 and Staphylococcus aureus ATCC25923. Antibiotic susceptibility test (AST) against imipenem, vancomycin, penicillin, chloramphenicol and streptomycin revealed that E. durans JCM8725 exhibited antibiotic susceptibility over all antibiotics while other two strains were resistant to streptomycin. The E. durans JCM8725 had the highest DPPH scavenging activity, 42.5%. The strains were found safe. The hemolytic activity and the DNase test were negative in the in-vitro safety analysis