CHARACTERIZATION, IN-VITRO EVALUATION OF PROBIOTIC POTENTIAL AND ANTAGONISTIC ACTIVITY OF SELECTED LACTIC ACID BACTERIA STRAINS ISOLATED FROM NATURAL ORIGIN AGAINST SOME HUMAN PATHOGENS | ||||
| Bulletin of Pharmaceutical Sciences Assiut University | ||||
| Article 22, Volume 44, Issue 1, June 2021, Page 225-241 PDF (1.72 MB) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/bfsa.2021.174149 | ||||
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| Authors | ||||
Azza S. Zakaria ; Mervat A. Kassem; Mona S. El Far; Eva A. Edward
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| Department of Microbiology and Immunology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt | ||||
| Abstract | ||||
| Probiotic bacteria have recently become popular for their health-related beneficial effects. In this study, 19 lactic acid bacteria were isolated from breast milk, dairy products, infant stool, vaginal swabs, fermented beverages, and fermented grapes. These isolates were evaluated for their tolerance to gastrointestinal conditions, hydrophobicity, auto-aggregation, and antimicrobial activity. Five isolates, belonging to Pediococcus spp. and Lactobacillus spp., showed potential probiotic features. These isolates were tested for the presence of virulence enzymes and for susceptibility to various antibiotics. The isolates were found to be non-hemolytic and lacked gelatinase and deoxyribonuclease enzymes, however, some antibiotic resistance genes were detected. To ensure the safety of the used probiotics, cell-free supernatants (CFS) of the promising candidates were prepared and its antimicrobial activity before and after neutralization was assessed against standard strains of Candida albicans, Gram-positive, and Gram-negative bacteria. The neutralization of the CFS significantly diminished the antibacterial and antifungal activities of probiotics. Using the time-kill assay, the combination of CFS of Lactiplantibacillus plantarum with gentamicin and ceftazidime was tested against Staphylococcus aureus and Escherichia coli clinical isolates. A significant reduction in log number of survivors was obtained with gentamicin against E. coli and with ceftazidime against both isolates. The anti-biofilm ability of the CFS of the selected probiotics was tested as well. Neutralized CFS caused 26-52% inhibition of S. aureus isolate biofilm formation compared to the control. In conclusion, the five selected isolates could be considered promising probiotic candidates that can be used as biotherapeutics in case of bacterial infection. | ||||
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