| Autor: |
Kortam YG; Department of Agricultural Microbiology, National Research Centre, Giza 12622, Egypt., Abd El-Rahim WM; Department of Agricultural Microbiology, National Research Centre, Giza 12622, Egypt., Khattab AEA; Department of Genetics and Cytology, National Research Centre, Cairo 12622, Egypt., Rebouh NY; Department of Environmental Management, Institute of Environmental Engineering, RUDN University, 6 Miklukho-Maklaya Street, 117198 Moscow, Russia., Gurina RR; Technosphere Security Department, RUDN University, 6 Miklukho-Maklaya Street, 117198 Moscow, Russia., Barakat OS; Department of Agricultural Microbiology, Faculty of Agriculture, Cairo University, Cairo 12613, Egypt., Zakaria M; Department of Agricultural Microbiology, Faculty of Agriculture, Cairo University, Cairo 12613, Egypt., Moawad H; Department of Agricultural Microbiology, National Research Centre, Giza 12622, Egypt. |
| Abstrakt: |
Antibiotic-resistant bacteria represent a serious public health threat. For that reason, the development of new and effective antibiotics to control pathogens has become necessary. The current study aims to search for new microorganisms expressing antibiotic production capacity. Fifteen sites covering a wide range of harsh environmental conditions in Egypt were investigated. Two hundred and eighty bacterial isolates were obtained and then tested against pathogenic bacteria using the agar disk diffusion technique. Fifty-two (18.6% of the total) of the isolates exhibited antagonistic properties, which affected one or more of the tested pathogens. The isolate 113 was identified as Bacillus licheniformis and isolate 10 was identified as Brevibacillus borstelensis using the 16S rRNA technique. The B. licheniformis strain was stronger in antibiotic production against S. typhi, M. luteus , and P. ariginosa, whereas the strain Br. borstelensis was more efficient against B. cereus, E. coli, and Klebs. sp. The sensitivity of the strains to commercial antibiotics showed that B. licheniformis was highly sensitive to seven commercial antibiotics, whereas Br. borstelensis was sensitive to nine antibiotics. The two strains were subjected to ethyl methanesulfonate (EMS) mutagenesis to obtain mutants with a higher antibiotic production. The total bacterial count was measured after treatment with EMS mutagen and showed a significant gradual increase in the antimicrobial activity, which was achieved via shaking in the presence of EMS for 60 min. High antimicrobial activities were noted with 17 and 14 mutants from the B. licheniformis and Br. borstelensis strains, respectively. The mutant B. licheniformis (M15/Amo) was more active than the parent strain against S. aureus (212.5%), while the mutant Br. borstelensis (B7/Neo) was more effective against S. typhi (83.3%). The present study demonstrates the possibility of obtaining potent antibiotic-producing bacteria in hot spring waters and further improving the indigenous bacterial capacity to produce antibiotics by using EMS mutagenesis. |
