Triggering of the antibacterial activity of Bacillus subtilis B38 strain against methicillin-resistant Staphylococcus aureus.
When cultured in minimal growth medium, the B38 strain of Bacillus subtilis did not exhibit any antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) clinical isolate. Coculturing B38 strain with viable MRSA cells weakly increased antibacterial activity production (20 AU/ml). Addition of dead MRSA cells in a B38 culture, increased by 8-fold the B. subtilis strain antibacterial activity reaching 160 AU/ml against MRSA strain. This antibacterial activity recovered from cell-free supernatants was stimulated by an autoinducing compound which is sensitive to the action of proteinase K suggesting a proteinaceous nature. This compound was heat-stable till 80 °C and showed a molecular mass around 20 kDa as determined by SDS-PAGE. These results suggest that the production of antibacterial compounds by B38 strain is dependent on the amount of the autoinducing compound.
Laboratoire des Substances Bioactives, Centre de Biotechnologie de Borj-Cedria, BP-901, Hammam-lif Cedex, Tunisia.
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D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D000898:Antibiosis; D001412:Bacillus subtilis / Q000737:chemistry / Q000378:metabolism* / Q000472:pathogenicity; D001426:Bacterial Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D018920:Coculture Techniques; D003470:Culture Media / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D006358:Hot Temperature; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000254:growth & development; D008826:Microbial Sensitivity Tests
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D003470:Culture Media