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[Effect of polyene antibiotics on bacterial protoplasts]
Abstract:
The carbonyl-conjugated pentaenes flavofungin, nigrofungin and flavopentin exhibit considerable lytic activity toward Micrococcus lysodeikticus and Bacillus megaterium protoplasts. The antibiotics at concentrations of 5 to 14 microgram/ml cause lysis of 50% of the protoplasts within 15 min of their incubation. The antibiotics inhibit the activity of NADH oxidase and malate oxidase by 50% in the lysates of Micrococcus lysodeikticus and Bacillus megaterium protoplasts at concentrations of 30 to 50 microgram/ml; preincubation of the lysates with the antibiotics intensify the inhibiting action of the polyenes. Growth of the bacteria is inhibited when the minimal concentration of the polyenes is 75 to 100 microgram/ml. Interaction of the polyenes with bacterial membranes lacking sterols indicates that resistance of at least some bacteria to polyenes is caused by impermeability of the cell wall for these substances rather than by the absence of sterols in the membranes.
Insights
Carbonyl-conjugated pentaenes like flavofungin show potent lytic activity against bacterial protoplasts. Bacterial resistance to these polyene antibiotics may stem from cell wall impermeability, not absent membrane sterols.
Area of Science:
- Microbiology
- Biochemistry
- Antimicrobial Research
Context:
- Carbonyl-conjugated pentaenes are a class of antibiotics.
- These compounds, including flavofungin, nigrofungin, and flavopentin, possess significant biological activity.
- Their interaction with bacterial membranes is of interest due to potential antimicrobial mechanisms.
Purpose:
- To investigate the lytic activity of carbonyl-conjugated pentaenes against bacterial protoplasts.
- To determine the effect of these polyenes on bacterial membrane-associated enzymes like NADH oxidase and malate oxidase.
- To elucidate the mechanism of bacterial resistance to these antibiotics.
Summary:
- Flavofungin, nigrofungin, and flavopentin effectively lyse Micrococcus lysodeikticus and Bacillus megaterium protoplasts at low concentrations (5-14 µg/ml).
- These polyenes inhibit NADH oxidase and malate oxidase activity in bacterial lysates, with inhibition enhanced by preincubation.
- Bacterial growth inhibition occurs at higher concentrations (75-100 µg/ml).
Impact:
- Findings suggest bacterial cell wall impermeability, rather than the absence of sterols in membranes, is a key factor in resistance to these polyenes.
- This research provides insights into the antimicrobial mechanisms of polyene antibiotics.
- The study contributes to understanding bacterial membrane interactions and developing new antimicrobial strategies.