Q.57 Microorganisms that produce antibiotics are unaffected by the same antibiotic.
One of the mechanism to explain this is –
1. active pharmacophore of the bactericidal antibiotic, remains bound to antibodies while they are intracellular.
2. antibiotics are always produced in inactive forms, and get activated by the enzymatic action of the target cell.
3. microorganisms export the antibiotic, using efflux pumps, as soon as it exceeds a certain intracellular concentration.
4. antibiotics are made in parts, and are assembled after being transported to the extracellular environment.
Antibiotic-Producing Microbes: Efflux Pumps Mechanism
Microorganisms producing antibiotics remain unaffected by exporting them via efflux pumps when intracellular concentrations exceed thresholds, making option 3 correct.
Self-Resistance in Antibiotic Producers
Streptomycetes and other producers synthesize antibiotics like streptomycin but survive through multiple mechanisms including target modification, impermeability, and export.
Efflux pumps (e.g., RND family) actively extrude antibiotics using proton motive force, preventing toxic accumulation.
This intrinsic resistance enables industrial antibiotic production without autotoxicity.
Correct Answer: Option 3
Microorganisms export the antibiotic using efflux pumps as concentrations rise—pumps like SgmA in streptomycin producers maintain safe intracellular levels.
| Option | Mechanism | Validity |
|---|---|---|
| 1 | Active pharmacophore bound to antibodies intracellularly | False—no antibodies involved in prokaryotic resistance |
| 2 | Antibiotics produced inactive, activated by target cell enzymes | False—producers make active forms; inactivation protects producers differently |
| 3 | Export via efflux pumps above threshold | True—primary mechanism confirmed across Streptomyces |
| 4 | Assembled extracellularly from parts | False—biosynthesis occurs intracellularly on multimodular enzymes |
Option Explanations
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Option 1 (Incorrect): Antibodies irrelevant in bacterial self-protection; pharmacophores aren’t “bound” to evade toxicity.
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Option 2 (Incorrect): Producers synthesize active antibiotics; some zymogens exist but not universal mechanism.
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Option 3 (Correct): Efflux systems (MFS, MATE, RND) documented in tetracycline/streptomycin producers—export prevents self-harm.
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Option 4 (Incorrect): Non-ribosomal peptide synthetases/PKS complete assembly inside cells before export.
Efflux inhibitors are researched to combat clinical resistance, highlighting this mechanism’s clinical relevance beyond producers. Essential for NEET biotechnology syllabus.
