Q.20 Gas vacuoles are present in
- (A) Anabaena flos-aquae
- (B) Bacillus subtilis
- (C) Acanthurus nigrofuscus
- (D) Mycobacterium tuberculosis
Gas vacuoles are present in Anabaena flos-aquae, a cyanobacterium that uses these gas-filled structures for buoyancy regulation in aquatic environments. This SEO-optimized article answers the MCQ: Gas vacuoles are present in (A) Anabaena flos-aquae, (B) Bacillus subtilis, (C) Acanthurus nigrofuscus, (D) Mycobacterium tuberculosis—essential for microbiology and biotechnology students studying prokaryotic cytoplasmic inclusions.
Correct Answer: Option (A) Anabaena flos-aquae
Anabaena flos-aquae (now often classified as Aphanizomenon flos-aquae) contains gas vacuoles composed of gas vesicles—hollow, protein-bound cylindrical structures (75-100 nm diameter) that provide buoyancy.
These enable cyanobacteria to position optimally for photosynthesis near water surfaces during daylight and descend for nutrients at night. Gas vesicles collapse under turgor pressure (>2 atm) for depth control, regulated by GvpA/GvpC proteins.
Explanation of All Options
Gas vacuoles occur exclusively in certain prokaryotes, not eukaryotes or common soil bacteria:
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(A) Anabaena flos-aquae: Correct. Cyanobacterium with parallel gas vesicle bundles for flotation.
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(B) Bacillus subtilis: Incorrect. Gram-positive soil bacterium forms endospores, not gas vacuoles.
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(C) Acanthurus nigrofuscus: Incorrect. Marine surgeonfish (eukaryote)—no prokaryotic gas vacuoles.
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(D) Mycobacterium tuberculosis: Incorrect. Acid-fast pathogen with mycolic acids; no buoyancy structures.
Option Organism Type Gas Vacuoles? Key Feature (A) Anabaena flos-aquae Cyanobacterium Yes Buoyancy regulation (B) Bacillus subtilis Gram+ bacterium No Endospore formation (C) Acanthurus nigrofuscus Fish (eukaryote) No Marine vertebrate (D) Mycobacterium tuberculosis Acid-fast bacterium No Lung pathogen Biotechnology Relevance
Gas vacuole engineering creates microbial cell flotation for easy biomass harvesting in photobioreactors, linking to your fermentation kinetics (Q.12,15,16) and hairy root culture optimization (Q.11). Cyanobacteria like Anabaena produce biofuels and pharmaceuticals.
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