Vibrio cholerae O1 is uniquely identified by its 'string test' positivity. This test demonstrates which property of the organism?
- A Production of extracellular DNase
- B Flagellar motility enabling rapid spreading
- C Mucoid colony formation due to abundant extracellular polysaccharide ✓
- D Hemagglutination of chicken erythrocytes
Correct answer: C. Mucoid colony formation due to abundant extracellular polysaccharide
Explanation
The string test involves spreading a loopful of the bacterial colony on a slide with 0.5% sodium deoxycholate. V. cholerae O1 (both biotypes) forms a mucoid string when touched with a loop due to its copious capsular polysaccharide. It is a rapid presumptive identification test. Flagellar motility is demonstrated by darting motility in hanging drop preparation.
Reference: Ananthanarayan and Panicker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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