Answer to Question #92928 in Microbiology for ataniya singh

Question

With regard to the morphology, virulence factors and cultural characteristics, compare the
two species of vibrios with significant effect on humans.

Answer 1

Vibrio cholerae and Vibrio vulnificus are two representatives of vibrios that cause acute and dangerous food-borne infections. Both species are Gram-negative curved rods with a single polar flagellum.

V. cholerae is a facultative anaerobe. It produces pale-yellow, translucent colonies (2–3 mm) on a particular medium - thiosulfate citrate bile salts sucrose (TCBS) agar. The optimal conditions are 15–45 °C, pH 6–10, and NaCl concentration of 6%. Cholera toxin is an ADP-ribosylating enzyme and is the most crucial virulence factor of V. cholerae. Zonula occludin toxin and ace toxin are two other toxins produced by the species.

V.vulnificus is sensitive to the presence of iron as it produces hydroxamate, phenolate, and vulnibactin siderophores that scavenge iron ions. It is also halophilic and requires salt for growth. V. vulnificus is isolated using sodium dodecyl sulfatepolymyxin B-sucrose agar and Vibrio vulinficus agar. A capsular polysaccharide (CPS) is the most important virulence factor of V.vulnificus. It helps bacteria to avoid phagocytosis by macrophages. V.vulnificus also produces hemolysins, phospholipases, collagenase, and metalloprotease that cause host tissues destruction, apoptosis, and fluid loss associated with diarrhea.