Which Vibrio species is an obligate halophile (requires NaCl for growth)?

• A. Vibrio parahaemolyticus
• B. Vibrio vulnificus
• C. Vibrio cholerae
• D. Vibrio alginolyticus

Answer: (A)

Salt availability drives growth for many Vibrio species. An obligate halophile is an organism that must have a salt (NaCl) concentration to grow. Among these, Vibrio parahaemolyticus is the one that requires NaCl for growth. It is a marine-associated Vibrio commonly linked to seafood; in lab culture, growth is typically supported by NaCl-containing media, and growth can be poor or absent without salt. The other species listed do not require NaCl for growth under typical conditions: cholerae can grow in low-salt or even freshwater and is adaptable to a range of salt levels; vulnificus and alginolyticus tolerate saline environments but are not strictly dependent on NaCl. Therefore, the obligate halophile is Vibrio parahaemolyticus.