Survival of Vibrio cholerae 01 strains in shrimp subjected to freezing and boiling

Abstract

This research was undertaken to assess the resistance of Vibrio cholerae 01 strains inoculated into white shrimp, Penaeus schimitti, to heating and freezing treatments. Shrimp samples with and without carapace were obtained from Sao Luis, Brazil. Microbial analysis revealed the presence of marine vibrios including Vibrio alginolyticus, Vibrio parahaemolyticus, and other vibrios and aerobic gram-negative and gram-positive bacteria that grew on selective medium, thiosulfate-citrate-bile salt-sucrose agar. Samples with and without carapaces were heated before inoculating with cells of V. cholerae and then one-half of the samples was stored frozen at -200 degrees C and the other one-half was heated to boiling temperatures. Viable cells of the test organism were recovered from samples without carapaces, stored under frozen conditions, after 36 days. In contrast, no living cells were recovered after 26 days from samples with carapaces. Boiling temperatures were very damaging to V. cholerae 01 in shrimp samples with and without carapaces. Total destruction of the cells occurred within 1 to 2 min of exposure to heating.