Seasonal characteristics and tetrodotoxin-producing ability of bacteria in gastropod Oliva hirasei

Abstract

Tetrodotoxin (TTX) is a well-known marine toxin, which is widely distributed in marine animals and originates from marine bacteria. To compare seasonal characteristics of aerobic bacteria in the toxic gastropod Oliva hirasei, the muscle and digestive gland of O. hirasei were collected from New Taipei City, and plated on ORI agar for aerobic plate count. Bacterial counts of the digestive gland were 7.10 and 8.89 log (CFU/g) from O. hirasei in August 2011 and March 2012, respectively, and those of the muscle were 6.84 and 8.20 log (CFU/g) in August 2011 and March 2012, respectively. The total bacterial counts in the March samples were higher than those in the August samples, but the amount of toxin showed an inverted pattern. The predominant genera from the muscle and digestive gland of O. hirasei were Vibrio, Pseudomonas, Shewanell, Pasteurella, Aeromonas, and others. Virio was 43 and 46% of the genera in August from the muscle and the digestive gland of O. hirasei and 70 and 82% in March. In addition, to detect the TTX-producing ability of isolated bacteria, the bacterial strains were cultured, extracted, and analyzed by HPLC and LC–MS/MS. The results showed that Vibrio, Pseudomonas, and Shewanella certainly produced TTX.