Putrescine, cadaverine, and indole production capabilities of bacteria isolated from wild domestic and aquacultured Ni-caraguan penaeid shrimp in progressive decomposition states were evaluated. The numbers and types of microorganisms responsible for the production of putrescine, cadaverine, and indole in wild and aquacultured shrimp increased with increasing decomposition temperature and time. Throughout the storage experiments, mean aerobic plate counts (log/g) ranged from 4.5 to 9.7 and 4.5 to 9.0 for domestic and Nicaraguan shrimp, respectively. Vibrio spp. were more prominent in Nicaraguan shrimp (Litopenaeus vannamei) than in domestic shrimp (Litopenaeus setiferus and Litopenaeus brasiliensis). The only amine-producing (putrescine) microorganism isolated from wild and aquacultured shrimp at all temperatures of decomposition (0, 12, 24, and 36°C) was Shewanella putrefaciens. On the basis of putrescine production by S. putrefaciens at 0 and 12°C and putrescine production by S. putrefaciens, Vibrio spp., and Morganella morganii at 24 and 36°C, putrescine should be considered a potential chemical indicator of decomposition in shrimp.
Ferric reductase is associated with the membranes of anaerobically grown Shewanella putrefaciens MR-1
