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Molluscan shellfish can cause food borne diseases and here we investigated if addition of Vibrio -antagonising bacteria could reduce Vibrio vulnificus in model oyster systems and prevent its establishment in live animals. Phaeobacter inhibens , which produces an antibacterial compound, tropodithietic acid (TDA), inhibited V. vulnificus as did pure TDA (MIC of 1–3.9 μM). P. inhibens DSM 17395 (at 10 6 cfu/ml) eradicated 10 5 cfu/ml V. vulnificus CMCP6 (a rifampicin resistant variant) from a co-culture oyster model system (oyster juice) whereas the pathogen grew to 10 7 cfu/ml when co-cultured with a TDA negative Phaeobacter mutant. P. inhibens grew well in oyster juice to 10 8 CFU/ml and sterile filtered samples from these cultures were inhibitory to Vibrio spp. P. inhibens established itself in live European flat oysters ( Ostrea edulis ) and remained at 10 5 cfu/g for five days. However, the presence of P. inhibens could not prevent subsequently added V. vulnificus from entering the live animals, likely because of too low levels of the biocontrol strain. Whilst the oyster model studies provided indication that P. inhibens DSM 17395 could be a good candidate as biocontrol agent against V. vulnificus further optimization is need in the actual animal rearing situation. [ABSTRACT FROM AUTHOR]

This study was focused on the evaluation of the microbiological indices, defined by European legislation, before and after the depuration of clams ( Chamelea gallina) landed in category B seawater. The survival of depurated clams and the meat yield were also evaluated. The results obtained from October 2002 to September 2003 evidenced a mean microbial reduction during depuration of 62% for Escherichia coli and 54% for fecal coliforms (FC). All the samples had FC counts below the limit after 24 h depuration with the exception of the August samples. E. coli was found in concentration slightly higher than the legal limit only in the samples of December and January. In August, the E. coli concentration did not decrease during the depuration, while in the other samples significant reduction of E. coli concentration was observed. Salmonella spp. and V. parahaemolyticus were never detected in the clams harvested between March and September. Vibrio alginolyticus was found in the clams harvested in May and September both before and after the depuration process. The viability of clam was not negatively affected by depuration, in fact, an increase of viability was observed with the exception of the samples of April. The meat yield was not influenced by the depurative treatment in C. gallina; the mean value found before depuration, 10.47% (with 1.95 SD), did not significantly vary after the treatment (10.58%, SD 2.07). In conclusion, the depuration conditions can improve the quality of C. gallina; however, its effects on microbiological quality depended on environmental conditions. [ABSTRACT FROM AUTHOR]