Accumulation and Depuration of Pathogenic and Indicator Microorganisms by the bivalve mollusc, Chamelea gallina L, Under Controlled Laboratory Conditions

Abstract

The comparative accumulation and depuration processes for several microorganisms (Escherichia coli, Salmonella typhimurium, Vibrio parahaemolyticus, Aeromonas hydrophila, Streptococcus faecalis, Staphylococcus aureus, and MS-2 coliphage) by the striped venus, Chamelea gallina, under controlled laboratory conditions were studied. Microorganisms accumulated rapidly in bivalves during the first 6 h, with accumulation rates between 3.2 to 360.5 organisms/h depending on the type of microorganism. The relative patterns and rates of elimination of the microorganisms suggest that they are eliminated from shellfish in two different ways. One is of a mechanical nature that results in microbial elimination during the first 12 h. The other elimination mechanism depends upon the microbial species and their accumulated number. All microorganisms tested were eliminated completely by the molluscs after 3 d of depuration, except MS-2 bacteriophages. Results indicate that MS-2 coliphages may be a more reliable indicator of the microbial depuration efficiency by the shellfish under laboratory conditions than E. coli.