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food safety, depuration, clams, V. parahaemolyticus, V. vulnificus


Vibrio spp are widely distributed in the marine environments and are responsible for common illnesses in many countries. The main objective of this study was to investigate the depuration capacity of Venus gallina artificially contaminated with Vibrio parahaemolyticus and Vibrio vulnificus. Contamination experiments were used to assess the accumulation capacity of clams in poorly, moderate and highly contaminated waters (Vibrio spp103/ml, 104/ml, 106/ml). All bivalves were exposed to contamination for 72 h and 8 experiments were performed. Accumulation capacity varied with respect to initial level. Comparing experiments dataset with two vibrios species, clams showed a different specific accumulation: in particular, molluscs evidenced a scarce accumulation capacity of V.vulnificus. Depuration trials were performed in close-circuit seawater-disinfection system that uses filtration, Ultra violet (UV) and ozone. Bivalves samples were collected every 12h until 3 days of depuration. Most of the depuration trials with V.parahaemolyticus showed a decrease in initial bacterial loads (4times lower values) after36-48 hours, but in subsequent periods, the trend remained stationary. In V. vulnificus tests, clams showed a scarce depuration capacity instead. Future studies are still required to assess the efficacy of the depuration process in reducing pathogenic Vibrio strain naturally accumulated in clams and to prevent significant economic losses to stakeholders due to long depuration periods.

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