Depuration Capacity of Mussels (Mytilus galloprovincialis) in Presence of Marteilia Spp. Parasites

Bivalve molluscs are filter-feeding organisms present in the water column: during their activity, they could retain micro-organisms that are potentially dangerous to human health. For this reason, EU Regulations may require that a purification treatment be performed prior to bivalve trade. The length of the purification process could be affected by stress factors, such as parasitic infections. The purpose of this study was to determine if the presence of Marteilia spp. parasite in shellfish could modify time and efficacy of their microbiological purification treatment, in order to set up specific protocols. Lysosomal membrane stability, phagocytosis capacity, granulocyte/hyalinocyte rate and neutral lipid accumulation are biomarkers used to evaluate shellfish physiological state. These biomarkers were used to exclude any differences caused by stressor factors that could affect the purification results. Mussels were sampled from two different production areas. The presence or absence of parasites was confirmed by cytological test. Both groups of parasitized and non-parasitized mussels were contaminated with E.coli: they were then sampled for microbiological analyses and tested for biomarkers for up to 70 hours of purification. Parasitized and non-parasitized molluscs did not show any differences in levels of E. coli after 12, 24, 36, 48 and 70 hours of depuration. In relation to biomarkers, mussels seem to react to Lysosomal membrane stability in presence of Marteilia. The present study shows that the presence of Marteilia spp. does not affect the purification rate of mussels.