Microbiological characterization of a rearing system for the common sea urchin Paracentrotus lividus: a support to technical production regulations redaction and system monitoring

Objective: The overexploitation of the sea urchin Paracentrotus lividus stock, as a consequence of the growing market demand for roe, has boosted the research for echinoderm rearing. The chemical, physical, and microbiological characteristics of land-based facilities are crucial for sea urchins' health and human consumption of their products. In Italy, health-hygienic regulations for P. lividus rearing are still to be perfected by the authorities. In this context, we characterized the microbiological quality of a pilot land-based facility for sea urchin production at the University of Cagliari (Italy) to support the development of technical production regulations.Materials and Methods The accredited Hygiene Laboratory of Cagliari University collected and analyzed the samples in June 2023. Mesophilic bacteria, yeasts, and molds were searched for in air and on surfaces. Total coliforms and Escherichia coli, Enterococci, Pseudomonadaceae, Staphylococcus aureus, sulfite-reducing Clostridia, and Vibrio spp. were identified in water samples. We searched forVibrio spp. and Pseudomonas spp. in the gonads and coelomic fluid of sea urchins.Results Although air, surfaces, and water quality were satisfactory overall, some critical points should be monitored more strictly. Enterococci concentration was 250 CFU/100 mL in the water reserve, suggesting animal contamination (other than humans). Pseudomonas aeruginosa was the most resistant to filtration processes, with a residual concentration of 6 CFU/250 mL after the second filtration. No colonies of Vibrio spp. or Pseudomonas spp. were isolated in sea urchins' gonads or coelomic fluid.Conclusions Starting from the results, we provided targeted advice for developing technical production regulations, system monitoring, and facility routine maintenance in accordance with the 'best practice' approach. This analysis could be considered a first step toward the elaboration of common regulations about the minimal standards for the breeding environment of P. lividus by national and regional authorities.