Bacteriophage Cocktail Effectively Prolonging the Shelf-Life of Chilled Fish.

We developed a technological accessory bacteriophage-based preparation and a method for phage-mediated bioprocessing for elimination of pathogenic microorganisms from the surface of fresh fish and for prolongation of the shelf-life of chilled hydrobionts. Specimens of rainbow trout (Salmo irideus) served as the objects of the study carried out at a fish-processing plant in the Republic of Karelia. The specimens were decontaminated by a bacteriophage cocktail containing six original virulent phage strains characterized by their pheno- and genotypical properties. A new method of biodecontamination (plunging the rainbow trout for 30 sec into a solution of bacteriophage cocktail (bacteriophage titers ≥108 PFU/ml) delayed bacterial degradation of hydrobionts by 3 days. The use of the new method for decontamination of food half-products - phage-mediated bioprocessing - promoted preservation of the initial ecological purity, nutritive value, and taste of the products and prolonged their shelf-life in comparison with the actual standards.

Identification of Infectious Salmon Anaemia Virus from Imported Iced Atlantic Salmons.

Infectious Salmon anaemia virus (ISAV) has become a threat to the salmon industry worldwide and has caused considerable economic loss. In the present study, 9 suspect cases of ISAV infection were identified from iced Atlantic salmons imported from Norway in 2014 through Shenzhen port (Shenzhen, China) using methods recommended by the World Organization for Animal Health. However, the results of virus isolation were negative., Based on the sequence analysis of ISAV segment 6, the 9 ISAV isolates belonged to the HPRO type, had high homology (98.3%~100.0%) and closest relationship with Norway strains. We identified the 9 positive HPRO ISAVs from 491 iced Atlantic salmons (1. 8%). Therefore, we should strengthen the quarantine of iced Atlantic salmons from Norway in case of HPRO ISAV into China.

Detection of noroviruses in shellfish and semiprocessed fishery products from a Belgian seafood company.

Shellfish have been implicated in norovirus (NoV) infection outbreaks worldwide. This study presents data obtained from various batches of shellfish and fishery products from a Belgian seafood company over a 6-month period. For the intact shellfish (oysters, mussels, and clams), 21 of 65 samples from 12 of 34 batches were positive for NoVs; 9 samples contained quantitative NoV levels at 3,300 to 14,300 genomic copies per g. For the semiprocessed fishery products (scallops and common sole rolls with scallop fragments), 29 of 36 samples from all eight batches were positive for NoVs; 17 samples contained quantitative NoV levels at 200 to 1,800 copies per g. This convenience study demonstrated the performance and robustness of the reverse transcription quantitative PCR detection and interpretation method and the added value of NoV testing in the framework of periodic control of seafood products bought internationally and distributed by a Belgian seafood processing company to Belgian food markets.

Infectious pancreatic necrosis virus in fish by-products is inactivated with inorganic acid (pH 1) and base (pH 12).

The aquaculture industry needs a simple, inexpensive and safe method for the treatment of fish waste without heat. Microbial inactivation by inorganic acid (HCl) or base (KOH) was determined using infectious pancreatic necrosis virus (IPNV) as a model organism for fish pathogens. Salmonella and spores of Clostridium perfringens were general hygiene indicators in supplementary examinations. IPNV, which is considered to be among the most chemical- and heat-resistant fish pathogens, was reduced by more than 3 log in 4 h at pH 1.0 and pH 12.0. Salmonella was rapidly inactivated by the same treatment, whereas spores of C. perfringens were hardly affected. The results indicate that low and high pH treatment could be particularly suitable for fish waste destined for biogas production. pH treatment at aquaculture production sites could reduce the spread of fish pathogens during storage and transportation without disturbing the anaerobic digestion process. The treatment could also be an alternative to the current energy-intensive steam pressure sterilization of fish waste to be used by the bioenergy, fertilizer and soil improver industries.

Noroviruses in seafood: a 9-year monitoring in Italy.

Norovirus (NoV) are increasingly important as etiological agents of gastrointestinal infections. Consumption of bivalve molluscs and ready-to-eat fishery products is one of the most common ways of acquiring NoV foodborne infections, and the rise of outbreaks of viral gastroenteritis represents an important health problem that is also responsible for economic losses. The aim of this work was to define the prevalence of NoV contamination in preserved fishery products and in shellfish commercialized in Italy, taking into account the results obtained during 9 years of survey (2003-2011) and paying special attention to the regions more involved in national production. A total of 4463 samples were examined (2310 mussels, 1517 clams, 510 oysters, 22 other shellfish species, 104 preserved seafood products) and the average positivity rate for NoV presence was 4.1% and ranged from 0.6% in 2007 to 9.8% in 2003 and from 1.9% in preserved seafood products to 4.7% in mussels. Genetic characterization of circulating strains showed a prevalence of genogroup II genotypes, including GII.b and GII.e polymerase types and different GII.4 variants. This information could contribute to the optimization of risk-based sampling strategies for NoV contamination in seafood, taking into account variability in different species and from year to year.

Thermal inactivation of infectious pancreatic necrosis virus in a peptone-salt medium mimicking the water-soluble phase of hydrolyzed fish by-products.

Infectious pancreatic necrosis virus (IPNV) (serotype Sp) was exposed to temperatures between 60 and 90°C in a medium mimicking the water-soluble phase of hydrolyzed fish by-products. D values ranged from 290 to 0.5 min, and the z value was approximately 9.8°C. Addition of formic acid to create a pH 4 medium did not enhance heat inactivation. Predicted inactivation effects at different temperature-time combinations are provided.

Contamination of fish products: risks and prevention.

The risks of contamination of finfish products with active pathogens largely depend on the type of product concerned and disposal methods of the importing country. Frozen fish used as bait or to feed high-value species present the greatest risk as vehicles of contamination because they are unprocessed. Freezing preserves viral- and some bacterial-pathogens, thus the use of such fish as bait can introduce those pathogens into natural waters. Conversely, processed fish, particularly fillets, which have been heat-treated or cooked, present the lowest risk. If fish are processed after importation, care must be taken to ensure effective waste disposal, with particular attention to the prevention of scavenging by avian vectors and drainage from landfills into natural waters. Liquid waste should be disinfected and disposed of well away from natural waters.