abstract
As bivalve molluscs are filter feeder, often consumed raw or lightly cooked and are frequently cultivated in contaminated waters, they are implicated in food-borne disease transmission to human. The present study investigated the potential application of bacteriophage (or phage) phSE-2, phage phSE-5 and phage cocktail phSE-2/phSE-5 to decrease the concentration of Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) during the depuration of natural and artificially contaminated cockles (Cerastoderma edule). Cockles were artificially infected with 10(5) and 10(6) colony-forming units (CFU)/mL of S. Typhimurium in static seawater and infected group were treated with phages at four different MOI values: 0.1, 1, 10 and 100. Depuration in static seawater at multiplicity of infection (MOI) of 0.1 with single phage suspensions of phSE-2 and phSE-5 provided the best results, as it decreased by similar to 1.3 and 1.7 log CFU/g, respectively, the concentration of Salmonella spp. after a 4 h treatment. At a MOI of 0.1, the rate of inactivation with single phage suspensions was higher when compared with the results obtained using the phage cocktail. However, in naturally contaminated cockles treated in static seawater with single phage suspensions and phage cocktail phSE-2/phSE-5, similar decreases in cultivable bacteria concentration (similar to 0.7-0.9 log CFU/g) were achieved after 6 h of treatment. When artificially contaminated cockles were depurated with phage phSE-5 in a recirculated seawater system (mimicking industrial depuration conditions), a 0.9 and 2.0 log CFU/g reduction of Salmonella spp. was reached after 4 and 6 h treatment. Once the depuration process was performed without phage, a 6 h treatment was needed to obtain a 1.1 log CFU/g reduction of Salmonella spp. Results indicated that combining phage biocontrol with depuration procedures enhance bivalve microbial safety for human consumption by improving decontamination efficiency, proving that this technology can be transposed to the bivalves industry. Moreover, this approach also displays the advantage of reducing the time required for depuration and consequently its associated costs. (C) 2016 Elsevier Ltd. All rights reserved.
keywords
PHAGE THERAPY; VIBRIO-PARAHAEMOLYTICUS; BIVALVE SHELLFISH; ESCHERICHIA-COLI; IN-VITRO; LYTIC BACTERIOPHAGES; FOODBORNE PATHOGENS; UNITED-STATES; CHICKEN SKIN; INACTIVATION
subject category
Food Science & Technology
authors
Pereira, C; Moreirinha, C; Rocha, RJM; Calado, R; Romalde, JL; Nunes, ML; Almeida, A
our authors
acknowledgements
This work was supported by FEDER through COMPETE - Programa Operational Factores de Competitividade, and by National funding through Fundacao para a Ciencia e Tecnologia (FCT), within the research projects FCOMP-01-0124-FEDER-013934 and PROMAR 31-03-05-FEP-0028. Thanks are also to Centre for Environmental and Marine Studies (project Pest-C/MAR/LA0017/2013), and to Department of Biology of University of Aveiro. Financial supports to Pereira C. in form of a PhD grant (SFRH/BD/76414/2011), Moreirinha C. in form of a Postdoctoral grant (ENV/ES/001048) and Rocha R. J. M. in form of Postdoctoral grant (SFRH/BPD/99819/2014).