Application of chitosan microparticles for reduction of vibrio species in seawater and live oysters (Crassostrea virginica).
Human Vibrio infections associated with consumption of raw shellfish greatly impact the seafood industry. Vibrio cholerae-related disease is occasionally attributed to seafood, but V. vulnificus and V. parahaemolyticus are the primary targets of postharvest processing (PHP) efforts in the United States, as they pose the greatest threat to the industry. Most successful PHP treatments for Vibrio reduction also kill the molluscs and are not suitable for the lucrative half-shell market, while nonlethal practices are generally less effective. Therefore, novel intervention strategies for Vibrio reduction are needed for live oyster products. Chitosan is a bioactive derivative of chitin that is generally recognized as safe as a food additive by the FDA, and chitosan microparticles (CMs) were investigated in the present study as a potential PHP treatment for live oyster applications. Treatment of broth cultures with 0.5% (wt/vol) CMs resulted in growth cessation of V. cholerae, V. vulnificus, and V. parahaemolyticus, reducing culturable levels to nondetectable amounts after 3 h in three independent experiments. Furthermore, a similar treatment in artificial seawater at 4, 25, and 37°C reduced V. vulnificus levels by ca. 7 log CFU/ml after 24 h of exposure, but 48 h of exposure and elevated temperature were required to achieve similar results for V. parahaemolyticus and V. cholerae. Live oysters that either were artificially inoculated or contained natural populations of V. vulnificus and V. parahaemolyticus showed significant and consistent reductions following CM treatment (5%) compared to the amounts in the untreated controls. Thus, the results strongly support the promising potential for the application of CMs as a PHP treatment to reduce Vibrio spp. in intact live oysters.
Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, USA.
Lei
L
Fang
Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, USA.
Bernhard
B
Wolmarans
Department of Animal Sciences and Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA.
Minyoung
M
Kang
Department of Animal Sciences and Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA.
Kwang C
KC
Jeong
Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida, USA acw@ufl.edu.
Anita C
AC
Wright
D000818:Animals; D000890:Anti-Infective Agents / Q000378:metabolism*; D048271:Chitosan / Q000378:metabolism*; D015169:Colony Count, Microbial; D049896:Crassostrea / Q000382:microbiology*; D005516:Food Microbiology / Q000379:methods; D012623:Seawater / Q000382:microbiology*; D013696:Temperature; D013997:Time Factors; D014481:United States; D014734:Vibrio cholerae / Q000187:drug effects* / Q000302:isolation & purification; D014736:Vibrio parahaemolyticus / Q000187:drug effects* / Q000302:isolation & purification; D041261:Vibrio vulnificus / Q000187:drug effects* / Q000302:isolation & purification
D000890:Anti-Infective Agents; D048271:Chitosan