Abstract:

The dominant spoilage organisms in cultured Paralichthys olivaceus during cold storage at 4 ℃ were qualitatively and quantitatively investigated. Based on the colony morphology, biochemical and physiological characteristics, spoilage bacteria were isolated at the end of shelf life and identified using bacteria identification systems. Shewanella putrefaciens was dominated spoilage bacteria, which accounted for about 58.4% of all bacteria at the end of shelf life at 4 ℃. Pseudomonas which were common spoilage bacteria in aquatic products included Pseudomonas fluorescens, Pseudomonas taetrolens and Pseudomonas marginalis，with a corresponding proportion of 63.2%, 29.2% and 7.6%, respectively. Two types of egg yolk antibodies (IgY) against Shewanella putrefaciens, Pseudomonas fluorescens and Pseudomonas taetrolens were obtained by immunizing leghorn chicken by two methods, and their antibacterial efficiencies in liquid and solid media were evaluated. After incubation for 8 h in liquid culture, the inhibition ratio of the two IgYs at 100 mg/mL against antigen bacteria could attain between 61% and 78%, and after incubation for 24 h in solid culture, the inhibition ratio could reached between 27% and 40%. This demonstrates the potential application of egg yolk antibody as a natural antimicrobial agent for preservation and bacteria inhibition.

Key words: Paralichthys olivaceus, dominated spoilage organisms, Shewanella putrefaciens, Pseudomonas, Egg yolk immunoglobulin, antimicrobial activity