Identification and Screening of Bacteriocin-producing Lactobacillus plantarum and Its Effects on Preservation of Large Yellow Croaker

In this study, the screening of lactic acid bacteria from traditional fermented food was carried out by enrichment culture, dilution separation, and agar plate diffusion experiments. Physiological and biochemical and 16S rDNA gene sequence homology analysis were used to identify the lactic acid bacteria. Then, the main antibacterial substances produced by the lactic acid bacteria were determined by acid excretion, hydrogen peroxide exclusion, and protease hydrolysis. Finally, the bacteriocin crude extract was obtained by alcohol precipitation and Sephadex LH-20 chromatography, and then was applied to the preserving the whole large yellow croaker. To evaluate the preservation effect of the bacteriocin crude extract on the large yellow croaker, sensory evaluation, pH determination, viable cell counts, TVB-N determination and texture profile analysis were systematically carried out every 3 days. The experimental results showed that the lactic acid bacteria isolated from shrimp paste was Lactobacillus plantarum and named MMB-11. Meanwhile, the bacteriocin produced by MMB-11 was sensitive to protease and had notable acid tolerance and thermal stability. With the application of the bacteriocin on the preservation of large yellow croaker, the viable cell counts in MMB-11 group, control group and Nisin-treated group after 12 d of storage were 3.50×10⁴, 1.10×10⁵ and 4.50×10⁴ CFU/g, respectively. Furthermore, after 12 d of storage, the TVB-N treated with MMB-11 group, control group and Nisin group were 20.91±0.66、31.37±0.21 and 21.44±0.45 mg/100 g, respectively. Overall, the results showed that the crude bacteriocin extract of MMB-11 had a better preservation effect on large yellow croaker than the Nisin-treated group and control group. This study provides a fundamental knowledge for developing safe and harmless biological preservatives for large yellow croaker.