Abstract: In this study, lactic acid bacteria (LAB) with antioxidant activity were isolated from the intestinal tract of seawater and freshwater fish for use in the prevention and attenuation of oxidative deterioration during the processing of aquatic products. The results were showed that five LAB strains with strong antioxidant activity were screened from the 48 LAB strains, among which strain CY1-2 from the intestinal tract of grass carps exhibited the strongest antioxidant activity. The antioxidant activity of the cells of this strain was determined to be (67.29 ± 0.42)%, (60.67 ± 1.44)% and (29.87 ± 1.14)% in the scavenging of 1,1-diphenyl-2-picryl-hydrazyl-hydrate (DPPH), hydroxyl and superoxide anion radicals and (40.77 ± 0.50)% in the inhibition of lipid peroxidation, respectively, and the percentages of hydroxyl and superoxide anion radical scavenging effect and anti-lipid peroxidation effect of the cell-free extract were (64.27 ± 1.26)%, (21.97 ± 1.47)%, and (51.03 ± 0.40)%, respectively. In addition, strain CY1-2 exhibited antibacterial activity against both gram-positive bacteria and gram-negative bacteria, including Bacillus licheniformis, Staphylococcus aureus, B. cereus, Shigella sp., Escherichia coli, Pseudomonas aeruginosa and Pseudomonas fluorescens. It was identified as Lactobacillus plantarum by physiological and biochemical characterization and 16S rDNA sequence analysis. Owing to its strong broad-spectrum antibacterial activity L. plantarum CY1-2 has the potential to be developed as a novel natural microorganism-derived antioxidant from aquatic products.

Key words: intestinal tract of fish; lactic acid bacteria; antioxidant; antimicrobial; screening and identification