Screening, identification and biological characteristics of lactic acid bacteria inhibiting Vibrio parahaemolyticus

Abstract

Objective: This study aimed to enrich the functional lactic acid bacteria resource bank and to search for excellent starting strains of lactic acid bacteria with the antagonistic ability of Vibrio parahaemolyticus. Methods: Lactobacillus strains with broad-spectrum bacteriostatic potential were screened by Oxford cup bacteriostatic test, and their biological characteristics were discussed by growth and metabolic performance, gastrointestinal fluid tolerance, salt tolerance, antibiotic sensitivity and bacteriostatic spectrum. Results: Six strains of lactic acid bacteria were screened by using V. parahaemolyticus as indicator bacteria. They were classified into L. paracasei, L. fermentus and L. plantarum by morphological, physiological and biochemical identification and molecular biological identification. Among them, the bacteriostatic activity of L. paracasei A1 was the best, the total number of colonies within 24 hours exceeded 1×109 CFU/mL, and the pH value of fermentation broth was stable at about 4.1. After artificial simulated gastric juice treatment for 2 h, the survival rate was 54.61%. After artificial simulated intestinal juice treatment for 8 h, the survival rate still reached 45.46%. After 10% NaCl stress treatment for 24 h, the total number of viable bacteria was ＞ 1×105 CFU/mL. Moreover, the crude bacteriocin extract of L. paracasei A1 showed good antibacterial activity against 13 pathogenic bacteria, had broad-spectrum antibacterial potential, and no resistance to 8 common antibiotics was found. Conclusion: L. paracasei A1, which can inhibit V. parahaemolyticus and has excellent biological characteristics, was obtained.

Keywords

• vibrio parahaemolyticus
• lactobacillus paracasei
• screening
• identification
• biological characteristics