Sour fermented rice products: A rich source of lactic acid bacteria

Aims: This study aimed to isolate and determine the antimicrobial activity of lactic acid bacteria (LAB) isolated from sour Vietnamese fermented rice in Ninh Kieu, Can Tho City, Vietnam.Methodology and results: Thirteen LAB strains were isolated from seven sour Vietnamese fermented rice samples using MRS agar supplemented with 1% CaCO3.The isolated LAB strains exhibited round, smooth, raised, and entire characteristics (69.23%), were milky white and ranged from 1.5 to 2.0 mm in size (84.62%), and were rod-shaped, Gram-positive, and catalase and oxidase negative (100%).Antibacterial activity against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923 was observed in cell-free supernatants of thirteen LAB strains using the agar well diffusion method.Twelve out of the thirteen strains (92.31%) showed antibacterial activity against both indicator bacteria strains, with strain AN2 exhibiting the highest antibacterial activity (IZ= 8.67 mm and 8.33 mm, respectively).The AN2 strain did not have antifungal activity against Saccharomyces sp. and Aspergillus sp.The AN2 strain was identified as Lactobacillus paracasei based on 16S rRNA gene and morphological and biochemical characteristics.Conclusion, significance and impact of study: Identifying the LAB strains from sour Vietnamese fermented rice have antibacterial properties.