Isolation, identification, and biochemical characterization of five Lacticaseibacillus strains from Oggtt: A traditional fermented and dried buttermilk.

This study investigates the isolation and characterization of the main lactic acid bacteria responsible for fermentation of Oggtt, a dried fermented buttermilk. Five isolates with Gram-positive staining and negative catalase and oxidase activity were identified using phenotypic and genotypic methods, and their antagonistic, exopolysaccharides and organic acid production, proteolytic activity, and antioxidant capacity were assessed. The isolates are classified as Lacticaseibacillus paracasei Ogt_1, Lacticaseibacillus casei Ogt_2, Lacticaseibacillus paracasei Ogt_3, Lacticaseibacillus paracasei Ogt_4, and Lacticaseibacillus paracasei Ogt_5. All strains possessed high antagonistic activity against Proteus vulgaris, Staphylococcus aureus, and Escherichia coli. All strains produced high levels of lactic acid (11177.3-15404.9 µg/ml), tartaric acid (2197.8-4058.5 µg/ml), and exopolysaccharides(20.86-239.9 mg/L) and possessed high proteolytic and antioxidant activity at variable manners. Overall, this study indicates the isolation of important Lacticaseibacillus strains from Oggtt, which could be used as starter cultures for developing functional foods.