Optimization and Identification of Lactic Acid Bacteria with Higher Mannitol Production Potential

Abstract

Background: Lactic acid bacteria (LAB) is considered as food-grade microorganism with generally recognized as safe (GRAS) status. Both hetero-fermentative and homo-fermentative LAB have the ability to produce mannitol as metabolic end product in normal fermentation. Methods: Ten LAB isolates selected were detected for its mannitol production potential using colorimetric assay in preliminary study. Later selected four isolates of LAB with better mannitol production were further optimized at different culture conditions. A total of 540 mannitol combinations were obtained after optimization. All the observations were statistically analyzed using response surface methodology. Biochemical and molecular assays were carried out to identify the isolates. Result: The isolate L8 produced mean mannitol content of 1.635 g/L, 0.345967 cell densities, at pH 7.0 and temperature 42°C with agitation of 100 rpm was selected with optimum response surface optimization because of its higher mannitol production. Biochemical and molecular assays identified higher mannitol producers, L4 as Enterococcus faecium strain Gr17, L6 as Lactobacillus rhamnosus strain 6870, L8 as Leuconostoc pseudomesenteroides culture IMAU: 11666 and L9 as Lactobacillus plantarum subsp. plantarum strain NMB8.