Screening of Lactic Acid Bacteria Isolated from Fermented Food for Bio-molecules Production

Abstract

Production of bio-molecules is an important factor in assuring the proper consistency and texture of fermented foods. Lactic acid bacteria (LAB) isolated from fermented food were screened for lactic acid, diacetyl, hydrogen peroxide, pH development and Exopolysaccharide (EPS) production. Thirty-five strains of LAB were isolated and characterized from fermented dairy and non-dairy foods. The LAB species identified include: Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus cellobiosus, Lactobacillus delbruekii, Lactobacillus coryniformis, Lactobacillus casei, and Leuconostoc messenteroides. The most predominant species was Lactobacillus plantarum (34.29%). All the isolates were screened for lactic acid, hydrogen peroxide, diacetyl and pH and EPS production. Lactic acid production ranges within 0.11-1.96 mg/l in which the highest was produced by L. plantarum LPF2. L. plantarum LPF2 also produced the largest amount of diacetyl (1.92 mg/l). Hydrogen peroxide produce by the isolates ranges within 0.0002-.35 mg/l and L. fermentum LFBO1 produced the highest. The pH ranged within 3.2-6.5 in which L. plantarum LPF2 had the least. L. plantarum LPW7 and LPBO9, Leu. messenteroides LMWO2 and LMW4 bring the reduction of the pH of the fermentation medium to 3.8 at 36 hours. All the isolates were screened for EPS production on solid medium. The isolates were all creamy; four were highly mucoid, eight were mucoid while twenty-three were slightly mucoid. All the isolates are EPS producers, EPS production ranged within 120-1,390 mg/l in which the highest was produced by L. fermentum LF6.