Abstract

Homopolysaccharides produced from sucrose by lactic acid bacteria (LAB) are of interest as natural additives to improve textural properties of foods. The production of exopolysaccharide (EPS) by Weissella strains, which had been isolated from a traditional Thai food (plasom), was investigated using sugarcane molasses and white sugar from sugarcane as substrates in comparison to analytical grade sucrose. EPS production was evaluated at 30°C for 48 h. EPS production and bacterial growth were influenced by the type of carbon source used in culture medium. The highest EPS concentration was obtained in the medium supplemented with white sugar from sugarcane as a sole carbon source by Weissella sp. PSMS4-4. The optimal concentration and factors affecting the production of EPS, that is, cultivation temperature and initial pH of medium, were determined. The highest EPS production of 8.65 g/l was attained in culture with an initial pH of 7.0, temperature of 30°C, and white sugar concentration of 5%. This study shows the first report on the production of Weissella EPS using low-cost substitutes for sucrose and provides knowledge of factors influencing the production of the polymer.

Key words:  Exopolysaccharide, sucrose, white sugar from sugarcane, lactic acid bacteria, Weissella.

Abbreviation

Abbreviations: EPS, Exopolysaccharide; LAB, lactic acid bacteria; GRAS, generally recognized as safe; HPLC, high pressure liquid chromatography; TCA, trichloroacetic acid; PCR, polymerase chain reaction; DNA, deoxyribonucleic acid; MRS, De Man, Rogosa and Sharpe.