Study on Increased Fructosyltranseferase (levansucrase) Production by Optimizing Culture Condition from Pediococcus acidilactici Strain in Shaking Batch Cultures

Microbial fructosyltransferases (levansucrases) are polymerases that are involved in microbial fructan

(levan, inulin and fructo-oligosaccharide) biosynthesis. Levan has potential importance in food, pharmaceutical, medicine, cosmetics and textile industry. Structurally, microbial fructosyltransferase proteins share the catalytic domain of glycoside hydrolases 68 family and are grouped in seven phylogenetically related clusters. The aim of the work was screening the potency of some bacterial isolates to produce extracellular levansucrase. Bacteria were isolated from different sources (oral swab, spoiled milk, spoiled whey, and spoiled yoghurt). Pediococcus acidilactici showed the highest levansucrase activity after 2 days fermentation under shacking condition yielding (12.64 U/ml), and maximum levan production (15.4 g/L). Following, the optimization of carbon source, nitrogen source, temperature and initial pH of the growth medium in submerged liquid cultures. Sucrose at 30% (w/v) was the most efficient inducer for levansucrase production. The optimal temperature and pH of the levansucrase activity were 30°C and 6.0, respectively. The crude levansucrase of Pediococcus acidilactici extract was enriched using selected precipitating agents. The results show that ethanol (65% saturation) provided the highest purification factor of 3- fold with a recovery yield of 41.05% as a total highest recovered protein. The optimum reaction temperature and pH of semi purified levansucrase were 40°C, 5.2, respectively. Analysis of the partial purified enzyme preparation by SDS–PAGE revealed one protein band showing levansucrase activity. The molecular weight of this band was estimated to be around 50.000 Daltons. Results of this study suggest that the levansucrase from Pediococcus acidilactici is quite efficient in converting sucrose to levan, which promising as a food additive and in medicine as a plasma substitute, drug activity prolongator and an antihyperlipidemic agent also has anti-diabetic effects.