5208
Amira Gamal Abd El-Rahim
Production of polysaccharides and oligosaccharides from immobilized dextransucrase produced from honey bacterial isolates
dextransucrase, Enterococcus faecalis, statistical approach, partial purification, immobilization, enzymatic synthesis, dextran, gluco-oligosaccharides, antimicrobial, prebiotic, anticoagulant, fibrinolytic.
This work aimed to produce a potent dextransucrase from bacterial honey isolates. In the present study, the production of dextransucrase and levansucrase was investigated by different bacterial honey isolates. Of twelve tested microorganisms, Enterococcus faecalis Esawy was found to be the most potent for dextransucrase production with no levansucrase production. Different experiments were carried out to optimize the cultural and nutritional conditions for active dextransucrase production, such as: concentration of carbon and nitrogen sources. Medium components and culture conditions were optimized by sequential study using statistical approach. Plackett–Burman design was used to screen the most significant factors affecting enzyme production followed by central composite design (CCD) to identify the optimum levels of the significant variables to generate optimal response for dextransucrase production. Partial purification of the crude enzyme was carried out by fractional precipitation with ethanol, acetone and ammonium sulfate. Dextransucrase production was done by free and immobilized enzymes (immobilization on Alg. CMC FeCl3). General properties ofthe free and immobilized enzymes were studied in comparative study. Production of dextran and gluco-oligosaccharides enzymatically were done by using the immobilized lyophilized dextransucrase. The precipitated dextran and oligosaccharides were characterized and tested for its biological activities, such as: antimicrobial activity, prebiotic activity, anticoagulant and fibrinolytic activites. For our knowledge, Enterococcus faecalis was studied for the first time as a dextransucrase producer
2016
Ph.d
Ain Shams
Science