Response surface methodology: Synthesis of short chain fructooligosaccharides with a fructosyltransferase from Aspergillus aculeatus

• Published in: Bioresource technology Vol. 100; no. 6; pp. 2040 - 2045
• Main Authors: Nemukula, A., Mutanda, T., Wilhelmi, B.S., Whiteley, C.G.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.03.2009; [New York, NY]: Elsevier Ltd; Elsevier
• Subjects: Aspergillus - enzymology; Aspergillus aculeatus; Biological and medical sciences; enzyme activity; enzyme kinetics; Enzyme Stability; Fructooligosaccharides; fructosyltransferase; Fundamental and applied biological sciences. Psychology; hexosyltransferases; Hexosyltransferases - isolation & purification; Hexosyltransferases - metabolism; Hydrogen-Ion Concentration; inulin; Kinetics; Molecular Weight; Oligosaccharides - biosynthesis; Response surface; response surface methodology; Synthesis; Temperature; Transferase; Response surface; Synthesis; Transferase; Fructooligosaccharides; Fungi; Short chain; Enzyme; Aspergillus aculeatus; Transferases; Fungi Imperfecti; Oligofructose
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2008.10.022

A transferase was isolated, purified and characterised from Aspergillus aculeatus. The enzyme exhibited a pH and temperature optima of 6.0 and 60 °C, respectively and under such conditions remained stable with no decrease in activity after 5 h. The enzyme was purified 7.1 fold with a yield of 22.3% and specific activity of 486.1 U mg −1 after dialysis, concentration with polyethyleneglycol (30%) and DEAE-Sephacel chromatography. It was monomeric with a molecular mass of 85 kDa and K m and V max values of 272.3 mM and 166.7 μmol min −1 ml −1. The influence of pH, temperature, reaction time, and enzyme and sucrose concentration on the formation of short-chain fructooligosaccharides (FOS) was examined by statistical response surface methodology (RSM). The enzyme showed both transfructosylation and hydrolytic activity with the transfructosylation ratio increasing to 88% at a sucrose concentration of 600 mg ml −1. Sucrose concentration (400 mg ml −1) temperature (60 °C), and pH (5.6) favoured the synthesis of high levels of GF 3 and GF 4. Incubation time had a critical effect on the yield of FOS as the major products were GF 2 after 4 h and GF 4 after 8 h. A prolonged incubation of 16 h resulted in the conversion of GF 4 into GF 2 as a result of self hydrolase activity.