Production, purification, immobilization, and characterization of a thermostable β-galactosidase from Aspergillus alliaceus.
A fungal strain isolated from rotten banana and identified as Aspergillus alliaceus was found capable of producing thermostable extracellular β-galactosidase enzyme. Optimum cultural conditions for β-galactosidase production by A. alliaceus were as follows: pH 4.5; temperature, 30 °C; inoculum age, 25 h; and fermentation time, 144 h. Optimum temperature, time, and pH for enzyme substrate reaction were found to be 45 °C, 20 min, and 7.2, respectively, for crude and partially purified enzyme. For immobilized enzyme-substrate reaction, these three variable, temperature, time, and pH were optimized at 50 °C, 40 min, and 7.2, respectively. Glucose was found to inhibit the enzyme activity. The K(m) values of partially purified and immobilized enzymes were 170 and 210 mM, respectively. Immobilized enzyme retained 43 % of the β-galactosidase activity of partially purified enzyme. There was no significant loss of activity on storage of immobilized beads at 4 °C for 28 days. Immobilized enzyme retained 90 % of the initial activity after being used four times.
Department of Food Technology and Biochemical Engineering, Jadavpur University, Kolkata 700032, India.
Sucharita
S
Sen
Lalitagauri
L
Ray
Parimal
P
Chattopadhyay
D001230:Aspergillus / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D004795:Enzyme Stability / Q000187:drug effects; D004800:Enzymes, Immobilized / Q000096:biosynthesis* / Q000302:isolation & purification*; D005690:Galactose / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D006868:Hydrolysis / Q000187:drug effects; D007477:Ions; D007700:Kinetics; D008670:Metals / Q000494:pharmacology; D010802:Phylogeny; D020011:Protective Agents / Q000494:pharmacology; D059027:Recycling; D013696:Temperature; D013997:Time Factors; D001616:beta-Galactosidase / Q000096:biosynthesis* / Q000302:isolation & purification*
D004800:Enzymes, Immobilized; D007477:Ions; D008670:Metals; D020011:Protective Agents; D001616:beta-Galactosidase; D005947:Glucose; D005690:Galactose