We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
Kinetic characterization of extracellular α-amylase from a derepressed mutant of Bacillus licheniformis.
- Authors
Ikram-ul-Haq; Hamad Ashraf; Sikander Ali; M. Qadeer
- Abstract
Abstract Three strains ofBacillus licheniformis were isolated and screened for α-amylase production by solid-state fermentation. Of these, IS-2 gave relatively higher enzyme production (32�2.3 U/[g�min]) and was selected for improvement after treatment withN-methylN-nitroN-nitroso guanidine (NG) or nitrous acid (NA) to enhance its hydrolytic potential. Among the mutant variants, NA-14 gave higher enzyme production (98�1.6 U/[g�min]), and hence, was selected for kinetic and thermal characterization. M1 as a moistening agent (pH 7.0, optimized) supported 2.65-fold improved amylolytic activity by the derepressed mutant 72 h after inoculation. The values of product yield coefficient (Y p/x=1833.3 U/g) and specific rate constant (q p=25.46 U/[g�h]) with starch were severalfold improved over those from other carbon sources and the other cultures. The purified enzyme from NA-14 was most active at 40�C; however, the activity remained almost constant up to 44�C. The NA-induced random mutagenesis substantially improved the enthalpy (ΔH D=94.5�11 kJ/mol) and entropy of activation (ΔS=−284�22 J/[mol�K]) for α-amylase activity and substrate binding for starch hydrolysis. The results of this study (117.8�5.5 U/[g�min]) revealed a concomitant improvement in the endogenous metabolism of the mutant culture for α-amylase production.
- Subjects
HYDROGEN-ion concentration; INDUSTRIAL microbiology; RADIOGENETICS; BIOCHEMISTRY
- Publication
Applied Biochemistry & Biotechnology, 2007, Vol 141, Issue 2/3, p251
- ISSN
0273-2289
- Publication type
Article
- DOI
10.1007/BF02729066