Preparation and characterization of sugilite glass from basalt for α-amylase immobilization, statistical optimization of the immobilization process and description of free and immobilized enzyme

Abstract

Bacterial α-amylase was immobilized on sugilite from modified basalt rock as a new carrier. A set of glass compositions based on sugilite formula KNa2M2Li3Si12O30 (M = Al or Mn or Fe) were prepared. The glasses were prepared through melting–quenching technique and samples of glass were converted to glass ceramic. Among the tested glasses and glass ceramic only sugilite glass based on M = Fe (BSF) give promising results. The sugilite BSF glass was characterized using DSC analysis, FTIR absorption, and SEM. The sugilite glass revealed high thermal resistant till ∼770 °C. Under optimized conditions of the Central composite design, the immobilization yield improved by 4.7-fold. The affinity to starch increased after enzyme immobilization by 4.3-fold. The lower rate of deactivation constant and the increase of t½ and D-value confirm the suitability of BSF and immobilization method in enhancing enzyme stability. The improvement in thermostability of immobilized α-amylase was judged by the change in thermodynamic parameters. In conclusion, the prepared sugilite BSF glass can be utilized as a new carrier suitable for stabilization of α-amylase enzyme by immobilization.