Calcination was considered for the first time as an alternative to recover inorganic bone component from spent glucoamylase-bone derivatives. The subsequent adsorption of glucoamylase (GA) onto calcined bone particles was assessed. Adsorption capacity of the calcined matrix was found to be from 1.1- to 1.4-fold superior to that of non-calcined supports, and it was dependent on the applied load. Moreover, the expressed activity of GA derivatives on calcined matrix was, at least, 2-fold higher than that of biocatalysts onto non-calcined support. The optimization of the loading allowed the preparation of derivatives with 139 GA units per gram of support, which preserve 52% of the immobilized activity. Additionally, calcination of spent GA biocatalysts on calcined bone particles was performed, and adsorption of glucoamylase onto the bone particles calcined a second time was also found to be efficient. In addition to the improved catalytic properties, the half-life at 55°C of the GA biocatalysts on calcined bone was increased 1.7-fold in comparison with that of soluble GA and GA adsorbed onto non-calcined bone particles. Furthermore, the same cassava starch conversion can be achieved batchwise in a stirred-tank reactor using less insoluble biocatalyst, 37% of the GA-bone derivative, which represents an important saving for industrial applications. © 2009 Springer Science + Business Media, LLC.
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