From inulin to fructose syrups using sol-gel immobilized inulinase.

The present work aims to provide the basic characterization of sol-gel immobilized inulinase, a biocatalyst configuration yet unexploited, using as model system the hydrolysis of inulin to fructose. Porous xerogel particles with dimensions in slight excess of 10 μm were obtained, yielding an immobilization efficiency of roughly 80%. The temperature- and pH-activity profiles displayed a broader bell-shaped pattern as a result of immobilization.

Improved specific productivity in cephalexin synthesis by immobilized PGA in silica magnetic micro-particles.

There is a marked trend in pharmaceutical industry towards the replacement of classical organic methods by "green" alternatives that minimize or eliminate the generation of waste and avoid, where possible, the use of toxic and/or hazardous reagents and solvents. In this work the kinetically controlled synthesis of cephalexin by soluble and penicillin G acylase immobilized in sol-gel micro-particles with magnetic properties was performed in aqueous media with PGME and 7-ADCA as substrates, at different concentrations of substrate, temperature, pH, enzyme to substrate ratio and acyl donor to nucleophile ratio. Excess acyl donor had a strong effect on cephalexin productivity.

A new biocatalyst: Penicillin G acylase immobilized in sol-gel micro-particles with magnetic properties.

The present work focuses on the development and basic characterization of a new magnetic biocatalyst, namely penicillin G acylase (PGA), immobilized in sol-gel matrices with magnetic properties, ultimately aimed for application in cephalexin (CEX) synthesis. A mechanically stable carrier, based on porous xerogels silica matrixes starting from tetramethoxysilane (TMOS), was prepared leading to micro-carriers with medium sized particles of 30 microm, as determined by scanning electron microscopy. An immobilization yield of 95-100% and a recovered activity of 50-65% at 37 degrees C, as determined by penicillin G (PG) hydrolysis (pH STAT method), were observed.