Carbon-silica composite matrices for preparing heterogeneous biocatalysts with glucose isomerase activity

Abstract

Comparative studies have been carried out on the preparation of carbon-silica composite matrices for heterogeneous biocatalysts with glucose isomerase activity. Carbon nanotubes and nanofibers have been included inside SiO2 xerogel. The enzymatic activity and operating stability of the biocatalysts have been investigated. Bacterial cells of a recombinant glucose isomerase producer strain have been used as the enzymatically active component of the biocatalysts. The steady-state activity of the biocatalysts subjected to “dry” cross linking with a glutaraldehyde solution (0.1–1%) is 1.5 times higher than the activity of the biocatalysts containing no nanocarbon. The initial and steady-state glucose-isomerase activities of the biocatalysts at 70°C are ∼520–540 and ∼150–160 μmol min−1 g−1, respectively. The half-inactivation time of the biocatalysts under continuous monosaccharide (glucose, fructose) isomerization conditions is up to ∼1500 h.