Immobilization of recombinant E. coli thermostable lipase by entrapment inside silica xerogel and nanocarbon-in-silica composites

The multi-component heterogeneous biocatalysts were prepared by entrapment of whole cells or cells' lysates of a recombinant strain Escherichia coli producing of thermostable lipase from Thermomyces lanuginosus (rE.coli/lip) inside silica xerogel and nanocarbon-in-silica composites. The properties of intracellular recombinant lipase and the prepared heterogeneous biocatalysts, such as enzymatic activity and stability, were studied in periodic process of triglycerides' hydrolysis and interesterification. The thermal stability of recombinant lipase was studied by the heating bacteria rE.coli/lip in a buffer and olive oil at 60-100 degrees C. The effects of nanocarbons included inside SiO2-xerogel, such as multi-walled carbon nanotubes with different diameters and dispersity, and nano-onion, on the properties of multi-component biocatalysts were investigated. The {nanocarbon-in-silica} biocatalysts prepared by entrapping cells' lysates of rE.coli/lip together with aggregated thick nanotubes (20-22 nm in diameter) were found to possess the highest hydrolytic activity close to 1000 LU/g. The activity of composite biocatalysts containing cells' lysates of rE.coli/lip and dispersed thin nanotubes (9-11 nm in diameter) did not exceed 400 LU/g. The similar effect of nanocarbons' inclusion inside multi-component biocatalysts on the activities of entrapped whole cells, cells' lysates and purified recombinant lipase was revealed. (C) 2013 Elsevier B.V. All rights reserved.