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Rivista di Biologia Molecolare e Biotecnologie

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Minerva Biotecnologica 2006 March;18(1):23-9

lingua: Inglese

Synthesis, structure and application of new hybrid nanomaterials for cell immobilization

Kaibanova L., Dobreva E., Emanuilova E., Chernev G., Samuneva B., Salvado I.

1 Department of Extremophilic Bacteria Institute of Microbiology Bulgarian Academy of Sciences, Sofia, Bulgaria
2 Department of Glass Technology University of Chemical Technology and Metallurgy, Sofia, Bulgaria
3 University of Aveiro, Aveiro, Portugal


Aim. Whole cells of the thermophilic bacterial strain UG-5B with benzonitrile degrading activity were immobilized in nanocomposite hybrid materials, prepared by the sol gel method at room temperature. Full entrapment (100%) of the used cells in the matrices was established.
Methods. Two types of inorganic precursors were used: tetraethylortosilicate (TEOS) and tetramethylortosylicate (TMOS) and the replacement of them with 5% polyacrylamide gel lead to faster polymerisation and good operational stability of the obtained biocatalysts.
Results. When TMOS was used instead of TEOS, the complete homogenization of the precursor solution was more easily obtained. This reaction is quite exothermic and no ethanol was found in the mixture which feature favors preservation of the functions of biomolecules. The strictly controlled pH conditions helped for keeping cell vitality and enzyme activity. Nitrilase activity was used for 10 reaction cycles and enhanced operational stability was observed when 5 mL of the cell suspension with 19 mg/mL dry cells and enzyme activity of 1.4 U/mL was included in TMOS containing carriers. The residual enzyme activity was calculated in percent according to the total activity of cell suspension (7 U). The entrapped cells retained 64% of the initial activity (assumed as 100%) after 10 reaction cycles in fresh substrate solution for benzonitrile degradation.
Conclusion. The sol gel hybrid matrices appeared to be suitable carriers that preserve cell vitality and the biocatalysts obtained can be successfully used in the nitrile degradation process.

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