Surface Modification of Cellulose Acetate with Cutinase and ...

Abstract
The challenges facing the textile finishing industry have intensified during the last
decade. Current awareness of the negative environmental impact of chemical processing
in textile industry, combined with increased strict legislation on industrial effluents, has
led to the search for advanced, non-polluting processes, for treating both natural and
synthetic fibre fabrics. Enzymes can represent good alternatives for the traditional
textile processes allowing not only the reduction of costs, the protection of the
environment, and increasing safety of employees but also contributing for the
improvement of the quality and functionality of the final products.
In the present work biotechnological approaches and genetic engineering methods were
used aiming at the development and optimization of enzymatic eco-friendly processes
for surface modification of synthetic and natural fibres.
A general introduction is presented in Chapter 1 where an extensive bibliographic
revision concerning the use of enzymes in textile industry is presented, through the
identification and description of the major commercial processes, and the most recent
developments obtained in this field.
Chapter 2 deals with the surface modification of synthetic fibres by recombinant
cutinase from the phytopathogenic fungus Fusarium solani pisi produced by molecular
genetics tools. The Subchapter 2.1 is an introduction to the synthetic fibres utilized in
the scope of this work. Subchapter 2.2 reports the structural modulation studies that
allowed the identification of the aminoacids L81, N84, L182, V184 and L189 as targets
to be substituted by Alanine allowing a better fit of large susbtrates in the active site of
cutinase. All the mutations were obtained by site-directed mutagenesis and
heterologously expressed in Escherichia coli. The genetically modified cutinase L182A
presented higher stabilization on polyamide 6,6 (PA 6,6) and polyethylene terephthalate
(PET) model substrates, a mutant variant that was chosen for further studies concerning
the design and optimization of processes for functionalization of both fibres
(Subchapters 2.3 and 2.4, respectively). Optimization of native enzyme was also
performed, for the surface modificationof cellulose acetate, by creating chimeric fusions
of the cutinase DNA coding sequence with either the fungal carbohydrate-binding
xi