Florentina-Daniela Munteanu

Expression system of CotA-laccase for directed evolution and high-throughput screenings for the oxidation of high-redox potential dyes

Laccases are useful biocatalysts for many diverse biotechnological applications. In this study we have established efficient and reliable expression systems and high-throughput screenings for the recombinant CotA-laccase from Bacillus subtilis. The expression levels of cotA-laccase were compared in five different Escherichia coli host strains growing in 96-well microtiter plates under different culture conditions. Lower coefficients of variance (around 15%) were achieved using crude cell lysates of BL21 and KRX host strains growing under microaerobic conditions. Reproducible high-throughput screenings for the decolorization of high redox potential azo and anthraquinonic dyes were developed and optimized for identification of variants with increased redox potential. The enzymatic assays developed were tested for the screening of one mutant library from CotA-laccase created by error-prone PCR.

Protein disulphide isomerase-assisted functionalization of keratin-based matrices

In living systems, protein disulphide isomerase (PDI, EC 5.3.4.1) regulates the formation of new disulphide bonds in proteins (oxidase activity) and catalyzes the rearrangement of non-native disulphide bonds (isomerase activity), leading proteins towards their native configuration. In this study, PDI was used to attach cysteine-containing compounds (CCCs) onto hair, to enhance compound migration within hair fibre and to trigger protein release. A fluorescent (5(6)-TAMRA)-labelled keratin peptide was incorporated into hair by using PDI. Similarly, PDI promoted the grafting of a cysteine-functionalized dye onto wool, as suggested by matrix-assisted laser desorption and ionization time-of-flight results. These reactions were thought to involve oxidation of disulphide bonds between CCCs and wool or hair cysteine residues, catalyzed by the oxidized PDI active site. On the other hand, PDI was demonstrated to enhance the migration of a disulphide bond-functionalized dye within the keratin matrix and trigger the release of RNase A from wool fibres’ surface. These observations may indicate that an isomerisation reaction occurred, catalyzed by the reduced PDI active site, to achieve the thiol-disulphide exchange, i.e. the rearrangement of disulphide bonds between CCCs and keratin. The present communication aims to highlight promising biotechnological applications of PDI, derived from its almost unique properties within the isomerase family.

Characterization of ligno-cellulosic materials bleached with oxo-diperoxo-molybdates

A newly effective system was used to bleach ligno-cellulosic textile materials. This system is based on two different newly synthesized natrium oxo-diperoxo molybdates, Na2[MoO (O2)2(C2O4)] and Na2[MoO (O2)2(C6H6O7)]. These two compounds were characterized by means of cyclic voltammetry, and the bleached fabrics were fully characterized by measuring their whiteness index, percent loss in fabric weight and the content of lignin in the fabric. The obtained results revealed that good whiteness index of the bleached linen-cotton fabrics (50% linen and 50% cotton) and low content of lignin could be obtained by soaking the fabric for 55 min at 90 °C in a solution containing 3.5% of molybdate complex and 3.5% H2O2.

Biosensors Based on Laccase for Detection of Commercially Reactive Dyes

The results obtained using Trametes versicolor laccase modified graphite electrodes for detection of eleven different commercially reactive dyes are presented for the first time herein. The increase in current upon injection of the analyzed substrate was shown to be approximated by Michaelis–Menten type dependence. The calculated kinetic constants were used to evaluate the applicability of the laccase modified graphite electrode for the detection of reactive dyes in textile effluents.

MALDI-TOF Mass Spectrometry in Textile Industry

In this paper are presented the possibilities of using matrix assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry in textile industry. MALDI-TOF mass spectrometry it is a convenient, versatile method for characterization and identification of dyes and pigments, and also for characterization of fibers and contaminants of the fabrics.