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Synergistic chemo-enzymatic hydrolysis of poly (ethylene terephthalate) from textile waste
Felice Quartinello, Simona Vajnhandl, Julija Volmajer Valh, Thomas Farmer, Bojana Vončina, Aleksandra Lobnik, Enrique Herrero Acero, Alessandro Pellis, Georg M. Gübitz, 2017, original scientific article

Abstract: Due to the rising global environment protection awareness, recycling strategies that comply with the circular economy principles are needed. Polyesters are among the most used materials in the textile industry; therefore, achieving a complete poly(ethylene terephthalate) (PET) hydrolysis in an environmentally friendly way is a current challenge. In this work, a chemo-enzymatic treatment was developed to recover the PET building blocks, namely terephthalic acid (TA) and ethylene glycol. To monitor the monomer and oligomer content in solid samples, a Fourier-transformed Raman method was successfully developed. A shift of the free carboxylic groups (1632 cm$^{−1}$) of TA into the deprotonated state (1604 and 1398 cm$^{−1}$) was observed and bands at 1728 and 1398 cm$^{−1}$ were used to assess purity of TA after the chemo-enzymatic PET hydrolysis. The chemical treatment, performed under neutral conditions (T = 250 °C, P = 40 bar), led to conversion of PET into 85% TA and small oligomers. The latter were hydrolysed in a second step using the Humicola insolens cutinase (HiC) yielding 97% pure TA, therefore comparable with the commercial synthesis-grade TA (98%).
Keywords: textile waste, waste recycling
Published: 16.11.2017; Views: 695; Downloads: 244
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The influence of enzymatic treatment on wool fibre properties using PEG-modified proteases
Suzana Jus, Marc Schroeder, Georg M. Gübitz, Elisabeth Heine, Vanja Kokol, 2007, original scientific article

Abstract: The main contribution of the presented work was to introduce the use of proteases modified with the soluble polymer polyethylene glycol (PEG) in the bio-finishing process of wool fibres, to target enzyme action to the outerparts of wool fibres, i.e. to avoid the diffusion and consequent destroying of the inner parts of the wool fibre structure, in the case of native proteases using. Different proteolytic enzymes from Bacillus lentus and Bacillus subtilis in native and PEG-modified forms were investigated and their influence on the modification of wool fibres morphology surface, chemical structure, as well as the hydrolysis of wool proteins, the physico-mechanical properties, and the sorption properties of 1:2 metal complex dye during dyeing were studied. SEM images of wool fibres confirmed smoother and cleaner fibre surfaces without fibre damages using PEG-modified proteases. Modified enzyme products have a benefit effect on the wool fibres felting behaviours (14%) in the case when PEG-modified B. lentus is used, without markedly fibre damage expressed by tensile strength and weight loss ofthe fibre. Meanwhile the dye exhaustion showed slower but comparable level of dye uptake at the end of the dyeing.
Keywords: volnena vlakna, proteolitski encimi, encimske modifikacije, sorpcija barve, morfologija vlaken, wool fibres, proteolytic enzymes, enzyme modification, felting, dye sorption, protein hydrolysis, XPS-analysis, fibre morphology
Published: 01.06.2012; Views: 1896; Downloads: 87
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A novel metalloprotease from Bacillus cereus for protein fibre processing
Fernanda de Sousa, Suzana Jus, Anita Erbel, Vanja Kokol, Artur Cavaco-Paulo, Georg M. Gübitz, 2007, original scientific article

Abstract: A novel protease produced by Bacillus cereus grown on wool as carbon and nitrogen source was purified. B. cereus protease is a neutral metalloprotease with a molecular mass of 45.6 kDa. The optimum activity was at 45 °C and pH 7.0. The substrate specificity was assessed using oxidized insulin B-chain and synthetic peptide substrates. The cleavage of the insulin B-chain was determined to be Asn3, Leu6, His10-Leu11, Ala14, Glu21, after 12 h incubation. Among the peptide substrates, the enzyme did not exhibit activity towards ester substrates; with p-nitroanilide, the kinetic data indicate that aliphatic and aromatic amino acids were the preferred residues at the P1 position. For furylacryloyl peptides substrates, which are typical substrates for thermolysin, the enzyme exhibited high hydrolytic activity with a Km values of 0.858 and 2.363 mM for N-(3-[2-Furyl]acryloyl)-Ala-Phe amide and N-(3-[2-Furyl]acryloyl)-Gly-Leu amide, respectively. The purified protease hydrolysed proteins substrates such as azocasein, azocoll, keratin azure and wool.
Keywords: textile finishing, enzymatic modification, wool fibre, enzymes, Bacilus cereus, specificity, kinetics, metalloprotease
Published: 01.06.2012; Views: 1293; Downloads: 79
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Tyrosinase-catalysed coating of wool fibres with different protein-based biomaterials
Suzana Jus, Vanja Kokol, Georg M. Gübitz, 2009, original scientific article

Abstract: The potential of tyrosinases to activate tyrosine residues of wool protein fibres for cross-linking with different materials like collagen, elastin and gelatine was assessed. Natural fibres like wool offer an excellent environment for the growth of micro-organisms when the conditions like moisture, oxygen and temperature are appropriate. Coating with collagen, a very useful biomaterial with bactericidal and fungicidal properties, could be used to improve the properties of wool-based materials, especially when applied in hygienically sensitive applications like in hospitals. Tyrosinases were shown to catalyse the oxidation of tyrosine residues in wool and wool hydrolysates as model substrates, as determined by UV-Vis spectroscopy. Structural differences of the surface were evident from the increase of the intensity in the NH bending and stretching regions in the spectra of NIR FT Raman analysis of the enzyme treated and grafted wool fibres. The durability of the coating was also shown by using FITC-labelled collagen that was bound to the wool fibres, even after severe washing. Additionally, antimicrobial properties were successfully imparted due to the collagen grafted on the wool fibres. The functional and mechanical properties of the treated wool fibres showed no significant changes.
Keywords: textile fibres, wool, protein substrates, tyrosinase, enzymatic coupling, antimicrobial properties, coating
Published: 01.06.2012; Views: 1124; Downloads: 69
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Process of dyeing cellulose and polyamide textile materials with enzyme reduced indigo : Pub. No.: WO/2009/051569; International Application No.: PCT/SI2008/000054; Publication Date: 23.04.2009; International Filing Date: 17.10.2008
Mojca Božič, Georg M. Gübitz, Vanja Kokol, 2009, patent

Abstract: This invention concerns an ecologically friendly process of indigo (C.I. Vat Blue 1 ) dyeing of cellulose and polyamide-containing textile material with possibility of reusing (three or more times) the enzyme reduction dyeing bath. Procedure of dyeing cellulose and polyamide textile materials with enzymatically reduced indigo comprising the step of subjecting the cellulose or polyamide samples to the indigo dyebath containing reductases (e.g. NADH-dependent enzymes from Bacillis subtilis in the presence of a redox mediator (e.g.1,8- dihydroxy-9,10-anthraquinone), oxidation on air or oxidases enzyme or oxidizing agent (i.e. hydrogen peroxide) after diffusion leuko indigo into material and finally soaping and washing.
Published: 31.05.2012; Views: 1053; Downloads: 33
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Enzyme mediated coupling of protein-based biomaterials onto wool fibres
Suzana Jus, Georg M. Gübitz, Vanja Kokol, 2008, published scientific conference contribution abstract

Keywords: wool protein fibres, tyrosinase, grafting
Published: 31.05.2012; Views: 1232; Downloads: 34
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Tyrosinase catalysed coupling of functional molecules onto protein fibres
Suzana Jus, Vanja Kokol, Georg M. Gübitz, 2008, original scientific article

Abstract: Grafting, using oxidative enzymes shows a high potential for wool fibres funktionalisation. In this work we attempt to graft on wool fibres with phenolic antioxidants order to introduce and improve the properties of the fibre. The approach of tyrosinase to oxidize tyrosine residues in wool proteins to quinones, which can further react with free sulfhydryl (thiol), amino or phenolic groups of different substrates was exploited to couple different phenolic antioxidants (caffeic acid and chlorogenic acid) onto the wool fibre proteins. Tyrosinase catalysed reactions were followed by different analytical methods like oxygen consumption, FT-NIR Raman and UV/VIS spectroscopy. It was proved that phenolic compounds used are strongly cross-linked on the wool fibre resulting to an improved antioxidant activity.
Keywords: textile fibres, wool fibers, tyrosinase, caffeic acid, chlorogenic acid, grafting, chemical modification of fibres
Published: 31.05.2012; Views: 1177; Downloads: 75
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