G M Guebitz

Austrian Centre of Industrial Biotechnology, Gratz, Styria, Austria

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Publications (79)188.31 Total impact

  • Biomedizinische Technik/Biomedical Engineering 09/2013; · 1.16 Impact Factor
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    ABSTRACT: Plant cell wall structures represent a barrier in the biodegradation process to produce biogas for combustion and energy production. Consequently, approaches concerning a more efficient de-polymerisation of cellulose and hemicellulose to monomeric sugars are required. Here, we show that natural activated zeolites (i.e. trace metal activated zeolites) represent eminently suitable mineral microhabitats and potential carriers for immobilisation of microorganisms responsible for anaerobic hydrolysis of biopolymers stabilising related bacterial and methanogenic communities. A strategy for comprehensive analysis of immobilised anaerobic populations was developed that includes the visualisation of biofilm formation via scanning electron microscopy and confocal laser scanning microscopy, community and fingerprint analysis as well as enzyme activity and identification analyses. Using SDS polyacrylamide gel electrophoresis, hydrolytical active protein bands were traced by congo red staining. Liquid chromatography/mass spectroscopy revealed cellulolytical endo- and exoglucanase (exocellobiohydrolase) as well as hemicellulolytical xylanase/mannase after proteolytic digestion. Relations to hydrolytic/fermentative zeolite colonisers were obtained by using single-strand conformation polymorphism analysis (SSCP) based on amplification of bacterial and archaeal 16S rRNA fragments. Thereby, dominant colonisers were affiliated to the genera Clostridium, Pseudomonas and Methanoculleus. The specific immobilisation on natural zeolites with functional microbes already colonising naturally during the fermentation offers a strategy to systematically supply the biogas formation process responsive to population dynamics and process requirements.
    Applied Microbiology and Biotechnology 02/2013; · 3.69 Impact Factor
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    ABSTRACT: BACKGROUND: Neutrophilic polymorphonuclear leukocytes play a crucial role in the host defence against bacterial and fungal infections. They participate in the inflammatory response through the liberation of peptides and enzymes like myeloperoxidase (MPO). Therefore, MPO has a potential as a marker enzyme for the diagnosis of wound infection. METHODS: Substrate specificities and reaction pathways of MPO were investigated for new MPO substrates: crystal violet, leuco crystal violet, fast blue RR (4-benzoylamino-2,5-dimethoxybenzenediazonium chloride hemi(zinc chloride) salt) and various systematically substituted model substrates based on 2,7-dihydroxy-1-(4-hydroxyphenylazo)naphtalene-3,6-disulphonic acid. In addition, fast blue RR was covalently bound to siloxanes allowing immobilization of the substrate, while cellobiosedehydrogenase was integrated for generation of hydrogen peroxide required by MPO. RESULTS: Elevated concentrations of MPO were found in infected wounds compared with non-infected wounds (92.2 ± 45.0 versus 1.9 ± 1.8 U/mL). Various soluble and immobilized substrates were oxidized by MPO in wound samples and the influence of substrate structure and reaction pathways were elucidated for selected compounds. CONCLUSIONS: Incubation of different MPO substrates with infected wound fluid samples resulted in a clear colour change in the case of elevated MPO concentrations, thus allowing early diagnosis of wound infection.
    Annals of Clinical Biochemistry 02/2013; · 1.92 Impact Factor
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    ABSTRACT: Alkyd resins are polyesters containing unsaturated fatty acids that are used as binding agents in paints and coatings. Chemical drying of these polyesters is based on heavy metal catalyzed cross-linking of the unsaturated fatty acid moieties. Among the heavy-metal catalysts, cobalt complexes are the most effective, yet they have been proven to be carcinogenic. Therefore, strategies to replace the cobalt-based catalyst by environmentally friendlier and less toxic alternatives are under development. Here, we demonstrate for the first time that a laccase–mediator system can effectively replace the heavy-metal catalyst and cross-link alkyd resins. Interestingly, the biocatalytic reaction does not only work in aqueous media, but also in a solid film, where enzyme diffusion is limited. Within the catalytic cycle, the mediator oxidizes the alkyd resin and is regenerated by the laccase, which is uniformly distributed within the drying film as evidenced by confocal laser scanning microscopy. During gradual build-up of molecular weight, there is a concomitant decrease of the oxygen content in the film. A new optical sensor to follow oxygen consumption during the cross-linking reaction was developed and validated with state of the art techniques. A remarkable feature is the low sample amount required, which allows faster screening of new catalysts.
    Green Chemistry 02/2013; 15(2):381. · 6.83 Impact Factor
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    ABSTRACT: The effect of processing method on the properties of cross-linked chitosan microparticles and on the enzymatic activity of laccase immobilized in the particles has been investigated. Chitosan has been cross-linked by tri-polyphosphate (TPP) using two methods – the so called ex situ cross-linking whereby the solutions of chitosan, TPP and the enzyme have been pre-mixed and spray-dried by a standard two-fluid kinetic nozzle, and a novel in situ cross-linking method, whereby the solutions have been contacted at the tip of a three-fluid nozzle and cross-linking occurred within a drying droplet. The influence of the cross-linking method on the particle size and morphology, surface charge, and swelling ratio has been determined. The enzymatic activity of laccase toward the oxidation of a chromophore substrate (ABTS) has been systematically investigated and found to be superior in particles produced by the in situ cross-linking method.
    Food and Bioproducts Processing 01/2013; 91(4):525–533. · 1.86 Impact Factor
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    ABSTRACT: Activated synovial macrophages play a key role in Rheumatoid Arthritis (RA). Recent studies have shown that folate receptor beta (FRβ) is specifically expressed by activated macrophages. Therefore a folate-based nanodevice would provide the possibility of delivering therapeutic agents to activated macrophages without affecting normal cells and tissues. This study shows for the first time the sonochemical preparation of HSA nanocapsules avoiding toxic cross linking chemicals and emulsifiers used in other methods. Production of HSA nanocapsules was optimized leading to a diameter of 443.5 ± 9.0 nm and a narrow size distribution indicated by a polydispersity index (PDI) of 0.066 ± 0.080. Nanocapsules were surface modified with folic acid (FA) and the FA content was determined to be 0.38 and 6.42 molecules FA per molecule HSA, depending on the surplus of FA employed. Dynamic light scattering was used to determine size, PDI and zetapotential of the produced nanocapsules before and after surface modification. FA distribution on the surface of HSA nanocapsules was localized three-dimensionally after fluorescence labeling using confocal laser scanning microscopy (CLSM). Furthermore, specific binding and internalization of HSA nanocapsules by FRβ-positive and FRβ-negative macrophages, obtained from human peripheral blood mononuclear cells, was demonstrated by flow cytometry. FRβ-expressing macrophages showed an increased binding for FA-modified capsules compared with those without FA.
    International Journal of Pharmaceutics 02/2012; 427(2):460-6. · 3.99 Impact Factor
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    ABSTRACT: A large strain collection comprising antagonistic bacteria was screened for novel detergent proteases. Several strains displayed protease activity on agar plates containing skim milk but were inactive in liquid media. Encapsulation of cells in alginate beads induced protease production. Stenotrophomonas maltophilia emerged as best performer under washing conditions. For identification of wash-active proteases, four extracellular serine proteases called StmPr1, StmPr2, StmPr3 and StmPr4 were cloned. StmPr2 and StmPr4 were sufficiently overexpressed in E. coli. Expression of StmPr1 and StmPr3 resulted in unprocessed, insoluble protein. Truncation of most of the C-terminal domain which has been identified by enzyme modeling succeeded in expression of soluble, active StmPr1 but failed in case of StmPr3. From laundry application tests StmPr2 turned out to be a highly wash-active protease at 45°C. Specific activity of StmPr2 determined with suc-L-Ala-L-Ala-L-Pro-l-Phe-p-nitroanilide as the substrate was 17±2U/mg. In addition we determined the kinetic parameters and cleavage preferences of protease StmPr2.
    Journal of Biotechnology 01/2012; 157(1):140-7. · 3.18 Impact Factor
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    ABSTRACT: In the present study, we developed an enzyme-linked immunosorbent assay (ELISA) for microbial transglutaminase (mTG) from Streptomyces mobaraensis to overcome the lack of a quantification method for mTG. We further performed a detailed follow-on-analysis of insoluble porcine collagen type I enzymatically modified with mTG primarily focusing on residuals of mTG. Repeated washing (4 ×) reduced mTG-levels in the washing fluids but did not quantitatively remove mTG from the material (p < 0.000001). Substantial amounts of up to 40% of the enzyme utilized in the crosslinking mixture remained associated with the modified collagen. Binding was non-covalent as could be demonstrated by Western blot analysis. Acidic and alkaline dialysis of mTG treated collagen material enabled complete removal the enzyme. Treatment with guanidinium chloride, urea, or sodium chloride was less effective in reducing the mTG content.
    European journal of pharmaceutics and biopharmaceutics: official journal of Arbeitsgemeinschaft fur Pharmazeutische Verfahrenstechnik e.V 11/2011; 80(2):282-8. · 3.15 Impact Factor
  • Georg Guebitz
    Biotechnology Journal 10/2011; 6(10):1167. · 3.71 Impact Factor
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    ABSTRACT: The colonisation of activated zeolites (i.e. clinoptilolites) as carriers for microorganisms involved in the biogas process was investigated. Zeolite particle sizes of 1.0-2.5mm were introduced to anaerobic laboratory batch-cultures and to continuously operated bioreactors during biogas production from grass silage. Incubation over 5-84 days led to the colonisation of zeolite surfaces in small batch-cultures (500 ml) and even in larger scaled and flow-through disturbed bioreactors (28 l). Morphological insights were obtained by using scanning electron microscopy (SEM). Single strand conformation polymorphism (SSCP) analysis based on amplification of bacterial and archaeal 16S rRNA fragments demonstrated structurally distinct populations preferring zeolite as operational environment. via sequence analysis conspicuous bands from SSCP patterns were identified. Populations immobilised on zeolite (e.g. Ruminofilibacter xylanolyticum) showed pronounced hydrolytic enzyme activity (xylanase) shortly after re-incubation in sterilised sludge on model substrate. In addition, the presence of methanogenic archaea on zeolite particles was demonstrated.
    Bioresource Technology 03/2011; 102(6):4353-9. · 5.04 Impact Factor
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    ABSTRACT: In this study cutinases from Thermobifida cellulosilytica DSM44535 (Thc_Cut1 and Thc_Cut2) and Thermobifida fusca DSM44342 (Thf42_Cut1) hydrolyzing poly(ethylene terephthalate) (PET) were successfully cloned and expressed in E.coli BL21-Gold(DE3). Their ability to hydrolyze PET was compared with other enzymes hydrolyzing natural polyesters, including the PHA depolymerase (ePhaZmcl) from Pseudomonas fluorescens and two cutinases from T. fusca KW3. The three isolated Thermobifida cutinases are very similar (only a maximum of 18 amino acid differences) but yet had different kinetic parameters on soluble substrates. Their k(cat) and K-M values on pNP-acetate were in the ranges 2.4-211.9 s(-1) and 127-200 AIM while on pNP-butyrate they showed k(cat) and K-m values between 5.3 and 195.1 s(-1) and between 1483 and 2133 mu M. Thc_Cut1 released highest amounts of MHET and terephthalic acid from PET and bis(benzoyloxyethyl) terephthalate (3PET) with the highest concomitant increase in PET hydrophilicity as indicated by water contact angle (WCA) decreases. FTIR-ATR analysis revealed an increase in the crystallinity index A(1340)/A(1410) upon enzyme treatment and an increase of the amount of carboxylic and hydroxylic was measured using derivatization with 2-(bromomethyl)naphthalene. Modeling the covalently bound tetrahedral intermediate consisting of cutinase and 3PET indicated that the active site His-209 is in the proximity of the 0 of the substrate thus allowing hydrolysis. On the other hand, the models indicated that regions of Thc_Cut1 and Thc_Cut2 which differed in electrostatic and in hydrophobic surface properties were able to reach/interact with PET which may explain their different hydrolysis efficiencies.
    Macromolecules 01/2011; 44(12):4632-4640. · 5.93 Impact Factor
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    Georg M. Gübitz, Andreas Gronauer, Hans Oechsner
    Engineering in Life Sciences 12/2010; 10(6). · 1.63 Impact Factor
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    ABSTRACT: Ultrasound irradiation was applied as a "throwing stones" technique for coating cotton bandages with MgO and Al(2)O(3) commercially obtained nanoparticles. The homogeneous distribution of the nanoparticles without any aggregation on the fabrics was demonstrated. The antibacterial activities of the MgO/Al(2)O(3)-fabric nanocomposite were tested against Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive) cultures. A significant bactericidal effect, even in a concentration <1% (by weight), was detected.
    ACS Applied Materials & Interfaces 07/2010; 2(7):1999-2004. · 5.01 Impact Factor
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    ABSTRACT: Grafting natural antibacterial phenols onto lignocellulosic materials is an environmentally friendly way of imparting antibacterial properties to the substrates. In the present investigation, wood veneer and pulp were treated with tannins in the presence or absence of laccase. Treatments with hydrolysable tannins significantly improved the antibacterial resistance of veneers and paper made from tannin-treated pulp against a Gram-positive bacterium (Staphylococcus aureus) while a more modest protective effect was observed against a Gram-negative bacterium (Escherichia coli). Condensed tannin improved the antibacterial resistance against S. aureus, albeit less than hydrolysable tannin, but had little effect on E. coli. A cationic condensed tannin derivative bearing a quaternary amino group provided far better resistance to pulp against S. aureus and E. coli than the corresponding unmodified condensed tannin. These findings agree with the minimal inhibitory concentrations (MICs) of the tannins and their reactivities toward laccase as determined by O2 consumption measurements. Due to a better retention of tannins via covalent bonding, treatments with laccase usually resulted in greater antibacterial effects than those without laccase. LC–MS investigations with monomeric tannin and lignin model compounds showed that covalent bonding of tannin to lignin via radical coupling occurred in the presence of laccase.
    Process Biochemistry. 01/2010;
  • OESIB. Proceedings of the oxidative enzymes as sustainable industrial biocatalysts; 01/2010
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    ABSTRACT: A range of enteric polymeric molecules of different molecular masses and chemical structures were coupled to the protease Esperase (EC 3.4.21.62) using carbodiimide. The activities of the range of chemically modified enzymes of enlarged molecular weight were measured with a standard assay on casein as substrate. Gel filtration confirmed covalent bonding had taken place. Using the same activity value per gram of fibre, the range of modified enzymes were used to treat wool to see if the size of the enlarged enzyme would effect the location of enzyme attack and penetration ability. Less fibre damage in terms of weight loss and tensile strength of treated wool was observed for all six modified enzymes and was less than native enzyme of a similar activity level. All modified enzymes showed similar levels of improved shrink-resistance.
    Enzyme and Microbial Technology. 01/2010;
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    ABSTRACT: An insight into the progress made in applying heme peroxidases in grafting processes, starting from the production of simple resins to more complex polymers, is presented. The refinement of the different reaction conditions (solvents, concentrations of the reactants) and careful study of the reaction mechanisms have been instrumental in advancing enzymatic grafting processes. A number of processes described here show how peroxidase mediated catalysis could provide a new strategy as an alternative to conventional energy intensive procedures mediated by chemical catalysts.
    Biocatalysis Based on Heme Peroxidases, ISBN 978-3-642-12626-0. Springer-Verlag Berlin Heidelberg, 2010, p. 155. 01/2010;
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    ABSTRACT: Recent emerging studies on the grafting mechanisms of functional molecules onto complex lignocellulose moieties have shown useful insights and possibilities in opening new frontiers in the enzymatic development of multifunctional polymers. Thanks to these studies which have demonstrated in principle the ability of laccases to mediate the coupling of antimicrobial compounds, hydrophobic molecules, including application processes for the development of fibreboards, particle boards, laminates etc. Further, laccase mediated grafting strategies developed using small reactive molecules e.g. phenolic amines which impart reactive properties to an inert polymer demonstrates the remarkable opportunities of enzyme meditated functionalization of polymers. Therefore recent studies focusing on understanding the mechanistic basis of the coupling mechanisms in order to make meaningful contribution to the development of new processes and products are a welcome development.
    Biotechnology & genetic engineering reviews 01/2010; 27:305-30. · 1.31 Impact Factor
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    ABSTRACT: Biogas from agricultural biomass and residues is a valuable source of renewable energy. However, recalcitrant plant cell structures represent a barrier in the fermentative biodegradation process in single- and two-stage reactors. Therefore, approaches concerning a more efficient de-polymerisation of cellulose and hemicellulose to monomeric sugars are required amongst others in order to optimise the fermentation efficiency and to increase methane yields. Here we show a new strategy for the enhancement of biogas production from hemicellulose-rich substrates. Hemicellulolytic populations from a common biogas fermenter consortium were successively enriched in batch-cultures using a synthetic medium containing xylan powder as single carbon source under anaerobic mesophilic conditions. Enriched hemicellulolytic bacteria were immobilised on trace metal activated zeolite to ensure a stable storage and easy application. Xylanase activity increased continuously during subsequent enrichment cycles by up to 162%. In batch-culture experiments we were able to observe an increase of methane by 53% compared to controls without additionally introduced microorganisms immobilised on zeolite. Specific enrichment of hemicellulolytic bacteria during the process was confirmed by using single strand conformation polymorphism (SSCP) analysis based on amplification of the eubacterial 16S rDNA fragments. Using sequence analysis conspicuous bands from SSCP patterns could be identified as belonging to the groups Bacteroides sp., Azospira oryzae (Dechlorosoma sp.) as well as to a wide spectrum of diverse species within the order of Clostridiales (Firmicutes).
    Water Research 11/2009; 44(6):1970-80. · 4.66 Impact Factor
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    ABSTRACT: Conventional vat dyeing involves chemical reduction of dyes into their water-soluble leuco form generating considerable amounts of toxic chemicals in effluents. In the present study, a new beta-nicotinamide adenine dinucleotide disodium salt (NADH)-dependent reductase isolated from Bacillus subtilis was used to reduce the redox dyes CI Acid Blue 74, CI Natural Orange 6, and CI Vat Blue 1 into their water-soluble leuco form. Enzymatic reduction was optimized in relation to pH and temperature conditions. The reductase was able to reduce Acid Blue 74 and Natural Orange 6 in the presence of the stoichiometrically consumed cofactor NADH; meanwhile, Vat Blue 1 required the presence of mediator 1,8-dihydroxyanthraquinone. Oxygen from air was used to reoxidize the dyes into their initial forms. The enzymatic reduction of the dyes was studied and the kinetic constants determined, and these were compared to the chemically-reduced leuco form. The enzyme responsible for the reduction showed homology to a NADH-dependent reductase from B. subtilis based on results from the MS/MS peptide mass mapping of the tryptically digested protein. Additionally, the reduction of Acid Blue 74 to its leuco form by reductase from B. subtilis was confirmed using NADH regenerated by the oxidation of formic acid with formate dehydrogenase from Candida boidinii in the same solution.
    Applied Microbiology and Biotechnology 09/2009; 85(3):563-71. · 3.69 Impact Factor

Publication Stats

1k Citations
188.31 Total Impact Points

Institutions

  • 2013
    • Austrian Centre of Industrial Biotechnology
      Gratz, Styria, Austria
  • 1970–2013
    • Graz University of Technology
      • Institut für Umweltbiotechnologie
      Graz, Styria, Austria
  • 2009–2010
    • Bar Ilan University
      • Department of Chemistry
      Ramat Gan, Tel Aviv, Israel
  • 2008
    • University of Natural Resources and Life Science Vienna
      • Department für Lebensmittelwissenschaften und -technologie
      Vienna, Vienna, Austria
  • 2003–2007
    • University of Minho
      • Department of Biology
      Braga, Distrito de Braga, Portugal
  • 2004
    • Cologne University of Applied Sciences
      Köln, North Rhine-Westphalia, Germany
  • 1999
    • Karl-Franzens-Universität Graz
      Gratz, Styria, Austria
  • 1997–1998
    • University of British Columbia - Vancouver
      Vancouver, British Columbia, Canada