Ana M R B Xavier

Ana M R B Xavier
University of Aveiro | UA · CICECO - Centre for Research in Ceramics and Composite Materials

PhD in Biological Engineering - Microbial technolo

About

65
Publications
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Introduction
PhD in Biological Engineering - Microbial Technology in Universidade Nova de Lisboa, 1996. Assistant Professor in Chemical Dep. of Universidade de Aveiro. Scientific interests and specialization on Lignocellulosics for bioprocesses. Ligninolytic activity for bleaching processes of pulp and paper industry. Ligninolytic activity for pulp and paper effluent cleaning processes. Bioethanol production from lignocellulosic biomass. Different lignocelulosic biomass pre-treatments, hydrolysis and fermentation. Laccase production and induction. Laccase immobilization in nanoparticles and laccase activation with ionic liquids. Biorefinery - Potentialities of hardwood spent sulfite liquor. Yeasts for bioethanol production, Single Cell Protein and biopolymers production. Mixed cultures for subproducts
Additional affiliations
February 2003 - present
University of Aveiro
Position
  • Professor (Assistant)
November 1985 - October 1987
Universidade NOVA de Lisboa
Position
  • Monitor of practical classes

Publications

Publications (65)
Article
An approach for the integrated utilization of grape skins from white grape pomaces has been proposed. This consists of consecutive or simultaneous extraction of grape skins with neutral organic solvent and water under reflux. Organic extract is a valuable raw material for the isolation of oleanolic acid. The aqueous extract (ca 50%, w/w) is compose...
Article
Full-text available
The pulp and paper industry is recognized as a well-established sector, which throughout its process, generates a vast amount of waste streams with the capacity to be valorized. Typically, these residues are burned for energy purposes, but their use as substrates for biological processes could be a more efficient and sustainable alternative. With t...
Chapter
Currently, the world is facing an energy transition, with governments pushing for a switch from fossil to bio-based fuels. The transport sector is responsible for about 30% of the European energy consumption, which is still mainly obtained from burning fossil fuels, accounting for 25% of the greenhouse gas emissions. Consequently, the European Unio...
Article
Full-text available
The pulp and paper industry faces an emerging challenge for valorising wastes and side-streams generated according to the biorefinery concept. Eucalyptus globulus bark, an abundant industrial residue in the Portuguese pulp and paper sector, has a high potential to be converted into biobased products instead of being burned. This work aimed to evalu...
Article
Full-text available
Second-generation bioethanol production’s main bottleneck is the need for a costly and technically difficult pretreatment due to the recalcitrance of lignocellulosic biomass (LCB). Chemical pulping can be considered as a LCB pretreatment since it removes lignin and targets hemicelluloses to some extent. Chemical pulps could be used to produce ethan...
Article
Full-text available
Due to the health and environment impacts of fossil fuels utilization, biofuels have been investigated as a potential alternative renewable source of energy. Bioethanol is currently the most produced biofuel, mainly of first generation, resulting in food-fuel competition. Second generation bioethanol is produced from lignocellulosic biomass, but a...
Article
Full-text available
Hardwood spent sulfite liquor (HSSL) is a by-product from pulp industry with a high concentration of pentose sugars, besides some hexoses suitable for bioethanol production by Scheffersomyces stipitis. The establishment of optimal aeration process conditions that results in specific microaerophilic conditions required by S. stipitis is the main cha...
Article
Due to the health and environment impacts of fossil fuels utilization, biofuels have been investigated as a potential alternative renewable source of energy. Bioethanol is currently the most produced biofuel, mainly of first generation, resulting in food-fuel competition. Second generation bioethanol is produced from lignocellulosic biomass, but a...
Article
Magnetic materials can be easily separated from reaction media by application of an external magnetic field. On the other hand, nanomaterials are innovative platforms which present high surface-to-volume ratio allowing low mass transfer limitations. Magnetic nanoparticles (MNPs) can be considered as supports for catalysts immobilization since they...
Chapter
The developments of laccase enzymes (benzenediol:oxygen oxidoreductase, EC 1.10.3.2) in industrial applications and investigation are revised in this chapter. Laccases are considered as “green biocatalysts” and versatile enzymes for emerging biotechnological applications. Highlighting the key aspects and recent advances in biocatalysis, this book c...
Article
Developments in nanotechnology have led to the discovery of new materials, namely, magnetic nanoparticles (MNPs), that present easy surface functionalization and high surface-to-volume ratios. These properties allow a high mass transfer rate and easy removal from a reaction matrix. Simple separation under an external magnetic field makes them a pro...
Article
Full-text available
Hardwood spent sulfite liquor (HSSL) is a by-product from pulping industry with huge potential for second generation bioethanol production, owing to its high sugars content, namely xylose and glucose. Scheffersomyces stipitis can use this substrate since it is able to ferment either hexoses or pentoses. Nevertheless, this yeast requires microaeroph...
Poster
Full-text available
Hardwood spent sulfite liquor (HSSL) is a by-product from pulping industry with huge potential for second generation bioethanol production, owing to its high sugars content, namely xylose and glucose. Scheffersomyces stipitis can use this substrate since it is able to ferment either hexoses or pentoses. Nevertheless, this yeast requires microaeroph...
Article
Magnetic materials can be easily separated from reaction media by application of an external magnetic field. On the other hand, nanomaterials are innovative platforms which present high surface-to-volume ratio allowing low mass transfer limitations. Magnetic nanoparticles (MNPs) can be considered as supports for catalysts immobilization since they...
Article
Abstract: Background: Basidiomycete Trametes versicolor is one of the most studied white rot fungus due to its great genetic potential responsible for the expression of different and powerful capacities such as degrading lignocellulose in wood decay bioprocesses. T. versicolor whole genome is currently being sequenced due to the high interest in us...
Article
Full-text available
Hardwood spent sulfite liquor (HSSL) is a by-product of acid sulfite pulping process that is rich in xylose, a monosaccharide that can be fermented to ethanol by Scheffersomyces stipitis. However, HSSL also contains acetic acid and lignosulfonates that are inhibitory compounds of yeast growth. The main objective of this study was the use of an evol...
Poster
Full-text available
Bioethanol can be blended with the gasoline allowing the reduction of petroleum consumption, as well as the greenhouse gases emissions. However, the first generation bioethanol, produced from food feedstocks, triggered serious social problems, therefore the second generation bioethanol, produced from lignocellulosic biomass, becomes an attractive a...
Article
Full-text available
A wide range of value-added products can potentially be produced by bioprocessing hardwood spent sulfite liquors (HSSLs) that are by-products of pulp and paper industry with a high pentose sugar content. However, besides sugars, HSSLs contain considerable amounts of sulfonated lignin derivatives and acetic acid that inhibit the metabolic activity o...
Article
The correct choice of the specific lignocellulosic biomass pretreatment allows obtaining high biomass conversions for biorefinery implementations and cellulosic bioethanol production from renewable resources. Cynara cardunculus (cardoon) pretreated by steam explosion (SE) was involved in second-generation bioethanol production using separate hydrol...
Conference Paper
Full-text available
This work shows that acidic sulphite pulp industries could use the fungus Paecilomyces variotii in a biorefinery concept to valorise hardwood spent sulphite liquor (HSSL), in order to produce bioethanol after the single-cell protein (SCP) production, and thus improving their sustainability. P. variotii was able to use inhibitory compounds present i...
Article
Bacterial cellulose (BC) has attracted attention as a new functional material due to its excellent mechanical strength, tridimensional nanostructure, high purity, and increased water absorption, compared to plant cellulose. In this work, commercial laccase was immobilized on BC and the influence of enzyme concentration, contact time and pH was opti...
Chapter
Full-text available
In this book chapter the information available on biotechnology applications in the pulp and paper industry has been reviewed. The chapter is divided in the following interlinked sections: (1) general introduction; (2) brief description of pulp and paper process; (3) biotechnology applications in wood pulping; (4) enzymatic catalysis in pulp bleach...
Chapter
Full-text available
This chapter presents an overview of oxidative enzymes and their developments in applications for degradation of different industrial effluents. An increasing number of oxidative biocatalysis has been reported during the last years, which indicates the wide variability and potential of these biocatalysts. The first part of this chapter describes th...
Article
Full-text available
Image analysis technique was applied to identify morphological changes of pellets from white-rot fungus Trametes versicolor on agitated submerged cultures during the production of exopolysaccharide (EPS) or ligninolytic enzymes. Batch tests with four different experimental conditions were carried out. Two different culture media were used, namely y...
Poster
Full-text available
Hardwood Spent Sulphite Liquor (HSSL) is a by-product from acidic sulphite pulping of wood, rich in pentoses, which can be fermented by the yeast Scheffersomyces stipitis to produce second generation bioethanol. Unlike Saccharomyces cerevisiae, S. stipitis had the advantage of fermenting both hexoses and pentoses. However, S. stipitis is quite sens...
Article
Sulphite spent liquor (SSL) is a side product from acidic sulphite pulping of wood, which organic counterpart is composed mainly by lignosulphonates (LS) and sugars. The last are a prominent substrate for the bioprocessing although a previous purification step is necessary to eliminate microbial inhibitors. In this study a fractionation of hardwood...
Article
The stability and activity of laccase from Trametes versicolor in two water-soluble ionic liquids (ILs), namely 1-butyl-3-methylimidazolium methyl sulfate, [bmim][MeSO4] and 1,3-dimethylimidazolium methyl sulfate, [mmim][MeSO4], were investigated in this study. Thermal inactivation of laccase was characterized in the presence of these both ILs and...
Article
Full-text available
Laccase production from Trametes versicolor was improved in the presence of the inducers ligninosulphonates, veratryl alcohol, and xylidine respectively two-, four-, and eightfold. The thermal inactivation of the produced laccase, after partial purification with ammonium sulfate was kinetically investigated at various temperatures (60-70 °C) and pH...
Article
The fermentation of reducing sugars from hardwood (eucalypt) spent sulphite liquor (HSSL) into ethanol by Pichia (Scheffersomyces) stipitis is hindered by concomitant inhibitors of microbial metabolism. The conditions for the HSSL biological treatment step by Paecilomyces variotii were evaluated and optimised. Two different strategies of reactor op...
Article
Maloalcoholic fermentation (MAF) of grape must by Schizosaccharomyces pombe immobilised in calcium-alginate double-layer beads (ProMalic®) was studied in Erlenmeyer flasks and in a total recycle fixed-bed reactor operating in batch mode. The reaction is pseudo-first order with respect to l-malic acid and under similar conditions deacidification is...
Article
The spent liquor from acidic sulphite pulping of Eucalyptus globulus (HSSL) is the side product from sulphite pulp production and besides sulphonated lignin contains sugars from degraded hemicelluloses, mainly pentoses. Pichia stipitis fermentation of these sugars for bioethanol production was the primary goal of this work. The increasing of HSSL p...
Article
BACKGROUND: A sequential batch reactor (SBR) was used for eucalypt kraft pulp effluent treatment with Trametes versicolor. A 23 full factorial design and response surface methodology were applied to optimise the batch fermentation conditions. Effluent concentration, culture medium and inoculum age were the factors selected for this study in order t...
Conference Paper
The metabolic behaviour of white rot fungus Trametes versicolor was studied on agitated submerged cultures in its ability to produce exopolysaccharides and ligninolytic enzymes. With that purpose, batch tests with four different experimental conditions were performed. Two different culture media were used namely Yeast Malt Extract Medium (Kim et al...
Article
Experimental work on ultrafiltration is presented to illustrate the practical and theoretical principles of this separation technique. The laboratory exercise comprises experiments with pure water and with aqueous Saccharomyces cerevisiae (from commercial Baker's yeast) suspensions. With this work students detect the characteristic phenomena involv...
Article
Full-text available
The cultivation of Trametes versicolor for laccase production and cell growth were strongly dependent on experimental conditions namely physical and chemical parameters as well as nutrient availability and inducer stimulation. Biomass growth was compared for a rich medium and for a defined medium in two different temperatures. The best temperature...
Article
The cultivation of Trametes versicolor for laccase production and cell growth were strongly dependent on experimental conditions namely physical and chemical parameters as well as nutrient availability and inducer stimulation. Biomass growth was compared for a rich medium and for a defined medium in two different temperatures. The best temperature...
Article
New polyoxometalate–laccase integrated system (PLIDS) employing polyoxometalate [SiW11VVO40]5− and laccase of Trametes versicolor for the continuous delignification of eucalypt kraft pulp has been developed. Pulp was delignified in a batch reactor containing catalytic amounts of [SiW11VVO40]5− at about 90 °C under atmospheric pressure. Re-oxidation...
Article
Full-text available
Experimental design and response surface methodologies were applied to optimize laccase production by Trametes versicolor in a bioreactor. The effects of three factors, initial glucose concentration (0 and 9 g/L), agitation (100 and 180 rpm), and pH (3.0 and 5.0), were evaluated to identify the significant effects and its interactions in the laccas...
Article
Full-text available
Coriolus versicolor is a medicinal fungus producing exopolysaccharides (EPS). Five well-defined culture media were studied to select the medium that maximizes production of EPS by C. versicolor. Biomass, reducing sugars and EPS concentrations along with the rheological behaviour of the broth were followed during fermentations lasting 9days. The yea...
Article
A series of manganese substituted polyoxotungstates, [SiW11MnIII(H2O)O39]5− and [PW11MnIII(H2O)O39]4−, and [SiW11VVO40]5− were applied as catalysts for the oxygen delignification of unbleached eucalypt kraft pulp with laccase of Trametes versicolor. Unlike to modest results obtained in the Laccase-Mediator System (LMS) at 45–60 °C (lignin oxidation...
Article
Improvement of laccase production by Trametes versicolor was made by employing different operational strategies. In the cell growth medium, various glucose concentrations were compared for improving laccase production. A clear and significant stimulation of enzyme production under carbon limitation was obtained. Copper, 2,5-xylidine, and a phenolic...
Article
A simple procedure to study adsorption principles is presented. The solid–liquid system consists of glass microspheres and aqueous solutions of an organic dye, Crystal Violet. With this experiment students determine an adsorption isotherm and analyze the dynamic behavior of a percolation column, carrying out a breakthrough experiment in a laborator...
Article
Full-text available
The white rot fungus Trametes versicolor was applied to the decolourisation of three synthetic textile dyes in the presence and absence of glucose. Different initial dye concentrations were tested and approximately 97% decolourisation was achieved. It was found that fungal metabolism induced by the glucose as well as the pH play an important role i...
Article
A novel approach for the catalytic oxygen bleaching of kraft pulp using the heteropolyanion [SiW11MnIII(H2O)O39]5− (SiW11MnIII) and laccase of Trametes versicolor is proposed. The oxidation of the residual lignin in pulp with the heteropolyanion was followed by the catalyst re-oxidation by laccase in a separate stage. The alterative treatment in a...
Article
A series of phenolic/non-phenolic biphenyl model compounds mimicking 5-5′ type “condensed” lignin substructures were subjected to the oxidation with laccase of Trametes versicolor in the presence of 1-hydroxybenzotriazole (HBT) or [SiW11VO40]5− (SiW11V) as mediators. Phenolic models suffered a significant degradation in both the laccase-mediator sy...
Article
Mechanical stress due to micro/ultrafiltration has been suggested by a number of authors as one of the sources for cell deactivation in continuous cell-recycle reactors. This work introduces cell deactivation in the modelling of cell-recycle fermenters. A two-population based model is used. It is shown that the kinetic parameters obtained from chem...
Article
Batch cultures of Lactobacillus rhamnosus were carried out at different pH values in order to study the limitation of growth and lactic acid production by the hydrogen ion, non-dissociated lactic acid and internal lactate concentrations. The effect of pH between 5 and 6.8 was studied at non-limiting concentrations of glucose; this is more significa...
Article
Fermentation with complete cell recycle on microfiltration tubular membranes was studied and its effect upon broth rheology evaluated. The increase in cell concentration was found to be responsible for a continuous rise in viscosity leading to changes of broth rheology and consequent operating problems. A strategy to control the broth rheological b...
Article
Lactic acid production with cell recycling on an ultrafiltration tubular membrane reactor was studied; higher lactic acid concentrations as well as productivities were obtained under long-term fermentations compared with other high cell density systems. Different operational conditions, namely dilution rates and start-up modes, were assessed. Perfo...
Article
The operation of cell recycle systems by membrane filtration is discussed, stressing the importance of the mutual interaction between the biological and the physical characteristics of the fermentation process. Broth circulation flow rate, dilution rate, and cell bleed rate are identified as being the most important process variables. Their effects...
Article
Full-text available
Production of lactic acid using Lactobacillus delbrueckii NRRL B445 recently renamed L. rhamnosus was studied in continuously recycled packed reactors at pH 6.3 and 42 C. Four inert adsorbent supports were used for immobilization: Raschig rings of sintered glass (Schott, FRG), beads of sintered glass (Schott), beads of porous glass (Poraver; Denner...
Article
The influence of glucose inhibition on growth and lactic acid production kinetics of Lactobacillus delbrueckii NRRL B445 was studied in batch cultures. Continuous experiments (CSTR) were also carried out. A model for substrate consumption, cell growth, and lactic acid production considering both substrate and product inhibition is proposed; this mo...
Article
A simple method of assessing the viability of a lactic starter culture is presented. The method is based on the kinetics of growth of a culture during the lag and early exponential phases. The microorganisms used throughout this work were Lactobacillus spp. The method was tested with inocula samples of different ages and with samples taken during c...
Article
Full-text available
The capacity of white-rot fungi Trametes versicolor, to reduce the chemical oxygen demand (COD) and to decolourise the effluent of the paper industry Portucel, Empresa de Celulose e Papel de Portugal, SA, Cacia, was studied. The fermentation was carried out with T. versicolor on Trametes Defined Medium diluted in the industrial effluent. The lignin...
Article
Full-text available
Environmental pressure has led pulp and paper industry to develop new technologies for reducing pollutants in bleaching plant effluents. One chance for this purpose is using enzyme-based biotechnology processes for catalytic functions. The oxygen delignification catalysed by polyoxometalates (POM) is considered as a new perspective in pulp bleachin...

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Projects (6)
Project
The main rationale of this project is thus to develop novel membranes consisting of polymer sub-micro fiber arrays combining high separation performance, adsorption and catalytic properties, and capacity to remove selected mycotoxins, involving simple filtration steps and avoiding lost of nutritive and/or organoleptic attributes.