A membrane enzymatic reactor, consisting of a stirred tank coupled to an ultrafiltration membrane... more A membrane enzymatic reactor, consisting of a stirred tank coupled to an ultrafiltration membrane was set up for the enzymatic oxidation of xenobiotic compounds. The azo dye Orange II was selected for the model compound and manganese peroxidase for the oxidative enzyme. The ligninolytic cycle was initiated and maintained by the controlled addition of all factors (reactants, mediators, and stabilizers) at suitable rates. Considering the distinctiveness of this process, in which the substrate to be oxidized is not the primary substrate for the enzyme, a kinetic model was developed. The azo dye concentration and hydrogen peroxide addition rate were found to be the main factors affecting the process. The reaction kinetics was defined using a Michaelis-Menten model with respect to the Orange II concentration and a first-order linear dependence relative to the H(2)O(2) addition rate. The dynamic model, which takes into account both the kinetics and the hydraulics of the system, was validated by comparing the experimental results in continuous operation under steady and non-steady state to model predictions. In particular, the model predicted the behavior of the system when unexpected alterations in steady-state operation occurred. Furthermore, the model allowed us to obtain the most appropriate H(2)O(2)/Orange II ratio in the feed to maximize the process efficiency.
In the present work an enzymatic membrane reactor (EMR) for the oxidation of azo dyes by manganes... more In the present work an enzymatic membrane reactor (EMR) for the oxidation of azo dyes by manganese peroxidase (MnP) has been developed. The configuration consisted of a stirred tank reactor coupled with an ultrafiltration membrane. The membrane allowed for most of the enzymatic activity to be recovered while both the parent dye and the degradation products could pass through. Different operational strategies (batch, fed-batch, and continuous) and parameters such as enzyme activity, H 2 O 2 feeding rate, hydraulic retention time (in continuous operation), and dye loading rate were studied. At best conditions, a continuous operation with a dye decolorization higher than 85% and minimal enzymatic deactivation was feasible for 18 days, attaining an efficiency of 42.5 mg Orange II oxidized/MnP unit consumed.
The catalytic cycle of the enzyme manganese peroxidase (MnP) requires the presence of dicarboxyli... more The catalytic cycle of the enzyme manganese peroxidase (MnP) requires the presence of dicarboxylic acids to chelate and stabilize the oxidized and very unstable Mn 3+ , which is responsible for the final substrate oxidation. However, the enzymatic degradation of an azo dye, Orange II, was successfully performed in the absence of any carboxylic acid. To analyze this possible discrepancy, the effect of the presence of several organic acids (oxalic, malonic, tartaric and citric acids) was studied on the kinetics and the extension of the degradation of Orange II. The Mn 3+ chelating strength, an important factor that should influence the efficiency of the degradation, was determined for the different organic acids and the dye by cyclic voltammetry. Oxalic acid was determined to be the best chelator, followed by malonic, tartaric and finally, citric acid. Orange II was shown to act as a chelator, since the hydroxyl and sulfonic groups allow a stabilized complex to be formed, avoiding the use of any dicarboxylic acid. This distinctive property could be extended to other molecules with a potential binding capacity.
Anaerobic digestion (AD) has been shown to have the biological potential to decrease the concentr... more Anaerobic digestion (AD) has been shown to have the biological potential to decrease the concentrations of several organic micropollutants (OMPs) from sewage sludge. However, the mechanisms and factors behind these biotransformations, which are essential for elucidating the possible transformation products and to foster the complete removal of OMPs via operational strategies, remain unclear. Therefore, this study investigated the transformation mechanisms of 20 OMPs during the methanogenic step of AD with a focus on the role of acetate kinase (AK), which is a key enzyme in methane production. The results from lab-scale methanogenic reactors showed that this step accounts for much of the reported OMPs biotransformation in AD. Furthermore, enzymatic assays confirmed that AK transforms galaxolide, naproxen, nonylphenol, octylphenol, ibuprofen, diclofenac, bisphenol A and triclosan. Except for galaxolide, for which further studies are required to refine conclusions, the OMP's chemical structure was a determinant for the AK action because only compounds that contain a carboxyl or a hydroxyl group and that have a moderate steric hindrance were enzymatically transformed, likely by phosphorylation. For these 7 compounds, this enzymatic mechanism accounts for 10-90% of the measured methanogenic biotransformation, suggesting that other active enzymes of the AD process are also involved in OMPs biotransformation.
A membrane enzymatic reactor, consisting of a stirred tank coupled to an ultrafiltration membrane... more A membrane enzymatic reactor, consisting of a stirred tank coupled to an ultrafiltration membrane was set up for the enzymatic oxidation of xenobiotic compounds. The azo dye Orange II was selected for the model compound and manganese peroxidase for the oxidative enzyme. The ligninolytic cycle was initiated and maintained by the controlled addition of all factors (reactants, mediators, and stabilizers) at suitable rates. Considering the distinctiveness of this process, in which the substrate to be oxidized is not the primary substrate for the enzyme, a kinetic model was developed. The azo dye concentration and hydrogen peroxide addition rate were found to be the main factors affecting the process. The reaction kinetics was defined using a Michaelis-Menten model with respect to the Orange II concentration and a first-order linear dependence relative to the H(2)O(2) addition rate. The dynamic model, which takes into account both the kinetics and the hydraulics of the system, was validated by comparing the experimental results in continuous operation under steady and non-steady state to model predictions. In particular, the model predicted the behavior of the system when unexpected alterations in steady-state operation occurred. Furthermore, the model allowed us to obtain the most appropriate H(2)O(2)/Orange II ratio in the feed to maximize the process efficiency.
In the present work an enzymatic membrane reactor (EMR) for the oxidation of azo dyes by manganes... more In the present work an enzymatic membrane reactor (EMR) for the oxidation of azo dyes by manganese peroxidase (MnP) has been developed. The configuration consisted of a stirred tank reactor coupled with an ultrafiltration membrane. The membrane allowed for most of the enzymatic activity to be recovered while both the parent dye and the degradation products could pass through. Different operational strategies (batch, fed-batch, and continuous) and parameters such as enzyme activity, H 2 O 2 feeding rate, hydraulic retention time (in continuous operation), and dye loading rate were studied. At best conditions, a continuous operation with a dye decolorization higher than 85% and minimal enzymatic deactivation was feasible for 18 days, attaining an efficiency of 42.5 mg Orange II oxidized/MnP unit consumed.
Membrane bioreactors are being increasingly used in enzymatic catalysed transformations. However,... more Membrane bioreactors are being increasingly used in enzymatic catalysed transformations. However, the application of enzymatic-based treatment systems in the environmental field is rather unusual. The aim of this paper is to overview the application of enzymatic membrane reactors to wastewater treatment, more specifically to dye decolourisation. Firstly, the basic aspects such as different configurations of enzymatic reactors, advantages and disadvantages associated to their utilisation are revised as well as the application of this technology to wastewater treatment. Secondly, dye decolourisation by white-rot fungi and their oxidative enzymes are discussed, presenting an overall view from for in vivo and in vitro systems. Finally, dye decolourisation by manganese peroxidase in an enzymatic membrane reactor in continuous operation is presented.
The catalytic cycle of the enzyme manganese peroxidase (MnP) requires the presence of dicarboxyli... more The catalytic cycle of the enzyme manganese peroxidase (MnP) requires the presence of dicarboxylic acids to chelate and stabilize the oxidized and very unstable Mn 3+ , which is responsible for the final substrate oxidation. However, the enzymatic degradation of an azo dye, Orange II, was successfully performed in the absence of any carboxylic acid. To analyze this possible discrepancy, the effect of the presence of several organic acids (oxalic, malonic, tartaric and citric acids) was studied on the kinetics and the extension of the degradation of Orange II. The Mn 3+ chelating strength, an important factor that should influence the efficiency of the degradation, was determined for the different organic acids and the dye by cyclic voltammetry. Oxalic acid was determined to be the best chelator, followed by malonic, tartaric and finally, citric acid. Orange II was shown to act as a chelator, since the hydroxyl and sulfonic groups allow a stabilized complex to be formed, avoiding the use of any dicarboxylic acid. This distinctive property could be extended to other molecules with a potential binding capacity.
Membrane bioreactors are being increasingly used in enzymatic catalysed transformations. However,... more Membrane bioreactors are being increasingly used in enzymatic catalysed transformations. However, the application of enzymatic-based treatment systems in the environmental field is rather unusual. The aim of this paper is to overview the application of enzymatic membrane reactors to wastewater treatment, more specifically to dye decolourisation. Firstly, the basic aspects such as different configurations of enzymatic reactors, advantages and disadvantages associated to their utilisation are revised as well as the application of this technology to wastewater treatment. Secondly, dye decolourisation by white-rot fungi and their oxidative enzymes are discussed, presenting an overall view from for in vivo and in vitro systems. Finally, dye decolourisation by manganese peroxidase in an enzymatic membrane reactor in continuous operation is presented.
Abstract Many consumers are unable to enjoy the benefits of milk due to intolerance or even aller... more Abstract Many consumers are unable to enjoy the benefits of milk due to intolerance or even allergy to lactose. This inability to digest lactose is caused by a deficiency of the enzyme β-Galactosidase in the digestive tract, which performs the hydrolysis of lactose to form glucose and galactose, two sugars which are easily absorbed into the bloodstream. This study reports the Life Cycle Assessment (LCA) outcomes of the β-Galactosidase production in an industrial -scale facility from a cradle-to-gate perspective. Among the different alternatives of the production process of the β-Galactosidase enzyme, the use of recombinant Saccharomyces cerevisiae yeast expressing the lacA gene of Aspergillus niger was considered due to its higher production yield in comparison with wild strains. The primary source of environmental impact is the downstream processing related subsystem, specially attributed to the separation, concentration and purification of the enzyme as well as Cleaning-in-Place activities, required to maintain aseptic and sterile operational conditions. The use of alternative chemicals to the conventional ones in this latter stage could imply environmental improvements of the production process.
Abstract Many consumers are unable to enjoy the benefits of milk due to intolerance or even aller... more Abstract Many consumers are unable to enjoy the benefits of milk due to intolerance or even allergy to lactose. This inability to digest lactose is caused by a deficiency of the enzyme β-Galactosidase in the digestive tract, which performs the hydrolysis of lactose to form glucose and galactose, two sugars which are easily absorbed into the bloodstream. This study reports the Life Cycle Assessment (LCA) outcomes of the β-Galactosidase production in an industrial -scale facility from a cradle-to-gate perspective. Among the different alternatives of the production process of the β-Galactosidase enzyme, the use of recombinant Saccharomyces cerevisiae yeast expressing the lacA gene of Aspergillus niger was considered due to its higher production yield in comparison with wild strains. The primary source of environmental impact is the downstream processing related subsystem, specially attributed to the separation, concentration and purification of the enzyme as well as Cleaning-in-Place activities, required to maintain aseptic and sterile operational conditions. The use of alternative chemicals to the conventional ones in this latter stage could imply environmental improvements of the production process.
Journal of Industrial Microbiology & Biotechnology, Aug 1, 1999
Manganese peroxidase, MnP, is one of the major ligninolytic enzymes produced by a number of white... more Manganese peroxidase, MnP, is one of the major ligninolytic enzymes produced by a number of white-rot fungi. The ability of this enzyme to degrade lignin by the fungus Bjerkandera sp BOS55 has opened its application to related bioprocesses such as recalcitrant-compound degradation and effluent decolorization. The medium reported to induce MnP production is composed of chemical grade reagents, all with relatively high costs for application to detoxification purposes. The use of inexpensive sources for MnP production can bring its implementation closer. For this purpose, dairy residues from cheese processing were considered. MnP production obtained using crude whey as the sole substrate reached appreciable levels, around 190 U L -1 , values comparable to those found with synthetic media (between 175-250 U L -1 ). Thus, this cheese-processing byproduct can be used as an inexpensive alternative for the large-scale production of MnP.
Journal of Industrial Microbiology & Biotechnology, Aug 1, 1999
Manganese peroxidase, MnP, is one of the major ligninolytic enzymes produced by a number of white... more Manganese peroxidase, MnP, is one of the major ligninolytic enzymes produced by a number of white-rot fungi. The ability of this enzyme to degrade lignin by the fungus Bjerkandera sp BOS55 has opened its application to related bioprocesses such as recalcitrant-compound degradation and effluent decolorization. The medium reported to induce MnP production is composed of chemical grade reagents, all with relatively high costs for application to detoxification purposes. The use of inexpensive sources for MnP production can bring its implementation closer. For this purpose, dairy residues from cheese processing were considered. MnP production obtained using crude whey as the sole substrate reached appreciable levels, around 190 U L -1 , values comparable to those found with synthetic media (between 175-250 U L -1 ). Thus, this cheese-processing byproduct can be used as an inexpensive alternative for the large-scale production of MnP.
The white rot fungus Bjerkandera sp. strain BOS55 was shown in previous studies to cause high lev... more The white rot fungus Bjerkandera sp. strain BOS55 was shown in previous studies to cause high levels of kraft pulp bleaching and deligni®cation under culture conditions in which manganese peroxidase (MnP) occurs as the dominant oxidative enzyme. In this study, the MnP of Bjerkandera was isolated and tested in vitro with eucalyptus oxygen-deligni®ed kraft pulp (ODKP) based on measuring the reduction in kappa number as an indicator of lignin oxidation. The MnP preparation applied at 60 U/g pulp for 6 h caused a signi®cant decrease of 11±13% in the kappa number in the ODKP under optimal conditions compared to parallel-incubated controls lacking enzyme. The eects of MnP dosage, Mn 2 concentration, organic acid buer selection, pH and H 2 O 2 addition were evaluated. The optimal Mn 2 concentration range for lignin oxidation in ODKP was 100±500 lM. In the presence of low oxalate concentrations (0.3±2 mM), the Bjerkandera MnP also signi®cantly reduced the kappa number of ODKP by 6% without any Mn. This observation is in agreement with the fact that puri®ed Bjerkandera MnP has Mn-independent activities. Under incubation conditions with added Mn 2 , buers composed of metal-complexing organic acids provided two-fold better kappa number reductions compared to the inert acetic acid. The optimal H 2 O 2 dosage was found to be 0.017 lmol/min ml when added as semicontinuous pulses (every 30 min) or 0.2 lmol/min ml when generated continuously by glucose oxidase. Excess H 2 O 2 caused severe inactivation of MnP during the incubations. Factors that improved the turnover of the enzyme, such as Mn 2 and metal-chelating acids, stabilized MnP against rapid inactivation.
The bottleneck of the application of manganese peroxidase (MnP) on an industrial scale in pulp bi... more The bottleneck of the application of manganese peroxidase (MnP) on an industrial scale in pulp biobleaching or in degradation of hazardous compounds is the lack of an efficient production system. Three main problems arise for the continuous production of MnP during secondary metabolism of Phanerochaete chrysosporium: enzyme production occurs only under specific physiological conditions corresponding to C or N limitation, high O(2) tension, and adequate Mn(+2) concentration; the enzyme that is produced is destabilized by extracellular proteases; and excessive growth of the mycelium blocks effective oxygen transfer. To overcome these drawbacks, continuous production of MnP was optimized by selecting a suitable bioreactor configuration and the environmental and operating conditions affecting both enzyme production and stability. The combination between a proper feed rate and the application of a pulsation in a packed-bed bioreactor permitted the maintenance of continuous secretion of MnP while limiting mycelial growth and avoiding bed clogging. Environmental factors as an Mn(+2) concentration of 5000 microM and high oxygen tension enhanced MnP production. The hydraulics of the bioreactor corresponding to a plug flow model with partial mixing and an operating hydraulic rentention time of 24 h were optimal to achieve stable operating conditions. This policy allowed long operation periods, obtaining higher productivities than the best reported in the literature. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 130-137, 1997.
International Biodeterioration & Biodegradation, Jul 1, 2006
Single strains of nine white-rot fungal species were screened for the ability to degrade polycycl... more Single strains of nine white-rot fungal species were screened for the ability to degrade polycyclic aromatic hydrocarbons (PAHs) in forest and salt marsh soils. Of these, Bjerkandera adusta, Irpex lacteus and Lentinus tigrinus were outstanding PAH degraders in both saline and non-saline conditions. These three strains were tested in parallel to investigate the levels of salinity and PAH concentration which
The effect of the hydraulics, the oxygenation and the substrate composition on the production of ... more The effect of the hydraulics, the oxygenation and the substrate composition on the production of lignin peroxidase (LIP) by Phanerochaete chrysosporium immobilized in polyurethane foam in a packed bed bioreactor was studied. The hydrodynamic behaviour of the reactors was modified by selecting different flow recycling ratios (recycling flow/feeding flow), and therefore the flow model ranged from a complete mixed system
A membrane enzymatic reactor, consisting of a stirred tank coupled to an ultrafiltration membrane... more A membrane enzymatic reactor, consisting of a stirred tank coupled to an ultrafiltration membrane was set up for the enzymatic oxidation of xenobiotic compounds. The azo dye Orange II was selected for the model compound and manganese peroxidase for the oxidative enzyme. The ligninolytic cycle was initiated and maintained by the controlled addition of all factors (reactants, mediators, and stabilizers) at suitable rates. Considering the distinctiveness of this process, in which the substrate to be oxidized is not the primary substrate for the enzyme, a kinetic model was developed. The azo dye concentration and hydrogen peroxide addition rate were found to be the main factors affecting the process. The reaction kinetics was defined using a Michaelis-Menten model with respect to the Orange II concentration and a first-order linear dependence relative to the H(2)O(2) addition rate. The dynamic model, which takes into account both the kinetics and the hydraulics of the system, was validated by comparing the experimental results in continuous operation under steady and non-steady state to model predictions. In particular, the model predicted the behavior of the system when unexpected alterations in steady-state operation occurred. Furthermore, the model allowed us to obtain the most appropriate H(2)O(2)/Orange II ratio in the feed to maximize the process efficiency.
In the present work an enzymatic membrane reactor (EMR) for the oxidation of azo dyes by manganes... more In the present work an enzymatic membrane reactor (EMR) for the oxidation of azo dyes by manganese peroxidase (MnP) has been developed. The configuration consisted of a stirred tank reactor coupled with an ultrafiltration membrane. The membrane allowed for most of the enzymatic activity to be recovered while both the parent dye and the degradation products could pass through. Different operational strategies (batch, fed-batch, and continuous) and parameters such as enzyme activity, H 2 O 2 feeding rate, hydraulic retention time (in continuous operation), and dye loading rate were studied. At best conditions, a continuous operation with a dye decolorization higher than 85% and minimal enzymatic deactivation was feasible for 18 days, attaining an efficiency of 42.5 mg Orange II oxidized/MnP unit consumed.
The catalytic cycle of the enzyme manganese peroxidase (MnP) requires the presence of dicarboxyli... more The catalytic cycle of the enzyme manganese peroxidase (MnP) requires the presence of dicarboxylic acids to chelate and stabilize the oxidized and very unstable Mn 3+ , which is responsible for the final substrate oxidation. However, the enzymatic degradation of an azo dye, Orange II, was successfully performed in the absence of any carboxylic acid. To analyze this possible discrepancy, the effect of the presence of several organic acids (oxalic, malonic, tartaric and citric acids) was studied on the kinetics and the extension of the degradation of Orange II. The Mn 3+ chelating strength, an important factor that should influence the efficiency of the degradation, was determined for the different organic acids and the dye by cyclic voltammetry. Oxalic acid was determined to be the best chelator, followed by malonic, tartaric and finally, citric acid. Orange II was shown to act as a chelator, since the hydroxyl and sulfonic groups allow a stabilized complex to be formed, avoiding the use of any dicarboxylic acid. This distinctive property could be extended to other molecules with a potential binding capacity.
Anaerobic digestion (AD) has been shown to have the biological potential to decrease the concentr... more Anaerobic digestion (AD) has been shown to have the biological potential to decrease the concentrations of several organic micropollutants (OMPs) from sewage sludge. However, the mechanisms and factors behind these biotransformations, which are essential for elucidating the possible transformation products and to foster the complete removal of OMPs via operational strategies, remain unclear. Therefore, this study investigated the transformation mechanisms of 20 OMPs during the methanogenic step of AD with a focus on the role of acetate kinase (AK), which is a key enzyme in methane production. The results from lab-scale methanogenic reactors showed that this step accounts for much of the reported OMPs biotransformation in AD. Furthermore, enzymatic assays confirmed that AK transforms galaxolide, naproxen, nonylphenol, octylphenol, ibuprofen, diclofenac, bisphenol A and triclosan. Except for galaxolide, for which further studies are required to refine conclusions, the OMP's chemical structure was a determinant for the AK action because only compounds that contain a carboxyl or a hydroxyl group and that have a moderate steric hindrance were enzymatically transformed, likely by phosphorylation. For these 7 compounds, this enzymatic mechanism accounts for 10-90% of the measured methanogenic biotransformation, suggesting that other active enzymes of the AD process are also involved in OMPs biotransformation.
A membrane enzymatic reactor, consisting of a stirred tank coupled to an ultrafiltration membrane... more A membrane enzymatic reactor, consisting of a stirred tank coupled to an ultrafiltration membrane was set up for the enzymatic oxidation of xenobiotic compounds. The azo dye Orange II was selected for the model compound and manganese peroxidase for the oxidative enzyme. The ligninolytic cycle was initiated and maintained by the controlled addition of all factors (reactants, mediators, and stabilizers) at suitable rates. Considering the distinctiveness of this process, in which the substrate to be oxidized is not the primary substrate for the enzyme, a kinetic model was developed. The azo dye concentration and hydrogen peroxide addition rate were found to be the main factors affecting the process. The reaction kinetics was defined using a Michaelis-Menten model with respect to the Orange II concentration and a first-order linear dependence relative to the H(2)O(2) addition rate. The dynamic model, which takes into account both the kinetics and the hydraulics of the system, was validated by comparing the experimental results in continuous operation under steady and non-steady state to model predictions. In particular, the model predicted the behavior of the system when unexpected alterations in steady-state operation occurred. Furthermore, the model allowed us to obtain the most appropriate H(2)O(2)/Orange II ratio in the feed to maximize the process efficiency.
In the present work an enzymatic membrane reactor (EMR) for the oxidation of azo dyes by manganes... more In the present work an enzymatic membrane reactor (EMR) for the oxidation of azo dyes by manganese peroxidase (MnP) has been developed. The configuration consisted of a stirred tank reactor coupled with an ultrafiltration membrane. The membrane allowed for most of the enzymatic activity to be recovered while both the parent dye and the degradation products could pass through. Different operational strategies (batch, fed-batch, and continuous) and parameters such as enzyme activity, H 2 O 2 feeding rate, hydraulic retention time (in continuous operation), and dye loading rate were studied. At best conditions, a continuous operation with a dye decolorization higher than 85% and minimal enzymatic deactivation was feasible for 18 days, attaining an efficiency of 42.5 mg Orange II oxidized/MnP unit consumed.
Membrane bioreactors are being increasingly used in enzymatic catalysed transformations. However,... more Membrane bioreactors are being increasingly used in enzymatic catalysed transformations. However, the application of enzymatic-based treatment systems in the environmental field is rather unusual. The aim of this paper is to overview the application of enzymatic membrane reactors to wastewater treatment, more specifically to dye decolourisation. Firstly, the basic aspects such as different configurations of enzymatic reactors, advantages and disadvantages associated to their utilisation are revised as well as the application of this technology to wastewater treatment. Secondly, dye decolourisation by white-rot fungi and their oxidative enzymes are discussed, presenting an overall view from for in vivo and in vitro systems. Finally, dye decolourisation by manganese peroxidase in an enzymatic membrane reactor in continuous operation is presented.
The catalytic cycle of the enzyme manganese peroxidase (MnP) requires the presence of dicarboxyli... more The catalytic cycle of the enzyme manganese peroxidase (MnP) requires the presence of dicarboxylic acids to chelate and stabilize the oxidized and very unstable Mn 3+ , which is responsible for the final substrate oxidation. However, the enzymatic degradation of an azo dye, Orange II, was successfully performed in the absence of any carboxylic acid. To analyze this possible discrepancy, the effect of the presence of several organic acids (oxalic, malonic, tartaric and citric acids) was studied on the kinetics and the extension of the degradation of Orange II. The Mn 3+ chelating strength, an important factor that should influence the efficiency of the degradation, was determined for the different organic acids and the dye by cyclic voltammetry. Oxalic acid was determined to be the best chelator, followed by malonic, tartaric and finally, citric acid. Orange II was shown to act as a chelator, since the hydroxyl and sulfonic groups allow a stabilized complex to be formed, avoiding the use of any dicarboxylic acid. This distinctive property could be extended to other molecules with a potential binding capacity.
Membrane bioreactors are being increasingly used in enzymatic catalysed transformations. However,... more Membrane bioreactors are being increasingly used in enzymatic catalysed transformations. However, the application of enzymatic-based treatment systems in the environmental field is rather unusual. The aim of this paper is to overview the application of enzymatic membrane reactors to wastewater treatment, more specifically to dye decolourisation. Firstly, the basic aspects such as different configurations of enzymatic reactors, advantages and disadvantages associated to their utilisation are revised as well as the application of this technology to wastewater treatment. Secondly, dye decolourisation by white-rot fungi and their oxidative enzymes are discussed, presenting an overall view from for in vivo and in vitro systems. Finally, dye decolourisation by manganese peroxidase in an enzymatic membrane reactor in continuous operation is presented.
Abstract Many consumers are unable to enjoy the benefits of milk due to intolerance or even aller... more Abstract Many consumers are unable to enjoy the benefits of milk due to intolerance or even allergy to lactose. This inability to digest lactose is caused by a deficiency of the enzyme β-Galactosidase in the digestive tract, which performs the hydrolysis of lactose to form glucose and galactose, two sugars which are easily absorbed into the bloodstream. This study reports the Life Cycle Assessment (LCA) outcomes of the β-Galactosidase production in an industrial -scale facility from a cradle-to-gate perspective. Among the different alternatives of the production process of the β-Galactosidase enzyme, the use of recombinant Saccharomyces cerevisiae yeast expressing the lacA gene of Aspergillus niger was considered due to its higher production yield in comparison with wild strains. The primary source of environmental impact is the downstream processing related subsystem, specially attributed to the separation, concentration and purification of the enzyme as well as Cleaning-in-Place activities, required to maintain aseptic and sterile operational conditions. The use of alternative chemicals to the conventional ones in this latter stage could imply environmental improvements of the production process.
Abstract Many consumers are unable to enjoy the benefits of milk due to intolerance or even aller... more Abstract Many consumers are unable to enjoy the benefits of milk due to intolerance or even allergy to lactose. This inability to digest lactose is caused by a deficiency of the enzyme β-Galactosidase in the digestive tract, which performs the hydrolysis of lactose to form glucose and galactose, two sugars which are easily absorbed into the bloodstream. This study reports the Life Cycle Assessment (LCA) outcomes of the β-Galactosidase production in an industrial -scale facility from a cradle-to-gate perspective. Among the different alternatives of the production process of the β-Galactosidase enzyme, the use of recombinant Saccharomyces cerevisiae yeast expressing the lacA gene of Aspergillus niger was considered due to its higher production yield in comparison with wild strains. The primary source of environmental impact is the downstream processing related subsystem, specially attributed to the separation, concentration and purification of the enzyme as well as Cleaning-in-Place activities, required to maintain aseptic and sterile operational conditions. The use of alternative chemicals to the conventional ones in this latter stage could imply environmental improvements of the production process.
Journal of Industrial Microbiology & Biotechnology, Aug 1, 1999
Manganese peroxidase, MnP, is one of the major ligninolytic enzymes produced by a number of white... more Manganese peroxidase, MnP, is one of the major ligninolytic enzymes produced by a number of white-rot fungi. The ability of this enzyme to degrade lignin by the fungus Bjerkandera sp BOS55 has opened its application to related bioprocesses such as recalcitrant-compound degradation and effluent decolorization. The medium reported to induce MnP production is composed of chemical grade reagents, all with relatively high costs for application to detoxification purposes. The use of inexpensive sources for MnP production can bring its implementation closer. For this purpose, dairy residues from cheese processing were considered. MnP production obtained using crude whey as the sole substrate reached appreciable levels, around 190 U L -1 , values comparable to those found with synthetic media (between 175-250 U L -1 ). Thus, this cheese-processing byproduct can be used as an inexpensive alternative for the large-scale production of MnP.
Journal of Industrial Microbiology & Biotechnology, Aug 1, 1999
Manganese peroxidase, MnP, is one of the major ligninolytic enzymes produced by a number of white... more Manganese peroxidase, MnP, is one of the major ligninolytic enzymes produced by a number of white-rot fungi. The ability of this enzyme to degrade lignin by the fungus Bjerkandera sp BOS55 has opened its application to related bioprocesses such as recalcitrant-compound degradation and effluent decolorization. The medium reported to induce MnP production is composed of chemical grade reagents, all with relatively high costs for application to detoxification purposes. The use of inexpensive sources for MnP production can bring its implementation closer. For this purpose, dairy residues from cheese processing were considered. MnP production obtained using crude whey as the sole substrate reached appreciable levels, around 190 U L -1 , values comparable to those found with synthetic media (between 175-250 U L -1 ). Thus, this cheese-processing byproduct can be used as an inexpensive alternative for the large-scale production of MnP.
The white rot fungus Bjerkandera sp. strain BOS55 was shown in previous studies to cause high lev... more The white rot fungus Bjerkandera sp. strain BOS55 was shown in previous studies to cause high levels of kraft pulp bleaching and deligni®cation under culture conditions in which manganese peroxidase (MnP) occurs as the dominant oxidative enzyme. In this study, the MnP of Bjerkandera was isolated and tested in vitro with eucalyptus oxygen-deligni®ed kraft pulp (ODKP) based on measuring the reduction in kappa number as an indicator of lignin oxidation. The MnP preparation applied at 60 U/g pulp for 6 h caused a signi®cant decrease of 11±13% in the kappa number in the ODKP under optimal conditions compared to parallel-incubated controls lacking enzyme. The eects of MnP dosage, Mn 2 concentration, organic acid buer selection, pH and H 2 O 2 addition were evaluated. The optimal Mn 2 concentration range for lignin oxidation in ODKP was 100±500 lM. In the presence of low oxalate concentrations (0.3±2 mM), the Bjerkandera MnP also signi®cantly reduced the kappa number of ODKP by 6% without any Mn. This observation is in agreement with the fact that puri®ed Bjerkandera MnP has Mn-independent activities. Under incubation conditions with added Mn 2 , buers composed of metal-complexing organic acids provided two-fold better kappa number reductions compared to the inert acetic acid. The optimal H 2 O 2 dosage was found to be 0.017 lmol/min ml when added as semicontinuous pulses (every 30 min) or 0.2 lmol/min ml when generated continuously by glucose oxidase. Excess H 2 O 2 caused severe inactivation of MnP during the incubations. Factors that improved the turnover of the enzyme, such as Mn 2 and metal-chelating acids, stabilized MnP against rapid inactivation.
The bottleneck of the application of manganese peroxidase (MnP) on an industrial scale in pulp bi... more The bottleneck of the application of manganese peroxidase (MnP) on an industrial scale in pulp biobleaching or in degradation of hazardous compounds is the lack of an efficient production system. Three main problems arise for the continuous production of MnP during secondary metabolism of Phanerochaete chrysosporium: enzyme production occurs only under specific physiological conditions corresponding to C or N limitation, high O(2) tension, and adequate Mn(+2) concentration; the enzyme that is produced is destabilized by extracellular proteases; and excessive growth of the mycelium blocks effective oxygen transfer. To overcome these drawbacks, continuous production of MnP was optimized by selecting a suitable bioreactor configuration and the environmental and operating conditions affecting both enzyme production and stability. The combination between a proper feed rate and the application of a pulsation in a packed-bed bioreactor permitted the maintenance of continuous secretion of MnP while limiting mycelial growth and avoiding bed clogging. Environmental factors as an Mn(+2) concentration of 5000 microM and high oxygen tension enhanced MnP production. The hydraulics of the bioreactor corresponding to a plug flow model with partial mixing and an operating hydraulic rentention time of 24 h were optimal to achieve stable operating conditions. This policy allowed long operation periods, obtaining higher productivities than the best reported in the literature. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 130-137, 1997.
International Biodeterioration & Biodegradation, Jul 1, 2006
Single strains of nine white-rot fungal species were screened for the ability to degrade polycycl... more Single strains of nine white-rot fungal species were screened for the ability to degrade polycyclic aromatic hydrocarbons (PAHs) in forest and salt marsh soils. Of these, Bjerkandera adusta, Irpex lacteus and Lentinus tigrinus were outstanding PAH degraders in both saline and non-saline conditions. These three strains were tested in parallel to investigate the levels of salinity and PAH concentration which
The effect of the hydraulics, the oxygenation and the substrate composition on the production of ... more The effect of the hydraulics, the oxygenation and the substrate composition on the production of lignin peroxidase (LIP) by Phanerochaete chrysosporium immobilized in polyurethane foam in a packed bed bioreactor was studied. The hydrodynamic behaviour of the reactors was modified by selecting different flow recycling ratios (recycling flow/feeding flow), and therefore the flow model ranged from a complete mixed system
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