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Xylooligosaccharides (XOS) are nondigestible compounds of great interest for food and pharmaceutical industries due to their beneficial prebiotic, antibacterial, antioxidant, and antitumor properties. The market size of XOS is increasing significantly, which makes its production from lignocellulosic biomass an interesting approach to the valorization of the hemicellulose fraction of biomass, which is currently underused. This review comprehensively discusses XOS production from lignocellulosic biomass, aiming at its application in integrated biorefineries. A bibliometric analysis is carried out highlighting the main players in the field. XOS production yields after different biomass pretreatment methods are critically discussed using Microsoft PowerBI® (2.92.706.0) software, which involves screening important trends for decision-making. Enzymatic hydrolysis and the major XOS purification strategies are also explored. Finally, the integration of XOS production into biorefineries, with special attention to economic and environmental aspects, is assessed, providing important information for the implementation of biorefineries containing XOS in their portfolio.
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In this study, soybean oil deodorizer distillate (SODD), a mixture of free fatty acids and acylglycerides, and isoamyl alcohol were evaluated as substrates in the synthesis of fatty acid isoamyl monoesters catalyzed by Eversa (a liquid formulation of Thermomyces lanuginosus lipase). SODD and the products were characterized by the chemical and physical properties of lubricant base stocks. The optimal conditions to produce isoamyl fatty acid esters were determined by response surface methodology (RSM) using rotational central composite design (RCCD, 23 factorial + 6 axial points + 5 replications at the central point); they were 1 mol of fatty acids (based on the SODD saponifiable index) to 2.5 mol isoamyl alcohol, 45 °C, and 6 wt.% enzymes (enzyme mass/SODD mass). The effect of the water content of the reactional medium was also studied, with two conditions of molecular sieve ratio (molecular sieve mass/SODD mass) selected as 39 wt.% (almost anhydrous reaction medium) and 9 wt.%. Ester yields of around 50 wt.% and 70 wt.% were reached after 50 h reaction, respectively. The reaction products containing 43.7 wt.% and 55.2 wt.% FAIE exhibited viscosity indices of 175 and 163.8, pour points of -6 °C and -9 °C, flash points of 178 and 104 °C, and low oxidative stability, respectively. Their properties (mainly very high viscosity indices) make them suitable to be used as base stocks in lubricant formulation industries.
Assuntos
Lubrificantes , Óleo de Soja , Esterificação , Ácidos Graxos/química , Lipase/química , Óleo de Soja/químicaRESUMO
Attainment of a stable and highly active ß-xylosidase is of major importance for the efficient and cost-competitive hydrolysis of hemicellulose xylan, as well as for its industrial conversion into biofuels and biochemicals. Here, a recombinant ß-xylosidase of the glycoside hydrolase family (GH43) from Bacillus subtilis was produced in Escherichia coli culture, purified, and subsequently immobilized on agarose and chitosan. Glutaraldehyde and glyoxyl groups were evaluated as activating agents to select the most efficient derivative. Multi-point immobilization on agarose led to an extraordinary thermal stability (half-lives 3604 and 164-fold higher than the free enzyme, at 50° and 35 °C, respectively). Even for chitosan activated with glutaraldehyde, a low-cost support, thermal stability of the immobilized enzyme was 326 and 12-fold higher than the free enzyme at 50° and 35°C, respectively. Immobilized enzymes showed no release of any subunit for the agarose-glyoxyl derivative, and only a few ones for the support activated with glutaraldehyde. Most remarkably, the enzyme kinetic behavior after immobilization increased up to 4-fold in relation to the free one. ß-xylosidase, a tetrameric enzyme with four identical subunits, exists in equilibrium between the monomeric and oligomeric forms in solution. Depending on the pH of immobilization, the enzyme oligomerization can be favored, thus explaining the hyperactivation phenomenon. Both glyoxyl-agarose and chitosan-glutaraldehyde derivatives were used to catalyze corncob xylan hydrolysis, reaching 72 % conversion, representing a xylose productivity of around 20 g L-1 h-1. After ten 4h-cycles (pH 6.0, 35 °C), the xylan-to-xylose conversion remained approximately unchanged. Therefore, the immobilized ß-xylosidases prepared in this work can be of great interest as biocatalysts in a biorefinery context.
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Xilosidases , Estabilidade Enzimática , Enzimas Imobilizadas/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Xilanos , Xilosidases/genética , Xilosidases/metabolismoRESUMO
Various bio-based processes depend on controlled micro-aerobic conditions to achieve a satisfactory product yield. However, the limiting oxygen concentration varies according to the micro-organism employed, while for industrial applications, there is no cost-effective way of measuring it at low levels. This study proposes a machine learning procedure within a metabolic flux-based control strategy (SUPERSYS_MCU) to address this issue. The control strategy used simulations of a genome-scale metabolic model to generate a surrogate model in the form of an artificial neural network, to be used in a micro-aerobic fermentation strategy (MF-ANN). The meta-model provided setpoints to the controller, allowing adjustment of the inlet air flow to control the oxygen uptake rate. The strategy was evaluated in micro-aerobic batch cultures employing industrial Saccharomyces cerevisiae yeast, with defined medium and glucose as the carbon source, as a case study. The performance of the proposed control scheme was compared with a conventional fermentation and with three previously reported micro-aeration strategies, including respiratory quotient-based control and constant air flow rate. Due to maintenance of the oxidative balance at the anaerobiosis threshold, the MF-ANN provided volumetric ethanol productivity of 4.16 g·L-1 ·h-1 and a yield of 0.48 gethanol .gsubstrate-1 , which were higher than the values achieved for the other conditions studied (maximum of 3.4 g·L-1 ·h-1 and 0.35-0.40 gethanol ·gsubstrate-1 , respectively). Due to its modular character, the MF-ANN strategy could be adapted to other micro-aerated bioprocesses.
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Reatores Biológicos/microbiologia , Fermentação/fisiologia , Aprendizado de Máquina , Oxigênio/metabolismo , Anaerobiose , Técnicas de Cultura Celular por Lotes , Etanol/análise , Etanol/metabolismo , Análise do Fluxo Metabólico , Saccharomyces cerevisiae/metabolismoRESUMO
Attainment of a stable and highly active β-xylosidase is of major importance for the efficient and cost-competitive hydrolysis of hemicellulose xylan, as well as for its industrial conversion into biofuels and biochemicals. Here, a recombinant β-xylosidase of the glycoside hydrolase family (GH43) from Bacillus subtilis was produced in Escherichia coli culture, purified, and subsequently immobilized on agarose and chitosan. Glutaraldehyde and glyoxyl groups were evaluated as activating agents to select the most efficient derivative. Multi-point immobilization on agarose led to an extraordinary thermal stability (half-lives 3604 and 164-fold higher than the free enzyme, at 50° and 35 °C, respectively). Even for chitosan activated with glutaraldehyde, a low-cost support, thermal stability of the immobilized enzyme was 326 and 12-fold higher than the free enzyme at 50° and 35°C, respectively. Immobilized enzymes showed no release of any subunit for the agarose-glyoxyl derivative, and only a few ones for the support activated with glutaraldehyde. Most remarkably, the enzyme kinetic behavior after immobilization increased up to 4-fold in relation to the free one. β-xylosidase, a tetrameric enzyme with four identical subunits, exists in equilibrium between the monomeric and oligomeric forms in solution. Depending on the pH of immobilization, the enzyme oligomerization can be favored, thus explaining the hyperactivation phenomenon. Both glyoxyl-agarose and chitosan-glutaraldehyde derivatives were used to catalyze corncob xylan hydrolysis, reaching 72 % conversion, representing a xylose productivity of around 20 g L−1 h−1. After ten 4h-cycles (pH 6.0, 35 °C), the xylan-to-xylose conversion remained approximately unchanged. Therefore, the immobilized β-xylosidases prepared in this work can be of great interest as biocatalysts in a biorefinery context.
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The use of additives in the enzymatic saccharification of lignocellulosic biomass can have positive effects, decreasing the unproductive adsorption of cellulases on lignin and reducing the loss of enzyme activity. Soybean protein stands out as a potential lignin-blocking additive, but the economic impact of its use has not previously been investigated. Here, a systematic evaluation was performed of the process conditions, together with a techno-economic analysis, for the use of soybean protein in the saccharification of hydrothermally pretreated sugarcane bagasse in the context of an integrated 1G-2G ethanol biorefinery. Statistical experimental design methodology was firstly applied as a tool to select the process variable solids loading at 15% (w/w) and soybean protein concentration at 12% (w/w), followed by determination of enzyme dosage at 10 FPU/g and hydrolysis time of 24 h. The saccharification of sugarcane bagasse under these conditions enabled an increase of 26% in the amount of glucose released, compared to the control without additive. The retro-techno-economic analysis (RTEA) technique showed that to make the biorefinery economically feasible, some performance targets should be reached experimentally such as increasing biomass conversion to ideally 80% and reducing enzyme loading to 5.6 FPU/g in the presence of low-cost soybean protein.
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Saccharum/metabolismo , Proteínas de Soja/metabolismo , Biomassa , Celulose/metabolismo , Glycine max/metabolismoRESUMO
The impact of cultivation strategy on the cost of recombinant protein production is crucial for defining cost-effective bioreactor operation conditions. This paper presents a methodology to estimate and compare cost impacts related to utilities as well as medium composition, using simple design equations and accessible data. Data from batch bioreactor cultures were used as case study involving the production of pneumococcal surface protein A, a soluble recombinant protein, employing E. coli BL21(DE3). Cultivation strategies and corresponding process costs covered a wide range of operational conditions, including different media, inducers, and temperatures. The core expenses were related to the medium and cooling. When the price of peptone was above the threshold value of US$ 30/kg, defined medium became the best choice. IPTG and temperatures around 32⯰C led to shorter cultures and lower PspA4Pro production costs. The procedure offers a simple, accessible theoretical tool to identify cost-effective production strategies using bioreactors.
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The impact of cultivation strategy on the cost of recombinant protein production is crucial for defining cost-effective bioreactor operation conditions. This paper presents a methodology to estimate and compare cost impacts related to utilities as well as medium composition, using simple design equations and accessible data. Data from batch bioreactor cultures were used as case study involving the production of pneumococcal surface protein A, a soluble recombinant protein, employing E. coli BL21(DE3). Cultivation strategies and corresponding process costs covered a wide range of operational conditions, including different media, inducers, and temperatures. The core expenses were related to the medium and cooling. When the price of peptone was above the threshold value of US$ 30/kg, defined medium became the best choice. IPTG and temperatures around 32°C led to shorter cultures and lower PspA4Pro production costs. The procedure offers a simple, accessible theoretical tool to identify cost-effective production strategies using bioreactors.
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BACKGROUND: Fine-tuning the aeration for cultivations when oxygen-limited conditions are demanded (such as the production of vaccines, isobutanol, 2-3 butanediol, acetone, and bioethanol) is still a challenge in the area of bioreactor automation and advanced control. In this work, an innovative control strategy based on metabolic fluxes was implemented and evaluated in a case study: micro-aerated ethanol fermentation. RESULTS: The experiments were carried out in fed-batch mode, using commercial Saccharomyces cerevisiae, defined medium, and glucose as carbon source. Simulations of a genome-scale metabolic model for Saccharomyces cerevisiae were used to identify the range of oxygen and substrate fluxes that would maximize ethanol fluxes. Oxygen supply and feed flow rate were manipulated to control oxygen and substrate fluxes, as well as the respiratory quotient (RQ). The performance of the controlled cultivation was compared to two other fermentation strategies: a conventional "Brazilian fuel-ethanol plant" fermentation and a strictly anaerobic fermentation (with ultra-pure nitrogen used as the inlet gas). The cultivation carried out under the proposed control strategy showed the best average volumetric ethanol productivity (7.0 g L-1 h-1), with a final ethanol concentration of 87 g L-1 and yield of 0.46 gethanol g substrate -1 . The other fermentation strategies showed lower yields (close to 0.40 gethanol g substrate -1 ) and ethanol productivity around 4.0 g L-1 h-1. CONCLUSION: The control system based on fluxes was successfully implemented. The proposed approach could also be adapted to control several bioprocesses that require restrict aeration.
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Fermentação , Saccharomyces cerevisiae/crescimento & desenvolvimento , Saccharomyces cerevisiae/metabolismo , Reatores Biológicos , Etanol/metabolismo , Microbiologia Industrial , Oxigênio/metabolismoRESUMO
A potential strategy to mitigate problems related to unproductive adsorption of enzymes onto lignin during the saccharification of lignocellulosic biomass is the addition of lignin-blocking agents to the hydrolysis reaction medium. However, there is a clear need to find more cost-effective additives for use in large-scale processes. Here, selected alternative low-cost additives were evaluated in the saccharification of steam-exploded sugarcane bagasse using a commercial enzymatic cocktail. The addition of soybean protein, tryptone, peptone, and maize zein had positive effects on glucose release during the hydrolysis, with gains of up to 36% when 8% (w/w) soybean protein was used. These improvements were superior to those obtained using bovine serum albumin (BSA), a much more expensive protein that has been widely reported for such an application. Moreover, addition of soybean protein led to a saving of 48 h in the hydrolysis, corresponding to a 66% decrease in the reactor operation time required. In order to achieve the same hydrolysis yield without the soybean additive, the enzyme loading would need to be increased by 50%. FTIR spectroscopy and nitrogen elemental analysis revealed that the additives probably acted to reduce unproductive binding of cellulolytic enzymes onto the lignin portion of the sugarcane bagasse.
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Biomassa , Celulose/química , Lignina/química , Saccharum/química , Soroalbumina Bovina/química , Proteínas de Soja/química , Animais , Bovinos , Glucose/química , Hidrólise , VaporRESUMO
In the last years, Salmonella has been extensively studied not only due to its importance as a pathogen, but also as a host to produce pharmaceutical compounds. However, the full exploitation of Salmonella as a platform for bioproduct delivery has been hampered by the lack of information about its metabolism. Genome-scale metabolic models can be valuable tools to delineate metabolic engineering strategies as long as they closely represent the actual metabolism of the target organism. In the present study, a 13C-MFA approach was applied to map the fluxes at the central carbon pathways of S. typhimurium LT2 growing at glucose-limited chemostat cultures. The experiments were carried out in a 2L bioreactor, using defined medium enriched with 20% 13C-labeled glucose. Metabolic flux distributions in central carbon pathways of S. typhimurium LT2 were estimated using OpenFLUX2 based on the labeling pattern of biomass protein hydrolysates together with biomass composition. The results suggested that pentose phosphate is used to catabolize glucose, with minor fluxes through glycolysis. In silico simulations, using Optflux and pFBA as simulation method, allowed to study the performance of the genome-scale metabolic model. In general, the accuracy of in silico simulations was improved by the superimposition of estimated intracellular fluxes to the existing genome-scale metabolic model, showing a better fitting to the experimental extracellular fluxes, whereas the intracellular fluxes of pentose phosphate and anaplerotic reactions were poorly described.
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Mapeamento Cromossômico/métodos , Análise do Fluxo Metabólico/métodos , Redes e Vias Metabólicas/genética , Salmonella typhimurium/genética , Salmonella typhimurium/metabolismo , Biomassa , Reatores Biológicos , Isótopos de Carbono , Simulação por Computador , Cromatografia Gasosa-Espectrometria de Massas , Glucose/metabolismo , Glicólise , Engenharia Metabólica/métodosRESUMO
Over the past decades, most studies with xylanases have used Birchwood xylan as the standard substrate for activity assays. However, recently, Birchwood xylan production was discontinued by major suppliers, creating an important demand for a substitute. Ongoing and future studies require a substrate with characteristics equivalent to the discontinued xylan, in order to enable the comparison of results. In this context, a protocol for the production of a substrate similar to the discontinued commercial Birchwood xylan is reported. Obtained from bleached Eucalyptus cellulose pulp, xylan was extracted using 4% w/v NaOH solution at 25⯰C, precipitated with glacial acetic acid (HOAc), and freeze-dried. A thermal pretreatment in an autoclave for 15â¯min increased its solubility. The resulting xylan was characterized by infrared spectroscopy, thermogravimetry, and NMR. When assessing the activity of xylanases, the results were the same as those for commercial Birchwood xylan.
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A new approach is reported for techno-economic analysis of lignocellulosic ethanol production. With this methodology, general targets for key process variables can be draw, a valuable feedback for Research & Development teams. An integrated first- and second-generation ethanol from sugarcane biorefinery is presented as a case study for the methodology, with the biomass pretreated by liquid hot water, followed by enzymatic hydrolysis of the cellulose fraction. The hemicellulose fraction may be either fermented or biodigested. The methodology was able to identify the main variables that affect the process global economic performance: enzyme load in the cellulose hydrolysis reactor, cellulose-to-glucose, and xylose-to-ethanol yields. Windows of feasible operation are the graphical output of the methodology, outlining regions to be further explored experimentally. One example of quantitative result is that the maximum feasible enzyme load was 11.3â¯FPU/gcellulose when xylose is fermented to ethanol and 7.7â¯FPU/gcellulose when xylose is biodigested.
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Biocombustíveis , Etanol , Saccharum , Biomassa , Celulose , HidróliseRESUMO
Streptococcus pneumoniae is the main cause of pneumonia, meningitis, and other conditions that kill thousands of children every year worldwide. The replacement of pneumococcal serotypes among the vaccinated population has evidenced the need for new vaccines with broader coverage and driven the research for protein-based vaccines. Pneumococcal surface protein A (PspA) protects S. pneumoniae from the bactericidal effect of human apolactoferrin and prevents complement deposition. Several studies indicate that PspA is a very promising target for novel vaccine formulations. Here we describe a production and purification process for an untagged recombinant fragment of PspA from clade 4 (PspA4Pro), which has been shown to be cross-reactive with several PspA variants. PspA4Pro was obtained using lactose as inducer in Phytone auto-induction batch or glycerol limited fed-batch in 5-L bioreactor. The purification process includes two novel steps: (i) clarification using a cationic detergent to precipitate contaminant proteins, nucleic acids, and other negatively charged molecules as the lipopolysaccharide, which is the major endotoxin; and (ii) cryoprecipitation that eliminates aggregates and contaminants, which precipitate at -20 °C and pH 4.0, leaving PspA4Pro in the supernatant. The final process consisted of cell rupture in a continuous high-pressure homogenizer, clarification, anion exchange chromatography, cryoprecipitation, and cation exchange chromatography. This process avoided costly tag removal steps and recovered 35.3 ± 2.5% of PspA4Pro with 97.8 ± 0.36% purity and reduced endotoxin concentration by >99.9%. Circular dichroism and lactoferrin binding assay showed that PspA4Pro secondary structure and biological activity were preserved after purification and remained stable in a wide range of temperatures and pH values.
Assuntos
Proteínas de Bactérias/isolamento & purificação , Escherichia coli/genética , Extração Líquido-Líquido/métodos , Streptococcus pneumoniae/química , Proteínas de Bactérias/biossíntese , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Técnicas de Cultura Celular por Lotes , Reatores Biológicos , Clonagem Molecular , Detergentes/química , Endotoxinas/isolamento & purificação , Escherichia coli/química , Escherichia coli/metabolismo , Fermentação , Expressão Gênica , Glicerol/metabolismo , Concentração de Íons de Hidrogênio , Cinética , Lactoferrina/química , Lactose/metabolismo , Pressão , Ligação Proteica , Estrutura Secundária de Proteína , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Streptococcus pneumoniae/metabolismoRESUMO
BACKGROUND: Conservative surgical treatment has been the treatment of choice for early breast cancer. It allows feasible oncological treatment with a satisfactory cosmetic approach and fast recovery. However, in some cases mastectomy is necessary. This study proposes a surgical approach with only one surgical access through the same incision, which is in line with precepts mentioned above. It is called the prime incision and modified moving window techniques. METHODS: Thirty one patients with a breast cancer diagnosis who would have to undergo surgery were enrolled. The proposed technique was used and its advantages and feasibility were assessed and evaluated. RESULTS: Twenty three conservative surgeries, 7 adenectomies and 1 axillary surgery were performed. All cases were appropriately treated and progressed without complications and had adequate aesthetic results. The technique presented allows only one surgical access to approach the axilla and breast cancer treatment. CONCLUSION: This study proved the aesthetic advantage provided by only one surgical incision access feasible for surgical treatment as a secure approach. The minimally invasive approaches of prime incision and modified moving window were shown to provide adequate surgical access with only one scar, thus having a better cosmetic result.
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Live attenuated strains of Salmonella typhimurium have been extensively investigated as vaccines for a number of infectious diseases. However, there is still little information available concerning aspects of their metabolism. S. typhimurium and Escherichia coli show a high degree of similarity in terms of their genome contents and metabolic networks. However, this work presents experimental evidence showing that significant differences exist in their abilities to direct carbon fluxes to biomass and energy production. It is important to study the metabolism of Salmonella to elucidate the formation of acetate and other metabolites involved in optimizing the production of biomass, essential for the development of recombinant vaccines. The metabolism of Salmonella under aerobic conditions was assessed using continuous cultures performed at dilution rates ranging from 0.1 to 0.67 h(-1), with glucose as main substrate. Acetate assimilation and glucose metabolism under anaerobic conditions were also investigated using batch cultures. Chemostat cultivations showed deviation of carbon towards acetate formation, starting at dilution rates above 0.1 h(-1). This differed from previous findings for E. coli, where acetate accumulation was only detected at dilution rates exceeding 0.4 h(-1), and was due to the lower rate of acetate assimilation by S. typhimurium under aerobic conditions. Under anaerobic conditions, both microorganisms mainly produced ethanol, acetate, and formate. A genome-scale metabolic model, reconstructed for Salmonella based on an E. coli model, provided a poor description of the mixed fermentation pattern observed during Salmonella cultures, reinforcing the different patterns of carbon utilization exhibited by these closely related bacteria.
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Escherichia coli/metabolismo , Redes e Vias Metabólicas , Metaboloma , Salmonella typhimurium/metabolismo , Aerobiose , Anaerobiose , Biomassa , Reatores Biológicos/microbiologia , Meios de Cultura/química , Escherichia coli/genética , Fermentação , Glucose/metabolismo , Salmonella typhimurium/genética , Vacinas Sintéticas/biossínteseRESUMO
Genetically attenuated microorganisms, pathogens, and some commensal bacteria can be engineered to deliver recombinant heterologous antigens to stimulate the host immune system, while still offering good levels of safety. A key feature of these live vectors is their capacity to stimulate mucosal as well as humoral and/or cellular systemic immunity. This enables the use of different forms of vaccination to prevent pathogen colonization of mucosal tissues, the front door for many infectious agents. Furthermore, delivery of DNA vaccines and immune system stimulatory molecules, such as cytokines, can be achieved using these special carriers, whose adjuvant properties and, sometimes, invasive capacities enhance the immune response. More recently, the unique features and versatility of these vectors have also been exploited to develop anti-cancer vaccines, where tumor-associated antigens, cytokines, and DNA or RNA molecules are delivered. Different strategies and genetic tools are constantly being developed, increasing the antigenic potential of agents delivered by these systems, opening fresh perspectives for the deployment of vehicles for new purposes. Here we summarize the main characteristics of the different types of live bacterial vectors and discuss new applications of these delivery systems in the field of vaccinology.
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Animais , Humanos , Vacinas Bacterianas/imunologia , Portadores de Fármacos , Infecções Bacterianas/prevenção & controle , Vacinas Bacterianas/genética , Neoplasias/terapia , Organismos Geneticamente Modificados/genética , Organismos Geneticamente Modificados/imunologia , Vacinas Atenuadas/genética , Vacinas Atenuadas/imunologiaRESUMO
Genetically attenuated microorganisms, pathogens, and some commensal bacteria can be engineered to deliver recombinant heterologous antigens to stimulate the host immune system, while still offering good levels of safety. A key feature of these live vectors is their capacity to stimulate mucosal as well as humoral and/or cellular systemic immunity. This enables the use of different forms of vaccination to prevent pathogen colonization of mucosal tissues, the front door for many infectious agents. Furthermore, delivery of DNA vaccines and immune system stimulatory molecules, such as cytokines, can be achieved using these special carriers, whose adjuvant properties and, sometimes, invasive capacities enhance the immune response. More recently, the unique features and versatility of these vectors have also been exploited to develop anti-cancer vaccines, where tumor-associated antigens, cytokines, and DNA or RNA molecules are delivered. Different strategies and genetic tools are constantly being developed, increasing the antigenic potential of agents delivered by these systems, opening fresh perspectives for the deployment of vehicles for new purposes. Here we summarize the main characteristics of the different types of live bacterial vectors and discuss new applications of these delivery systems in the field of vaccinology.
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Humanos , Animais , Vacinas Bacterianas/imunologia , Portadores de Fármacos , Infecções Bacterianas/prevenção & controle , Vacinas Bacterianas/genética , Neoplasias/terapia , Organismos Geneticamente Modificados/genética , Organismos Geneticamente Modificados/imunologia , Vacinas Atenuadas/genética , Vacinas Atenuadas/imunologiaRESUMO
Lignocellulosic biomass is mainly composed of cellulose, hemicellulose, and lignin. Fuzzy logic, in turn, is a branch of many-valued logic based on the paradigm of inference under vagueness. This paper presents a methodology, based on computational intelligence, for modeling the kinetics of a complex reactional system. The design of a fuzzy interpolator to model cellulose hydrolysis is reported, within the perspective of applying kinetic models in bioreactor engineering. Experimental data for various types of lignocellulosic materials were used to develop the interpolator. New experimental data from the enzymatic hydrolysis of a synthetic substrate, on the other hand, were used to validate the methodology. The accuracy of the results indicates that this is a promising approach to extend the application of models fitted for specific situations to different cases, thus enhancing their generality.
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Lignina/metabolismo , Modelos Químicos , Animais , Reatores Biológicos , Celulase/metabolismo , Análise por Conglomerados , Hidrólise , Cinética , Trichoderma/enzimologiaRESUMO
Genetically attenuated microorganisms, pathogens, and some commensal bacteria can be engineered to deliver recombinant heterologous antigens to stimulate the host immune system, while still offering good levels of safety. A key feature of these live vectors is their capacity to stimulate mucosal as well as humoral and/or cellular systemic immunity. This enables the use of different forms of vaccination to prevent pathogen colonization of mucosal tissues, the front door for many infectious agents. Furthermore, delivery of DNA vaccines and immune system stimulatory molecules, such as cytokines, can be achieved using these special carriers, whose adjuvant properties and, sometimes, invasive capacities enhance the immune response. More recently, the unique features and versatility of these vectors have also been exploited to develop anti-cancer vaccines, where tumor-associated antigens, cytokines, and DNA or RNA molecules are delivered. Different strategies and genetic tools are constantly being developed, increasing the antigenic potential of agents delivered by these systems, opening fresh perspectives for the deployment of vehicles for new purposes. Here we summarize the main characteristics of the different types of live bacterial vectors and discuss new applications of these delivery systems in the field of vaccinology.