Truffle mycelia exhibit a complex interaction pattern with host plants and have been extensively studied over the last years as a source of new bioactive compounds. Fungal enzymes possess a wide use in food industry, ...Truffle mycelia exhibit a complex interaction pattern with host plants and have been extensively studied over the last years as a source of new bioactive compounds. Fungal enzymes possess a wide use in food industry, confectionaries, textiles and leather industries in order to simplify the processing of raw materials. They are often more stable than enzymes derived from other sources. Tuber maculatum and Tuber aestivum mycelia were tested for enzymes production in Petri dishes solid medium conditions. The results showed that Tuber maculatum produced seven extracellular enzymes (amylase, xylanase, laccase, lipase, peroxidase, cellulase and catalase) while Tuber aestivum produced only three enzymes (amylase, peroxidase and catalase).展开更多
Heterofermentative lactic acid bacterium Lactobacillus brevis may be considered as a promising host for heterologous butanol synthesis because of tolerance to butanol and ability to ferment pentose and hexose sugars f...Heterofermentative lactic acid bacterium Lactobacillus brevis may be considered as a promising host for heterologous butanol synthesis because of tolerance to butanol and ability to ferment pentose and hexose sugars from wood hydrolysates that are cheap and renewable carbohydrate source. Carbon and electron flow was evaluated in two L. brevis strains in order to assess metabolic potential of these bacteria for heterologous butanol synthesis. Conditions required for generation of acetyl-CoA and NADH which are necessary for butanol biosynthesis have been determined. Key enzymes controlling direction of metabolic fluxes in L. brevis in various redox conditions were defined. In anaerobic glucose fermentation, the carbon flow through acetyl-CoA is regulated by aldehyde dehydrogenase ALDH possessing low affinity to NADH and activity (KmNADH= 200 μM, Vmax= 0.03 U/mg of total cell protein). Aerobically, the NADH-oxidase NOX (KmNADH= 25 μM, Vmax = 1.7 U/mg) efficiently competes with ALDH for NADH that results in formation of acetate instead of acetyl-CoA. In general, external electron acceptors (oxygen, fructose) and pentoses decrease NADH availability for native ethanol and recombinant butanol enzymes and therefore reduce carbon flux through acetyl-CoA. Pyruvate metabolism was studied in order to reveal redirection possibilities of competitive carbon fluxes towards butanol synthesis. The study provides a basis for the rational development of L. brevis strains producing butanol from wood hydrolysate.展开更多
The accurate prediction of the droplet size distribution(DSD)in liquid–liquid turbulent dispersions is of fundamental importance in many industrial applications and it requires suitable kernels in the population bala...The accurate prediction of the droplet size distribution(DSD)in liquid–liquid turbulent dispersions is of fundamental importance in many industrial applications and it requires suitable kernels in the population balance model.When a surfactant is included in liquid–liquid dispersions,the droplet breakup behavior will change as an effect of the reduction of the interfacial tension.Moreover,also the dynamic interfacial tension may be different with respect to the static,due to the fact that the surfactant may be easily desorbed from the droplet surface,generating additional disruptive stresses.In this work,the performance of five breakup kernels from the literature is assessed,to investigate their ability to predict the time evolution of the DSD and of the mean Sauter diameter,when different surfactants are employed.Simulations are performed with the Quadrature Method of Moments for the solution of the population balance model coupled with the two-fluid model implemented in the compressible Two Phase Euler Foam solver of the open-source computational fluid dynamics(CFD)code Open FOAM v.2.2.x.The time evolution of the mean Sauter diameter predicted by these kernels is validated against experimental data for six test cases referring to a stirred tank with different types of surfactants(Tween 20 and PVA 88%)at different concentrations operating under different stirrer rates.Our results show that for the dispersion containing Tween 20 additional stress is generated,the multifractal breakup kernel properly predicts the DSD evolution,whereas two other kernels predict too fast breakup of droplets covered by adsorbed PVA.Kernels derived originally for bubbles completely fail.展开更多
Tuber aestivum/uncinatum has been widely used as food, food additives, and traditional medicine. Truffles are extremely perishable with a short postharvest life quality requiring a special handling for marketing in or...Tuber aestivum/uncinatum has been widely used as food, food additives, and traditional medicine. Truffles are extremely perishable with a short postharvest life quality requiring a special handling for marketing in order to delay its deterioration. This study aimed to assess the effects of different sanitizing methods on superficial Tuber aestivium quality ascocarp. The results showed that the best treatment was obtained by immersing the Truffle ascocarps in boiling water for 1 or 2 min where counts of total mesophilic microoraganisms (TMM) were respectively 81 and 7 CFU per g of dry Truffle ascocarps biomass, respectively. However, the highest TMM was obtained after rinsing Truffle ascocarps in 2% NaOH where recovery was 108 CFU per g of dry Truffle ascocarps biomass. Treatments applied to disinfect Truffle ascocarps were classified by increasing degree of efficiency as follows to reduce the microbial load expressed in CFU/g: Dipping in boiling water (2 min) 7 ± 3.41;dipping in boiling water (1 min) 81 ± 25.8, rinsing with alcohol 2.102 ± 13;rinsing with tap water 6.103 ± 36;rinsing with H2O2 6.104 ± 2;brushing 2.105 ± 28 and rinsing with NaOH 108 ± 15.展开更多
The present work proposes a novel radially cross-flow multistage solid-liquid circulating fluidized bed （SLCFB）. The SLCFB primarily consists of a single multistage column （having an inner diameter of 100 mm and le...The present work proposes a novel radially cross-flow multistage solid-liquid circulating fluidized bed （SLCFB）. The SLCFB primarily consists of a single multistage column （having an inner diameter of 100 mm and length of 1.40 m）, which is divided into two sections wherein both the steps of utilization or loading （e.g., adsorption and catalytic reaction） and regeneration of the solid phase can be carried out simulta- neously in continuous mode. The hydrodynamic characteristics were studied using ion exchange resin as the solid phase and water as the fluidizing medium. The loading and flooding states were determined for three particle sizes; i.e,. 0.30, 0,42, and 0.61 ram. The effects of the superficial liquid velocity and solid feed rate on the solid hold-up were investigated under loading and flooding conditions. The solid hold-up increases with an increase in the solid feed rate and decreases with an increase in the superficial liquid velocity. An artificial-intelligence formalism, namely the multilayer perceptron neural network （MLPNN）, was employed for the prediction of the solid hold-up. The input space of MLPNN-based model consists of four parameters, representing operating and system parameters of the proposed SLCFB. The developed MLPNN-based model has excellent prediction accuracy and generalization capability.展开更多
文摘Truffle mycelia exhibit a complex interaction pattern with host plants and have been extensively studied over the last years as a source of new bioactive compounds. Fungal enzymes possess a wide use in food industry, confectionaries, textiles and leather industries in order to simplify the processing of raw materials. They are often more stable than enzymes derived from other sources. Tuber maculatum and Tuber aestivum mycelia were tested for enzymes production in Petri dishes solid medium conditions. The results showed that Tuber maculatum produced seven extracellular enzymes (amylase, xylanase, laccase, lipase, peroxidase, cellulase and catalase) while Tuber aestivum produced only three enzymes (amylase, peroxidase and catalase).
基金supported in part by the Ministry of Education and Science of the Russian Federation(EurAsES program,contract№16.M04.12.0017)by Academy of Finland(grant№137469,15.04.2010 ap-plied by Tom Granstrom).
文摘Heterofermentative lactic acid bacterium Lactobacillus brevis may be considered as a promising host for heterologous butanol synthesis because of tolerance to butanol and ability to ferment pentose and hexose sugars from wood hydrolysates that are cheap and renewable carbohydrate source. Carbon and electron flow was evaluated in two L. brevis strains in order to assess metabolic potential of these bacteria for heterologous butanol synthesis. Conditions required for generation of acetyl-CoA and NADH which are necessary for butanol biosynthesis have been determined. Key enzymes controlling direction of metabolic fluxes in L. brevis in various redox conditions were defined. In anaerobic glucose fermentation, the carbon flow through acetyl-CoA is regulated by aldehyde dehydrogenase ALDH possessing low affinity to NADH and activity (KmNADH= 200 μM, Vmax= 0.03 U/mg of total cell protein). Aerobically, the NADH-oxidase NOX (KmNADH= 25 μM, Vmax = 1.7 U/mg) efficiently competes with ALDH for NADH that results in formation of acetate instead of acetyl-CoA. In general, external electron acceptors (oxygen, fructose) and pentoses decrease NADH availability for native ethanol and recombinant butanol enzymes and therefore reduce carbon flux through acetyl-CoA. Pyruvate metabolism was studied in order to reveal redirection possibilities of competitive carbon fluxes towards butanol synthesis. The study provides a basis for the rational development of L. brevis strains producing butanol from wood hydrolysate.
文摘The accurate prediction of the droplet size distribution(DSD)in liquid–liquid turbulent dispersions is of fundamental importance in many industrial applications and it requires suitable kernels in the population balance model.When a surfactant is included in liquid–liquid dispersions,the droplet breakup behavior will change as an effect of the reduction of the interfacial tension.Moreover,also the dynamic interfacial tension may be different with respect to the static,due to the fact that the surfactant may be easily desorbed from the droplet surface,generating additional disruptive stresses.In this work,the performance of five breakup kernels from the literature is assessed,to investigate their ability to predict the time evolution of the DSD and of the mean Sauter diameter,when different surfactants are employed.Simulations are performed with the Quadrature Method of Moments for the solution of the population balance model coupled with the two-fluid model implemented in the compressible Two Phase Euler Foam solver of the open-source computational fluid dynamics(CFD)code Open FOAM v.2.2.x.The time evolution of the mean Sauter diameter predicted by these kernels is validated against experimental data for six test cases referring to a stirred tank with different types of surfactants(Tween 20 and PVA 88%)at different concentrations operating under different stirrer rates.Our results show that for the dispersion containing Tween 20 additional stress is generated,the multifractal breakup kernel properly predicts the DSD evolution,whereas two other kernels predict too fast breakup of droplets covered by adsorbed PVA.Kernels derived originally for bubbles completely fail.
文摘Tuber aestivum/uncinatum has been widely used as food, food additives, and traditional medicine. Truffles are extremely perishable with a short postharvest life quality requiring a special handling for marketing in order to delay its deterioration. This study aimed to assess the effects of different sanitizing methods on superficial Tuber aestivium quality ascocarp. The results showed that the best treatment was obtained by immersing the Truffle ascocarps in boiling water for 1 or 2 min where counts of total mesophilic microoraganisms (TMM) were respectively 81 and 7 CFU per g of dry Truffle ascocarps biomass, respectively. However, the highest TMM was obtained after rinsing Truffle ascocarps in 2% NaOH where recovery was 108 CFU per g of dry Truffle ascocarps biomass. Treatments applied to disinfect Truffle ascocarps were classified by increasing degree of efficiency as follows to reduce the microbial load expressed in CFU/g: Dipping in boiling water (2 min) 7 ± 3.41;dipping in boiling water (1 min) 81 ± 25.8, rinsing with alcohol 2.102 ± 13;rinsing with tap water 6.103 ± 36;rinsing with H2O2 6.104 ± 2;brushing 2.105 ± 28 and rinsing with NaOH 108 ± 15.
文摘The present work proposes a novel radially cross-flow multistage solid-liquid circulating fluidized bed （SLCFB）. The SLCFB primarily consists of a single multistage column （having an inner diameter of 100 mm and length of 1.40 m）, which is divided into two sections wherein both the steps of utilization or loading （e.g., adsorption and catalytic reaction） and regeneration of the solid phase can be carried out simulta- neously in continuous mode. The hydrodynamic characteristics were studied using ion exchange resin as the solid phase and water as the fluidizing medium. The loading and flooding states were determined for three particle sizes; i.e,. 0.30, 0,42, and 0.61 ram. The effects of the superficial liquid velocity and solid feed rate on the solid hold-up were investigated under loading and flooding conditions. The solid hold-up increases with an increase in the solid feed rate and decreases with an increase in the superficial liquid velocity. An artificial-intelligence formalism, namely the multilayer perceptron neural network （MLPNN）, was employed for the prediction of the solid hold-up. The input space of MLPNN-based model consists of four parameters, representing operating and system parameters of the proposed SLCFB. The developed MLPNN-based model has excellent prediction accuracy and generalization capability.
