Enzymatic Synthesis of Theanine in the Presence of L-glutaminase Produced by Trichoderma koningii

Background and Objective: Since ancient times, it has been said that drinking green tea brings relaxation. The substance that is responsible for a sense of relaxation is theanine. Theanine (γ-glutamylethylamide) is a unique non-protein amino acid. It gives an umami taste and a unique flavor to the tea, and has many physiological and pharmaceutical effects such as anti-tumor, anti-cancer, neuro-protective, anti-hypertensive and anti-obesity effects; it may further help in relaxation and increase focus. So this compound is essential for human body; however, it is not synthesized in the body and should be administrated orally. In the present study, the enzymatic biosynthesis of theanine was examined in the presence of Ethylamine and L-glutamine, and for the first time the enzyme was produced by the fungal strain Trichoderma koningii. Material and Methods: At first, solid state fermentation was carried out for the production of L-glutaminase by the fungal strain Trichoderma koningii using sesamum oil cake as the solid substrate. Then the biosynthesis of theanine was performed in the presence of extracted enzyme solution, and ethylamine and L-glutamine as substrates. The concentration of effective parameters, namely L-glutamine and ethylamine, and the volume of enzyme solution on theanine production were evaluated based on the response surface methodology coupled with central composite design. 16 experiments were designed by the design expert software and carried out to examine the changes of theanine concentration with changes in the concentration of ethylamine and L-glutamine and the volume of enzyme solution. Results and Conclusion: This investigation indicated simultaneous synthesis of theanine as well as hydrolysis of L-glutamine and L-glutamic acid. Selected independent variables (including ethylamine concentration, L-glutamine concentration and enzyme solution volume) were effective on theanine concentration. Increase of enzyme solution volume had a significant effect on theanine concentration. The highest theanine concentration (43 mM) was obtained at the ethylamine concentration of 0.9 M, L-glutamine concentration of 0.3 M and enzyme solution of 3 ml. Conflict of interest: The authors declare no conflict of interest

Suppressed Acrylamide Formation during Baking in Yeast-Leavened Bread Based on added Asparaginase, Baking Time and Temperature Using Response Surface Methodology

 Background and Objective: Acrylamide as a toxic substance for human beings is produced by Maillard reaction at high temperatures. In this research, this reaction can be inhibited based on using aspariganse enzyme, controlling the cooking time and temperature during baking in yeast-leavened bread.Material and Methods: In this study, a response surface methodology 5-level-3-factor central composite design was applied to study the effects of asparaginase (300-900 U Kg-1 of flour), baking temperature (230-280°C) and baking time (13-16 min) on acrylamide formation in yeast-leavened wheat bread.Results and Conclusion: Added asparaginase showed a reducing effect on acrylamide formation (p≤0.0001). Baking temperature significantly increased the acrylamide content in bread (p≤0.0001). A strong correlation was found between the baking temperature and acrylamide formation. Baking time and its interaction with asparaginase had a low but significant reducing effect on acrylamide content in bread (p≤0.0001). Three parameters of the cooking temperature and time as well as enzyme concentration have been optimized using response surface methodology, their values obtained 245.71°C, 14.55 min and 752.15 U Kg-1, respectively. Enzymatic process could be suggested as a safe and convenient method for preventing acrylamide formation in bread making.Conflict of interest: The authors declare no conflict of interest.

L-Sorbose Production by Gluconobacter oxydans using Submerged Fermentation in a Bench Scale Fermenter

 Background and objective: L-Sorbose, as a precursor of ascorbic acid, can be biologically produced using Gluconobacter oxydans. The aim of this study was to optimize production of L-Sorbose by controlling concentration of the substrates and starter cultures. Material and methods: In this study, effects of three various fermentation parameters on the concentration of L-sorbose were assessed using fermenter (28°C, 1.4 vvm) and response surface methodology. These parameters included quantities of D-sorbitol (120-180 g lDw-1) (Deionized water) and yeast extract (6-18 g lDw-1) and inoculum/substrate ratios (5-10%).Results and conclusion: Results showed that the fitted model with high values of R2 (0.9594) and R2-adjusted (0.9228) could effectively predict the concentration of L-sorbose within the highlighted ranges for the variables. Furthermore, results demonstrated that the maximum concentration of L-sorbose was achieved at 42.26 g lDW-1 using D-sorbitol, yeast extract and inoculum/substrate ratio values of 153.42 g lDW-1, 12.64 g lDW-1 and 9.88%, respectively. These results have revealed appropriately of response surface methodology for the prediction of L-sorbose product quantity and optimization of the variables in this aerobic fermentation process.Conflict of interest: The authors confirm that they have no conflict of interest

Effects of Sucrose, Skim Milk and Yeast Powder on Survival of Lactobacillus rhamnosus GG Encapsulated with Alginate during One-week Storage at room Conditions

Background and Objective: During the manufacture and storage of probiotic products, there are always possibilities that probiotics be exposed to harmful stresses such as high temperature, low pH, various osmotic pressures and high oxygen levels, which can decrease the number of living cells. Encapsulation is one of the methods used to protect living cells such as probiotic bacteria from environmental challenges. Up-to-date, various compounds with abilities to protect bacteria during freeze-drying and to increase viability during storage have been identified. In this study, alginate with calcium chloride was used to encapsulate probiotic bacteria using extrusion method. Then, effects of sucrose and skim milk as cryoprotectants and yeast powder containing beta-glucan as prebiotic on the survival of these bacteria were investigated. Material and Methods: The Homogeneous solution of bacteria with alginate and cry protectants were manually extruded into a calcium chloride solution. After 30 min of agitation, shaped beads were separated. For the comparison, bacterial population were enumerated in the primary culture, after encapsulation, freeze-drying and 1 week of storage at room conditions (N0, N, NF and N1w, respectively). To assess colony-forming unit per ml of the samples, first 1 g of fresh beads was dissolved in 9 ml of trisodium citrate and then serial dilution and pour plate techniques were carried out. Plates were incubated for 24-48 h and colonies were counted. Results and Conclusion: Results showed that encapsulation of bacteria with alginate and calcium chloride alone was 51% effective while use of yeast powder and sucrose with alginate increased the encapsulation efficiency to 97 and 99%, respectively. Furthermore, use of skim milk with alginate and sucrose resulted in the highest survival rate after 1 week of storage at room conditions. Therefore, encapsulation of probiotic bacteria with alginate layer and yeast powder containing prebiotics, sucrose and skim milk can be effective in survival of these bacteria. Conflict of interest: The authors declare no conflict of interest

Optimal Medium Composition to Enhance Poly-β-hydroxybutyrate Production by Ralstonia eutropha Using Cane Molasses as Sole Carbon Source

In order to reduce the costs associated with poly-β-hydroxybutyrate production, growth and poly-β-hydroxybutyrate production of Ralstonia eutropha were studied in batch culture on different carbon sources. Experiments were designed and conducted to not only lower the cost of poly-β-hydroxybutyrate production by using inexpensive substrates, but also to increase poly-β-hydroxybutyrate production by optimizing the culture medium composition. Low cost, abundant carbon sources, including cane molasses, beet molasses, soya bean, and corn steep liquor were used to investigate the possibility of poly-β-hydroxybutyrate production in such renewable carbon sources. Based on the experimental results, cane molasses with production of 0.49 gL-1 poly-β-hydroxybutyrate was selected as the most efficient carbon source. To improve bacterial growth and poly-β-hydroxybutyrate production, different chemicals were then used to pretreat the cane molasses. Sulfuric acid, with 33% enhancement in poly-β-hydroxybutyrate production, revealed the highest efficiency in removing heavy metals and suspended impurities and was used to pretreat cane molasses in the subsequent experiments. Additionally, to make the process even more efficient and ultimately more effective, urea and corn steep liquor were used as nitrogen/minerals and vitamin sources, respectively. Using the response surface methodology and through a 2n factorial central composite design, the medium composition was then optimized, and maximum biomass concentration of 5.03 gL-1 and poly-β-hydroxybutyrate concentration of 1.63 gL-1 were obtained

Study of the First Isolated Fungus Capable of Heavy Crude Oil Biodesulfurization [abstract]

Track II: Transportation and BiofuelsOnly abstract of poster available.To meet stringent emission standards stipulated by regulatory agencies, the oil industry is required to bring down the sulfur content of fuels. Oil supplies 38% of the worldwide energy, and as the light oil is limited and meanwhile the energy demand is increasing, it is a must to use heavy crude oil and therefore desulfurize it to meet environmental standards. As it is not feasible to desulfurize all the sulfur containing compounds of heavy crude oil by the existing methods (such as hydro-desulfurization) we have focused on biodesulfurization of heavy crude oil. We have isolated the first native fungus which has been identified as Stachybotrys sp. and is able to remove sulfur and nitrogen from heavy crude oil selectively at 30 °C. This fungus is able to desulfurize 76% and 64.8% of the sulfur content of heavy crude oil of Soroush oil field and Kuhemond oil field (with the initial sulfur contents of 5 wt % and 7.6 wt %, respectively) in 72 and 144 h, respectively. We have studied the impacts of several parameters on heavy crude oil biodesulfurization efficiency of our fungus strain such as initial pH of the medium, water−oil ratio, and number of spores in the suspension used for inoculation. This fungus strain has been isolated as a part of the heavy crude oil biodesulfurization project initiated by Petroleum Engineering Development Company (PEDEC), a subsidiary of National Iranian Oil Company

Curcumin Sustained Release with a Hybrid Chitosan-Silk Fibroin Nanofiber Containing Silver Nanoparticles as a Novel Highly Efficient Antibacterial Wound Dressing

Drug loading in electrospun nanofibers has gained a lot of attention as a novel method for direct drug release in an injury site to accelerate wound healing. The present study deals with the fabrication of silk fibroin (SF)-chitosan (CS)-silver (Ag)-curcumin (CUR) nanofibers using the electrospinning method, which facilitates the pH-responsive release of CUR, accelerates wound healing, and improves mechanical properties. Response surface methodology (RSM) was used to investigate the effect of the solution parameters on the nanofiber diameter and morphology. The nanofibers were characterized via Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), zeta potential, and Dynamic Light Scattering (DLS). CS concentration plays a crucial role in the physical and mechanical properties of the nanofibers. Drug loading and entrapment efficiencies improved from 13 to 44% and 43 to 82%, respectively, after the incorporation of Ag nanoparticles. The application of CS hydrogel enabled a pH-responsive release of CUR under acid conditions. The Minimum Inhibitory Concentration (MIC) assay on E. coli and S. aureus bacteria showed that nanofibers with lower CS concentration cause stronger inhibitory effects on bacterial growth. The nanofibers do not have any toxic effect on cell culture, as revealed by in vitro wound healing test on NIH 3T3 fibroblasts

Removal of Phenols with Encapsulated Horseradish Peroxidase in Calcium Alginate

Horseradish peroxidase was encapsulated in calcium alginate for the purpose of phenol removal. Considering enzyme encapsulation efficiency, retention activity and enzyme leakage of the capsules, the best gelation condition was found to be 1 % w/v of sodium alginate solution and 5.5 % w/v of calcium chloride hexahydrate. Upon immobilization, pH profile of enzyme activity changes as it shows higher value at basic and acidic solution. Besides, for each phenol concentration there would be an enzyme concentration which going further than this value has no significant effect on phenol removal. Investigation into time course of phenol removal for both encapsulated and free enzyme showed that encapsulated enzyme had nearly similar efficiency in comparison with the same concentration of free enzyme; however the capsules were reusable up to four cycles without any changes in their efficiency. The ratio of hydrogen peroxide/phenol at which highest phenol removal obtained, found to be dependent on initial phenol concentration and in the solution of 2 and 8 mM phenol it were 1.15 and 0.94 respectively

Phenol Removal from Industrial Wastewater by HRP Enzyme

In this research, horseradish peroxidase for phenol removal was utilized. First, the process was studied at the laboratory scale using a synthetic phenol solution (1-10) mM. Results showed that horseradish peroxidase (HRP) could effectively remove phenolic compounds from wastewater and that the catalytic capability of the enzyme was maintained for a wide range of pH, temperature, and aromatic concentration levels. The performance conditions were optimized for at lease 95% and 100% removal of phenolic compounds for both actual and synthetic wastewaters under high and low phenol concentrations (1 and 10 mM). The phenolic wastewater used was an olive mill effluent with a phenol concentration of 1221 mg/L (13 mM) and a pH value of 3.5. At the end of the reaction, the phenolic compounds changed to insoluble polymers and precipitated. Each enzyme/wastewater system was optimized for the following chemical dosages: hydrogen peroxide, enzyme, polyethylene glycol (PEG), and buffer. Furthermore, the reaction time to achieve at least 95% phenol removal was determined. According to the results, COD and BOD reduced to 58% and 78%, respectively. Experimental results showed an increase in H2O2 concentration beyond the optimum dose resulting from enzyme inactivation, thus reducing the phenol removal efficiency. On the other hand, increasing the enzyme, PEG, and/or reaction time beyond the optimum values resulted in only a marginal increase in removal efficiency

Encapsulation of Food Components and Bioactive Ingredients and Targeted Release

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