Home About us Contact
|
Home About us Contact | ||
|
|
||
U G (u + g)
Selected AbstractsCharacterization of a new tyrosinase from Pycnoporus species with high potential for food technological applicationsJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2005S. Halaouli Abstract Aims:, Tyrosinase production by Pycnoporus cinnabarinus and Pycnoporus sanguineus was screened among 20 strains originating from various geographical areas, particularly from tropical environments. The tyrosinase from the most efficient strain was purified and characterized and tested for food additive applications. Methods and Results:, Monophenolase and diphenolase activities of tyrosinase were measured from cell lysate from the 20 Pycnoporus strains, for 8,10 days of cultivation. The strain P. sanguineus CBS 614.73 showed the highest productivity (45·4 and 163·6 U g,1 protein per day for monophenolase and diphenolase respectively). P. sanguineus CBS 614.73 tyrosinase was purified from concentrated cell lysate, anion-exchange, size-exclusion and hydroxyapatite chromatography, with a final yield of 2% and a purification factor of 35,38. The pure enzyme was a monomere with a molecular mass of 45 kDa and it showed four isoforms or isoenzymes with pI between 4·5,5. No N-glycosylation was found. The N-terminal amino acid sequence was IVTGPVGGQTEGAPAPNR. The enzyme was shown to be almost fully active in a pH range of 6,7, in a large temperature range (30,70°C), and was stable below 60°C. The main kinetic constants were determined. The tyrosinase was able to convert p -tyrosol and p -coumaric acid into hydroxytyrosol and caffeic acid, respectively, and it could also catalyse the cross-linking formation of a model protein. Conclusions:, Among the genus Pycnoporus, known for the production of laccase, the strain P. sanguineus CBS 614.73 was shown to produce one other phenoloxidase, a new monomeric tyrosinase with a specific activity of 30 and 84 U mg,1 protein for monophenolase and diphenolase respectively. Significance and Impact of the Study:, This study identified P. sanguineus CBS 614.73 as a potential producer of a tyrosinase which demonstrated effectiveness in the synthesis of antioxidant molecules and in protein cross-linking. [source] A cost-effective cane molasses medium for enhanced cell-bound phytase production by Pichia anomalaJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2004A. Vohra Abstract Aim:, Formulation of an inexpensive cane molasses medium for improved cell-bound phytase production by Pichia anomala. Methods and Results:, Cell-bound phytase production by Pichia anomala was compared in synthetic glucose,beef extract and cane molasses media. The yeast was cultivated in 250 ml flasks containing 50 ml of the medium, inoculated with a 12 h-old inoculum (3 × 106 CFU ml,1) and incubated at 25°C for 24 h at 250 rev min,1. Different cultural parameters were optimized in cane molasses medium in batch fermentation. The cell-bound phytase content increased significantly in cane molasses medium (176 U g,1 dry biomass) when compared with the synthetic medium (100 U g,1 dry biomass). In fed-batch fermentation, a marked increase in biomass (20 g l,1) and the phytase yield (3000 U l,1) were recorded in cane molasses medium. The cost of production in cane molasses medium was £0·006 per 1000 U, which is much lower when compared with that in synthetic medium (£0·25 per 1000 U). Conclusions:, An overall 86·6% enhancement in phytase yield was attained in optimized cane molasses medium using fed-batch fermentation when compared with that in synthetic medium. Furthermore, the production in cane molasses medium is cost-effective. Significance and Impact of the Study:, Phytase yield was improved in cane molasses when compared with the synthetic medium, and the cost of production was also significantly reduced. This enzyme can find application in the animal feed industry for improving the nutritional status of feed and combating environmental pollution. [source] Production of ,-amylase under solid-state fermentation utilizing coffee wasteJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2009Pushpa S. Murthy Abstract Coffee industry substrates such as coffee pulp, coffee cherry husk, silver skin, spent coffee and mixtures of these coffee wastes (MC) were evaluated for their efficacy as sole carbon source for the synthesis of ,-amylase in solid-state fermentation (SSF) using a fungal strain of Neurospora crassa CFR 308. For SSF with coffee pulp and with MC, ,-amylase activity of 3908 U g,1 ds (units per gram of dry substrate) and 3870 U g,1 ds, respectively, was observed. Parameters such as moisture (60%), pH (4.6), temperature (28 °C), particle size (1.0 mm), inoculum size (107 spores g,1 ds), and fermentation time (5 days) were optimized for enzyme synthesis, wherein 4981 and 4324 U g,1 U g,1 ds of ,-amylase activity was obtained in SSF with coffee pulp and MC, respectively. The enzyme production was further improved when the substrates were subjected to pre-treatment by steaming. Accordingly, maximum ,-amylase activity of 7084 U g,1 ds and 6342 U g,1 ds was obtained with steam-pretreated coffee pulp and MC, respectively, demonstrating them to be excellent sole carbon sources for synthesis of ,-amylase production. Copyright © 2009 Society of Chemical Industry [source] Development of a mathematical model for Bacillus circulans growth and alkaline protease production kineticsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2009Chaganti Subba Rao Abstract BACKGROUND: An unstructured mathematical model was developed to understand information on the relationship between Bacillus circulans growth and metabolism-related protease production (using logistic and Luedeking,Piret equations respectively) in a batch reactor with respect to glucose consumption and fermentation time. The objective was to develop an indispensable tool for the optimisation, control, design and analysis of alkaline protease production. RESULTS: Biomass growth and enzyme production titres changed with a change in substrate concentration. Modelling analysis of biomass and enzyme production titres at different substrate concentrations revealed significant accuracy in terms of statistical consistency and robustness with respect to fermentation kinetic profiles. CONCLUSION: With the B. circulans strain used, an economic protease yield (2837 × 103 U g,1) with respect to biomass and glucose ratio was achieved at low substrate concentration (10 g L,1). The developed model could be effectively utilised for designing, controlling and up-scaling the protease production process in high-density fermentation in selected bioreactors with statistical consistency. Copyright © 2008 Society of Chemical Industry [source] Lactic acid fermentation of food waste using integrated glucoamylase productionJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2009Xiao Qiang Wang Abstract Commercial enzyme is usually needed for the bioconversion of organic waste or biomass. The overall cost could be reduced very significantly if enzyme production could be integrated with its application, avoiding unnecessary steps in enzyme production (such as concentration, recovery and transportation). This investigation attempted to integrate crude glucoamylase production with lactic acid fermentation of food waste. A maximum glucoamylase activity of 1850 U g,1 was obtained with Aspergillus nigerduring solid-state fermentation (SSF) of food waste, 14.8 times more than that obtained during submerged fermentation (SmF). The optimum pH for producing glucoamylase was 4.6, and glucoamylase retained 83.5% of peak activity at pH 3.0. Without any recovery treatment, the glucoamylase produced by SSF could be used directly for lactic acid fermentation of food waste. Lactic acid concentration reached 45.5 g L,1 with the addition of the crude enzyme, 72% higher than the control. No side-effects were caused by the viable A. niger in the crude enzyme. This work successfully integrated glucoamylase production with lactic acid fermentation. The enzyme produced by SSF of food waste had sufficient activity to be used directly without any treatment. The integrated process proposed in this study was very economical and may be helpful to other bioconversions. Copyright © 2008 Society of Chemical Industry [source] Inoculum strategies for Penicillium simplicissimum lipase production by solid-state fermentation using a residue from the babassu oil industryJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 3 2007Melissa L. E. Gutarra Abstract Two alternative inoculation strategies for lipase production by the fungus Penicillium simplicissimum were tested in solid-state fermentation using a residue from the babassu oil industry (babassu cake). Conventional spore inoculation was compared with fungal pellets grown in liquid medium and with inocula consisting of fermented cake. Fungal pellets delayed lipase production whereas fermented cake accelerated enzyme synthesis, yielding a productivity of 0.45 U g,1 h,1, which is equivalent to the highest values obtained with conventional inocula. Therefore, a 22 factorial design was used to determine the best conditions for lipase production with fermented cake as inoculum strategy, varying the inoculum propagation time and inoculum concentration. Lipase activity and productivity reached 30 U g,1 and 0.63 U g,1 h,1, respectively, with 10% inoculum and 36 h. Thus, fermented cake inocula increased production 1.5-fold with 10 times fewer spores than in conventional inoculation, indicating that fermented solids are an interesting alternative for inoculum development in solid-state fermentation, mainly for large-scale processes. Copyright © 2007 Society of Chemical Industry [source] A thermal study on the use of immobilized penicillin G acylase in the formation of 7-amino-3-deacetoxy cephalosporanic acid from cephalosporin GJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2004Jian-Liang Pan Abstract Penicillin G acylase (PGA) is an important enzyme for the industrial production of 7-amino-3-deacetoxy cephalosporanic acid (7-ADCA) from cephalosporin G (Ceph-G), and 6-aminopenicillanic acid (6-APA) from penicillin G (Pen-G). These products are used for the manufacture of semi-synthetic cephalosporins and penicillins. In this study, immobilized PGA was utilized to catalyze the conversion of Ceph-G to 7-ADCA. The optimal conditions were found to be an operating temperature of 45 °C, 0.2 M phosphate buffer, a substrate concentration of 30 mg cm,3 and a catalyst particle concentration of 0.01 g cm,3 (specific activity of 623.2 U g,1). Up to 45 °C the reaction was characterized by an activation energy of 38.66 kJ mol,1. Beyond 57.5 °C there was a sharp decline of activity, characterized by a deactivation energy of 235.88 kJ mol,1. Copyright © 2004 Society of Chemical Industry [source] Optimization of extraction of bulk enzymes from spent mushroom compostJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2003Avneesh D Singh Abstract The profiling of ligninase, hemicellulase and cellulase of Pleurotus sajor-caju after inoculation of spawn in bags containing sawdust was done at monthly intervals for a period of 6 months. Xylanase (EC 3.2.1.8) was produced throughout the 6 months studied with the productivity range from 5.60 to 7.51 U g,1. Cellulase (EC 3.2.1.4) and ,-glucosidase (EC 3.2.1.21) productivities were highest at 4 months, producing 3.31 U g,1 and 121.13 U g,1 respectively. Laccase (EC 1.10.3.2) productivity was highest at 2 months with a value of 7.59 U g,1. Lignin peroxidase (EC 1.11.1.14) productivity was highest at 5 months with a value of 206.20 U g,1. Total soluble proteins were highest at 4 months with a value of 0.139 mg cm,3. The profiling of lignin peroxidase in 5-month-old spent mushroom compost was monitored over a period of 10 months. It was observed that lignin peroxidase was produced throughout the period but productivity was variable. The average lignin peroxidase productivity ranged from 30 to 110 U g,1. The activities of the enzymes extracted in tap water at pH 8.4 were comparable to that extracted in 50 mmol sodium citrate buffer at pH 4.8 and distilled water at pH 5.2 at 4 °C using an incubator shaker at 200 rpm for 18 h. The optimum extraction time was 1 h using an incubator shaker at 4 °C. When an incubator shaker was used, there was no significant difference in the recovery of xylanase, cellulase and laccase at different pH values at 4 °C and 28 °C. No significant difference was observed in the recovery of ,-glucosidase using an incubator shaker at different pH values at 4 °C although the enzyme recovery was slightly higher at pH 8.12, with a value of 29.27 U g,1. The optimum extraction of ,-glucosidase was at pH 4 at room temperature using an incubator shaker. For the lignin peroxidase enzyme, the optimum pH for extraction was 6 at 4 °C and pH 7 at room temperature using an incubator shaker at 200 rpm for 1 h. Homogenization for 8 min at 8000 rpm using tap water at pH 4 had an advantage over the use of the incubator shaker for the extraction as high titers of enzymes were recovered. Copyright © 2003 Society of Chemical Industry [source] Optimization of enzymatic extraction of ferulic acid from wheat bran, using response surface methodology, and characterization of the resulting fractionsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2009Hélène Barberousse Abstract BACKGROUND: The agro-industries generate thousands of tons of by-products, such as bran or pulps, each year. They are, at best, used for cattle feeding. Through biocracking, this biomass may constitute a renewable source for various molecules of interest for the industry. For instance, ferulic acid, a compound showing antioxidant ability, is found in abundance in cereal bran. Its release depends mainly on the breaking of its ester linkage to other constitutive elements of the cell wall, such as arabinoxylans. Response surface methodology was used to evaluate the effects of ferulic acid esterase (FAE) and xylanase activities, as well as incubation time and temperature, on ferulic acid extraction yield from wheat bran. Under optimized conditions, the composition of the hydrolysate and of residual bran were compared to native bran. RESULTS: Experiments carried out under the predicted optimal conditions (FAE amount, 27 U g,1; xylanase amount, 304 U g,1; incubation time, 2 h; and temperature, 65 °C) led to an extraction yield of 52.8%, agreeing with the expected value (51.0%). The crude ferulic acid fraction was purified with Amberlite XAD16, leading to a final concentration of 125 µg mL,1 of ferulic acid in ethanol. The antioxidant capacity of this purified fraction was evaluated by the DPPH· scavenging method: it exhibited better efficiency (EC50 = 10.6 µmol L,1 in ferulic acid) than the ferulic acid standard (EC50 = 13.7 µmol L,1). CONCLUSION: These results confirm the potential of wheat bran valorization in the field of natural antioxidant extraction, possibly viable in an industrial scheme. Copyright © 2009 Society of Chemical Industry [source] Polyphenol oxidase activity in grass and its effect on plant-mediated lipolysis and proteolysis of Dactylis glomerata (cocksfoot) in a simulated rumen environmentJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2006Michael RF Lee Abstract Little is known about the level or activity of polyphenol oxidase (PPO) in grasses and its potential impact on proteolysis and lipolysis. Six grass species were initially screened for PPO activity (740.6, 291.9, 213.6, 119.0, 16.3 and 6.5 U g,1 fresh weight (FW) for cocksfoot, hybrid ryegrass, Italian ryegrass, perennial ryegrass, timothy and tall fescue respectively). Cocksfoot, which expressed the highest activity, was then used to determine the effect of PPO on plant-mediated proteolysis and lipolysis in a simulated rumen environment. Sourced cocksfoot was macerated and incubated in an antibiotic-containing anaerobic medium with or without ascorbate to deactivate PPO in the dark at 39 °C over five time points. At each time point (0, 1, 2, 6 and 24 h), six replicate samples were destructively harvested; three of the replicates were used for lipid analysis and the other three for protein, free amino acid and bound phenol determination. Characterisation of the herbage showed PPO activities of 649.6 and 0 U g,1 FW, which were reflected in the extent of phenol (derived from quinones) binding to protein after 24 h of incubation, namely 65.1 and 29.6 mg bound phenol g,1 protein (P < 0.001) for cocksfoot and cocksfoot + ascorbate respectively. Proteolysis, measured as free amino acids released into the incubation buffer, was significantly reduced (P < 0.001) with increasing PPO activity, with values after the 24 h incubation of 0.03 and 0.07 mmol L,1 g,1 FW for cocksfoot and cocksfoot + ascorbate respectively. Lipolysis, measured as the proportional decline in the membrane lipid polar fraction, was likewise reduced (P < 0.001) with increasing PPO activity, with values after the 24 h incubation of 0.43 and 0.65 for cocksfoot and cocksfoot + ascorbate respectively. Changes that occurred in protein and the lipid fractions (polar fraction, monoacylglycerol + diacylglycerol, triacylglycerol and free fatty acids) during the incubations are also reported and discussed. These results support the selection of forages high in PPO activity to reduce protein and lipid losses in silo and potentially in the rumen. Copyright © 2006 Society of Chemical Industry [source] Improved polygalacturonase production from Bacillus sp.LETTERS IN APPLIED MICROBIOLOGY, Issue 5 2002MG-cp-2 under submerged (SmF), solid state (SSF) fermentation Aims:,To investigate the effect of amino acids, vitamins and surfactants on polygalacturonase production from Bacillus sp. MG-cp-2 under submerged (SmF) and solid state fermentation (SSF). Methods and Results:,Bacillus sp. MG-cp-2 was isolated from the outer covering of the seeds of Celastrus paniculatus. Out of the various surfactants, amino acids and vitamins, Tween-60, DL -serine and folic acid maximally enhanced polygalacturonase production by 2·7-fold (240·0 U ml,1), 4·0-fold (360·0 U ml,1) and 3·8-fold (342·0 U ml,1) respectively, under submerged fermentation (SmF). In solid state fermentation (SSF), Tween-80, pyridoxine and DL -ornithine monohydrochloride induced highest enzyme production up to 1·73-fold (6956·5 U g,1), 5·3-fold (21224·4 U g,1) and 5·74-fold (23076·9 U g,1), respectively. Conclusion:,Amino acids and their analogues, vitamins and surfactants effect significantly polygalacturonase production by Bacillus sp. MG-cp-2 when grown under submerged (SmF) and solid state fermentation (SSF) conditions. Significance and Impact of the Study:,The study provides useful information about regulation of polygalacturonase biosynthesis in Bacillus sp. MG-cp-2, which appears to be an interplay of nutritional and physical factors. Alkaline polygalacturonase from Bacillus sp. MG-cp-2 will be extremely useful in the treatment of alkaline pectic waste waters from vegetable and fruit processing industries and in degumming of bast fibres. [source] Effect of dantrolene in an in vivo and in vitro model of myocardial reperfusion injuryACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2000B. Preckel Background: In skeletal muscle, dantrolene reduces free cytosolic calcium by inhibiting calcium release from the sarcoplasmic reticulum. A similar effect in ischemic-reperfused heart cells would protect myocardial tissue against reperfusion injury. We tested the hypothesis that dantrolene infusion during reperfusion protects the heart against reperfusion injury. Methods: Isovolumetric beating rat hearts were subjected to 30 min of ischemia followed by 60 min of reperfusion. Left ventricular (LV) developed pressure (LVDP) and creatine kinase release (CKR) were determined as indices of myocardial performance and cellular injury, respectively. In the treatment groups, dantrolene (25 (DAN25) or 100 (DAN100) ,mol l,1) was infused during the first 15 min of reperfusion; control hearts received the respective concentration of the vehicle (mannitol (CON25, CON100), each group n=7). To investigate the effects of dantrolene on reperfusion injury in vivo, 18 chloralose-anesthetized rabbits were subjected to 30 min occlusion and 180 min reperfusion of a major coronary artery. LV pressure (LVP), cardiac output (CO), and infarct size were determined. During the last 5 min of ischemia, nine rabbits received 10 mg kg,1 dantrolene intravenously (DAN). Another nine rabbits received the vehicle (dimethylsulfoxide) and served as controls (CON). Results: In isolated rat hearts, there was no recovery of LVDP in any group. Total CKR during 1 h of reperfusion was 845±76 (CON100) and 550±81 U g,1 dry mass (DAN100, P<0.05). In rabbits in vivo, hemodynamic baseline values were similar between groups (CON vs. DAN: LVP, 99±6 (mean±SEM) vs. 91±6mm Hg, P=0.29; CO, 252±26 vs. 275±23 ml min,1, P=0.53). During coronary artery occlusion, LVP and CO were reduced in both groups (CON: LVP, 89±3%; CO, 90±5% of baseline values) and LVP did not recover to baseline values during reperfusion (51±5% (CON) vs. 67±7% (DAN) of baseline, P=0.10). Infarct size was 41±4% of the area at risk in controls and 37±6% in dantrolene treated hearts (P=0.59). Conclusions: Dantrolene reduced CKR, indicating an attenuation of lethal cellular reperfusion injury in isolated rat hearts. However, in the rabbit in vivo, there was no effect on the extent of reperfusion injury after regional myocardial ischemia. [source] | |||||||||||||