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Ibrahim M.M.,National Research Center of Egypt | El-Zawawy W.K.,National Research Center of Egypt | Abdel-Fattah Y.R.,Universities and Research Institutes Zone | Soliman N.A.,Universities and Research Institutes Zone | Agblevor F.A.,Virginia Polytechnic Institute and State University
Carbohydrate Polymers | Year: 2011

Agricultural residues, such as rice straw, are renewable, largely unused, and abundantly available resources. They contain cellulose and hemicellulose, which could be used to produce ethanol and many other value-added products. The current research investigates the utilization of rice straw as a lignocellulosic biomass feedstock to produce a value-added product. Investigation was carried to convert the rice straw into glucose which can be further fermented to produce ethanol. Different pretreatment methods, such as chemical pretreatment process using alkaline pulping and steam explosion were applied in this study to pretreat the lignocellulosic biomass. A Spezyme CP® cellulase enzyme was used in the experiment to hydrolyze the pretreated material into glucose. The total reducing sugars produced from the enzymatic hydrolysis of cellulose was measured by the dinitrosalicylic acid (DNS) method. The data from the enzyme hydrolysis time study were analyzed to provide information on enzyme hydrolysis rates. The results indicated that 28.9-58.4 g/L of glucose can be produced from rice straw depending on the pretreatment method. © 2010 Elsevier Ltd. All rights reserved. Source

El-Zawawy W.K.,National Research Center of Egypt | Ibrahim M.M.,National Research Center of Egypt | Abdel-Fattah Y.R.,Universities and Research Institutes Zone | Soliman N.A.,Universities and Research Institutes Zone | Mahmoud M.M.,Universities and Research Institutes Zone
Carbohydrate Polymers | Year: 2011

The current research investigates the use of acid and enzyme hydrolysis to produce glucose from pretreated rice straw, banana plant waste and corn cob, as a lignocellulosic materials, to be a source for ethanol production. The agricultural biomasses were first tested, then a laboratory experimental set-up was designed in order to perform the necessary conversions. The biomass materials were characterized to contain 57.46-85.28% holocellulose and 14.55-26.12% lignin. Conversion of the cellulose to glucose was achieved by pre-treatment method for the agricultural residues first applying chemical pulping and steam explosion method as well as microwave treatment then followed by two processes, namely acid hydrolysis and enzyme hydrolysis. Sulfuric acid, 5%, was used in acid hydrolysis and Trichoderma reesei cellulases in enzyme hydrolysis. These experiments demonstrated that glucose concentration differs according to the type of pre-treatment and type of hydrolysis. Conversion of the glucose to ethanol during fermentation was accomplished by the action of yeasts from Saccharomyces cerevisiae. Ethanol production in the culture sample was monitored using gas chromatography. The results indicate that ethanol can be made from the above mentioned residues in a different yield according to the pre-treatment and the glucose produced from the hydrolysis method. © 2010 Elsevier Ltd. All rights reserved. Source

Abdel-Fattah Y.R.,Universities and Research Institutes Zone | Soliman N.A.,Universities and Research Institutes Zone | El-Toukhy N.M.,Genetic Engineering and Biotechnology Research Institute GEBRI | El-Gendi H.,Universities and Research Institutes Zone | Ahmed R.S.,Universities and Research Institutes Zone
Journal of Chemistry | Year: 2013

An optimization strategy, based on statistical experimental design, is employed to enhance the production of thermostable α-amylase by a thermotolerant B. licheniformis AI20 isolate. Using one variant at time (OVAT) method, starch, yeast extract, and CaCl2 were observed to influence the enzyme production significantly. Thereafter, the response surface methodology (RSM) was adopted to acquire the best process conditions among the selected variables, where a three-level Box-Behnken design was employed to create a polynomial quadratic model correlating the relationship between the three variables and α-amylase activity. The optimal combination of the major constituents of media for α-amylase production was 1.0% starch, 0.75% yeast extract, and 0.02% CaCl2. The predicted optimum α-amylase activity was 384 U/mL/min, which is two folds more than the basal medium conditions. The produced α-amylase was purified through various chromatographic techniques. The estimated enzyme molecular mass was 55 kDa and the α-amylase had an optimal temperature and pH of 60-80°C and 6-7.5, respectively. Values of V max and K m for the purified enzyme were 454 mU/mg and 0.709 mg/mL. The α-amylase enzyme showed great stability against different solvents. Additionally, the enzyme activity was slightly inhibited by detergents, sodium dodecyl sulphate (SDS), or chelating agents such as EDTA and EGTA. On the other hand, great enzyme stability against different divalent metal ions was observed at 0.1 mM concentration, but 10 mM of Cu2+ or Zn2+ reduced the enzyme activity by 25 and 55%, respectively. © 2013 Yasser R. Abdel-Fattah et al. Source

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