الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
This work deals with isolation and screening of cellulase producing microorganisms. Moreover, the optimization of cellulase production conditions was studied to reach the maximum enzyme production. The produced cellulase enzyme as well as some other lignocellulose degrading enzymes were applied in some lignocellulosic materials (corn stover) degradation. from fifty isolates, two isolates showed maximum zones of clearance around their colonies and were thus found to have the highest cellulase activity. These two isolates which designated as A7 and B25 were selected and identified as Streptomyces griseus and Paenibacillus polymyxa, respectively. In addition, ten different microbial strains were tested for their cellulase and protein production capability, T. viride and C. globosum were selected for further cellulase production studies. Reese and Mandels basal medium was the best medium for growth, protein synthesis and cellulase production for all of the investigated strains. glucose was found to induce cellulase formation and protein synthesis of C. globosum and T. viride when used at concentrations of 0.10 and 0.15%, respectively. 2.0% cellulose was the optimum concentration for enzyme activity and protein synthesis of T. viride and S. griseus. While, the maximum cellulase activity of P. polymyxa (0.26 U/ml) was found at 1.0% cellulose. Among the tested organic and inorganic nitrogen sources, urea was found to be optimal for growth, protein synthesis, and cellulase production by C. globosum and T. viride. Yeast extract was shown to be the most suitable nitrogen source for Paenibacillus polymyxa and Streptomyces griseus. Initial pH 6 was the optimum for C. globosum and S. griseus, while pH 5 was found to be optimal for growth, protein synthesis and cellulase production by T. viride. Extracellular cellulase activity of P. polymyxa reached a maximum of 0.51 U/ml at pH 7. The maximum cellulase activities of C. globosum and T. viride was obtained after 8 days of fermentation. The highest cellulase activities and protein concentrations of P. polymyxa were obtained after 4 and 10 days, respectively. Six days of fermentation were best suitable for the formation of cellulase by S. griseus. Cellulase activities of C. globosum and S. griseus reached maximum activities of 1.45 and 1.06 U/ml, respectively, at 8% (v/v) inoculum volume. An inoculum volume of 5% was more favorable for formation of cellulase by T. viride and P. polymyxa (1.16 and 0.55 U/ml) respectively. The cellulase activity increased with increasing concentrations of Tween 80 up to 1.5 ml/L for T. viride and P. polymyxa with maximum activities of 1.29 and 0.64 U/ml, respectively. In addition, a concentration of 1.0 ml/L was found to be the most suitable for cellulase formation by C. globosum and S. griseus. The culture supernatant of C. globosum was concentrated by ultrafiltration. Cellulase and protein yields after concentration were 60.2 and 35.6%, respectively. The obtained specific activity was 2.17 U/mg. Kinetic studies of cellulase produced by C. globosum revealed 2.27 mg/ml as Km and 0.1194 µmol/ml/min as Vmax. Moreover, pH 5.0 and 65 °C were found to be optimum for the activity. Cellulase of C. globosum retained about 60 % of its activity when incubated at 65 °C for 2 h. Moreover, the enzyme showed high stability for pH 5 when incubated for 12h. An isoelectric point (pI) around 4.5 was detected for cellulase of C. globosum. The molecular weight was calculated to be about 40 KDa. The optimum temperature for the cellulase from T. reesei was 65 °C, while 60 °C was optimum for the xylanase activities of laminex and CWDEC. Cellulase from T. reesei retained about 85and 19% of the initial activity after 2 and 12 hours, respectively. While, laminex as cellulase retained 89 and 80% of the initial activity after 2 and 12 h incubation at its optimal temperature, respectively. pH 4.0 was favorable for the activity of the cellulase from T. reesei, and for laminex as cellulase. CWDEC as cellulase and xylanase exhibited the maximum activity at pH 3.0. All of the enzymes tested were stable for 12 h. when incubated at their pH optima. Application of cellulase, produced from C. globosum, on corn stover was assessed compared with cellulase from (T. reesei) , xylanase (A. niger and the UF), laminex and CWDEC enzymes. All enzymes gave higher concentrations of reducing sugars when corn stover was pretreated with peroxidase (MsP1) than untreated one. Laminex enzyme showed the highest catalytic activity to hydrolyze polymeric carbohydrates of corn stover. Maximum level of lignin degradation can be reached after 24 h. with using 3 units of MsP1. The highest amounts of reducing sugars were formed by laminex after pretreatment of corn stover with MsP1. On the other hand, the lowest yields of reducing sugars were obtained with Mn-P treated corn stover.