الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 302 |  |  |
| | | from | 302 | | |
Abstract
Agro-industrial wastes comprise plant residual material generated by processing, such as peels, shells, husks, skins, stems, stones, exhausted pulp and other parts of the plant material not intended for food production. Lignocellulosic represent the main component of these wastes. Conversion of these wastes into high-added value chemicals such as bioethanol, single cell protein and other chemicals included successive steps. Production of enzymes which are responsible for lignocellulosic hydrolysis represent the most important step in this process.
1. In this work, nineteen fungal strains were screened for their ability to produce cellulases and hemicellulase enzymes under submerged fermentation technique at different incubation periods by using cellulose and corncobs xylan as a sole and individual carbon source and inducer. Synchatrium endobioticum produced the highest cellulases activities (CMCase and FPase); A.niger produced the highest cellobiase activity, F. moniliforme and P. chrysogenum produced highest hemicellulose activity.
2. The optimization of medium composition is done to maintain a balance between the various medium components in production media which is done for commercial practice. Optimization helps minimizing the amount of undesirable components at the end of fermentation. In this work, numbers of factors were optimized. These factors can be summarized as follows:
• Different concentrations of cellulose and corncobs xylan. The highest FPase (110U/l) and CMCase (915U/l) were exhibited by S. endobioticum as it was grown on medium comprising 6g/l cellulose. hemicellulase values 5618U/l were showed by F. moniliforme.While,the maximal productivity of hemicellulose was reached to 5814U/l at 10g/l in case of P. chrysogenum.
• Different nitrogen sources (different sources of organic nitrogen, as well as inorganic ones) were tested. Control nitrogen source (yeast extract) exhibited the highest enzymes productivities of tested fungal strains.
• Different concentrations of yeast extract. The highest FPase (156.03U/L) and CMCase activities (1622.85U/L) showed by using 4g/L yeast extract. Similarly, P. chrysogenum and F. moniliforme exhibited their highest hemicellulase activities 8196.29U/l and 8074.04U/l by using 4g/l yeast extract, respectively.
• Effect of inorganic salts was tested; S.endobioticum and F. moniliforme were needed for all of the tested inorganic salts to exhibit its own higher activity. On the other hand amongst various inorganic salts, P. chrysogenum needed (only) KH2PO4 to for highest production hemicellulase activity.
• Effect of different pH values, tested fungal strains showed highest enzymes activities on pH 5.
• Effect of inoculum size on cellulase and hemicellulase …activities of the selected fungal strains. Control …inoculum size (4%) was needed for all fungal strains to …show their highest enzymes productivity.
• Effect of agitation speed on cellulase and hemicellulase activities of the selected fungal strains. Control agitation speed (150 rpm) was needed for all fungal strains to show their highest enzymes productivity.
• Effect of incubation temperature on the cellulolytic and hemicecellulolytic activities of the selected fungal strains. Control incubation temperature (30oC) was needed for all fungal strains to show their highest enzymes productivity.
• Effect of supplementation, of the used medium, with some additives, on cellulolytic and hemicellulolytic activities of the selected fungal strains. By using Tween 80 (3ml/l) the fungal isolates S.endobioticum exhibited a limited increase in its CMCase value (1910.35U/l) accompanied by a slight decrease in its FPase activity (192.52U/l) as compared to the control figures. On other hand, slight changes in culture filtrate protein levels were recorded with these additives. Furthermore, the supplementation with any of the aforementioned additives had not any noticeable effect on the hemicellulase activities of P. chrysogenum and F. moniliforme. Thus, no additives were used in the next experiment.
3. Analytical characterization and chemical pretreatment of some agro-industrial wastes included the stems, the leaves, the roots of tomato plants and a pomace resulted as a waste of tomato juice industry. The other AIW included beet bagasse, resulted as a by-product of sugar industry, in addition to the oil cakes of olive, sesame and wheat germ.
Total lipids, total ash, lignin, hollocellulose, cellulose, hemicellulose and crude protein were determined on dry weight basis.
4. Attack of the pretreated AIW by the selected fungal strains.
5. Preparation and partial purification of fungal cellulase and hemicellulose was done by using bulk precipitation by 70% acetone. The specific activities (of crude preparation) of FPase, CMCase, cellobiase and hemicellulase were found: 1.70, 17.00, 1.80 and 67.14 IU/mg protein, respectively.
6. Saccharification of pretreated AIW by partially purified cellulase and hemicellulose, the highest S.P. values were recorded with wheat germ oil cake (100% saccharification), beet bagasse (91.11% saccharification) and Tomato pomace (88.88% saccharification) as they were attacked by the mixed enzymes at the relatively lower E/S ratios for 48 h.
7. Production of bioethanol and single cell protein (SCP) from saccharified sample of the selected AIW. wheat germ oil cake showed almost complete conversion (97.8% of the theortical yield of bioethanol) as it was fermented with each of the two microorganisms, Also, the saccharified sample of beet bagasse and tomato pomace exhibited the same yield of bioethanol (97.8% of theortical yield) as they fermented with Z.mobilis NRRL b-1960. On other hand, fermentation of each of the saccharified beet bagasse and tomato pomace with S.cervicae led to relatively lower bioethanol yield: 85% and 60 %( of theortical yield), respectively. The results indicated that the higher cells yields (68g/l and 52g/l) of S.cervisae and Z.mobilis, respectively, were produced as they were grown, separately, on the hydrolysate of wheat germ oil cake. On other hand, the lower cell yield (28.4 g/l and 11.6g/l) were shown by Z.mobilis as it was grown separately on beet bagasse and tomato pomace, respectively. Growing S.cervicae on the hydrolysates of beet bagasse and tomato pomace separately, it offered moderate cell yields (56.00g/l and 54.00g/l), respectively.