الفهرس 
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Abstract
Bioethanol is by far the most widely used biofuel for transportation worldwide. Production of bioethanol from biomass is one way to reduce both consumption of crude oil and environmental pollution. Bioethanol can be produced from different kinds of raw materials. These raw materials are classified into three categories of agricultural raw materials: simple sugars, starch and lignocellulose. The price of the raw materials is highly volatile, which can highly affect the production costs of the bioethanol. One major problem with bioethanol production is the availability of raw materials for the production. Lignocellulosic biomass is the most promising feedstock considering its great availability and low cost, but the large-scale commercial production of fuel bioethanol from lignocellulosic materials has still not been implemented. (Mustafa, 2011).
The objective of this study included: isolate and identify of some cellulolytic fungi from different agriculture wastes, study their enzymatic activity to saccharification of rice straw and the use of the produced sugars for bio-ethanol production.
Result could be summarized in the following point:
1- Twenty four cellulolytic fungi were isolated from mature compost, immature compost and rice straw, being 8, 7 and 9 fungal cultures, respectively. The fungal isolates were picked up from plates containing carboxy methyl cellulose (CMC) and rice straw as a sole source of carbon. Two known cellulase producing fungal strains Trichoderma viride c34 from NRC (National Research Center), Doki, Giza Governorate and pure culture of Trichoderma viride, given name (1002) was obtained form Agric. Microbiology Department, Faculty of Agriculture Ain Shams University were also used for comparison study.
2- The isolates were identified according to their morphological and taxonomic characteristics. Data clearly showed that the fungal cultural belonged to the genera Aspergillus, Trichoderma and Rhizopus.
3- Cellulase activities of fungi isolates was achieved by using carboxy methyl cellulose (CMC) selective agar medium for selecting the most active cellulase-producing isolates. Only 15 isolates showed decolorization zone around mycelial growth.
4- Three fungal isolates Aspergillus flavus (2103), Trichoderma viride (4114) and Aspergillus niger (2207) and two known cellulase producing fungal strains Trichoderma viride c34 and Trichoderma viride. (1002) as reference strains were selected according to their efficiency to hydrolyze CMC to evaluate cellulase activity and Filter Paper Activity (CMCase and FPase) assay. The correlation coefficient between enzyme activity and mycelium dry weight revealed that a positive R was recorded being 0.0596 for CMCase and 0.7245 for FPase.
5- Eight different pretreatments of rice straw were studied as a sole carbon source in hydrolysis media to produce fermentable sugars using shake flask as batch culture. The pretreatments rice straw were chipping to 10-30 mm, milling to 0.2-2 mm, Steam explosion, alkali pre-treatment by 2% NaOH, acid pre-treatment by 1% sulfuric acid, oxidative pre-treatment by 1% H2O2, grinding together with alkali pre-treatment by 2% NaOH and grinding together with acid pre-treatment by 1% sulfuric acid
6- Five fungal strains were tested in solid state fermentation for their ability to saccharification of different pre-treated rice straw to study their efficiency to produce fermentable sugars. The reducing sugars produced from the pretreated rice straw by cellulolytic fungal strains increased gradually with elapsing of time and reached their maximum on the 4th day for Trichoderma viride c34,Trichoderma viride (1002) and Trichoderma viride (4114) whereas the highest values of reducing sugars were recorded on 2nd of incubation for Aspergillus flavus (2103) and Aspergillus niger (2207). The highest values of reducing sugars recorded by Aspergillus flavus (2103) followed by Trichoderma viride c34 were 1.863 and 1.230 (g/l) respectively. Results depicted that grinding plus 1% sulfuric acid was the best pretreatment for all tested cellulase producing fungal strains where the decomposition rate of rice straw ranged from 57.3 to 66.7%.
7- Concerning shake flask fermentation, hydrolysis by Aspergillus flavus (2103) showed the maximum reducing sugars after 2 days using grinding plus (1%) sulfuric acid pretreatment being 1.667 (g/l).
8- Factors affecting the reducing sugar productivity by cellulase producing fungi showed that the optimum pH, temperature and inoculum size for producing the highest fermentable sugars were 5.0-5.5, 25-30° C and 4-5% respectively
9- Fermentation of sugar solution obtained from enzymatic hydrolysis of rice straw by Saccharomyces cerevisiae SHF-5 showed that about 5.1% (v/v), 0.478% (v/v) of alcohol in the fermented solution was achieved after 32 hrs of incubation.
10- The utilization of rice straw for production of bioethanol will participate in the recycling of this waste (approximately 3.5 million ton / year in Egypt) to valuable substances and consequently lead to reduce CO2 produced from the burning of rice straw which causing global warm. On the other hand the utilization of rice straw for ethanol production will be ecofriendly.