الفهرس 
MATERIALS AND METHODSOnly 14 pages are availabe for public view
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Abstract
Production of ethanol fermented from renewable sources for fuel or fuel additives are known as bioethanol. Bioethanol as a fossil fuel additive to decrease environmental pollution and reduce the stress of the decline in crude oil availability is becoming increasingly popular. The present study was investigated for production of bioethanol via fermentation of the soluble sugar produced by enzymatic saccharification of agriculture and agro-industrial wastes using the isolated cellulolytic soil fungi under solid state fermentation. The ethanolic fermentation of the soluble sugar was conducted by S. cerevisiae. Twenty fungal species were isolated, purified, identified and screened for their cellulolytic activities. Among of which sixteen fungal species showed cellulolytic activities. Out of the sixteen cellulolytic fungal species, Aspergillus terreus exhibited the highest producing to cellulase enzymes. A. terreus (MG811573.1) was identified according to microscopic morphological features and confirmed genetically by 18S rRNA gene. Among of the ten of agricultural and agro-industrial substrates, wheat bran and pineapple pulp were the most utilized by A. terreus for releasing reducing sugar. In determination of chemical composition of wheat bran and pineapple pulp before and after fermentation by A. terreus, the results revealed a decrease in cellulose, hemicellulose and lignin contents in the two fermented substrates. Fourier Transform- Infrared spectroscopy (FT-IR) of wheat bran and pineapple pulp before and after fermentation by A. terreus showed that bands were typically related to the structural characteristics of cellulose, hemicellulose and lignin which were diminished in the spectrum of wheat bran and pineapple pulp after fermentation. The results showed that the increasing in reducing sugar by A. terreus using treated wheat bran with 0.3% NaOH , while alkali- untreated pineapple pulp recorded highly concentration in reducing sugar. The results showed significant improvement in reducing sugar obtained by A. terreus cultivated on alkali- treated wheat bran and untreated pineapple pulp under the optimized conditions at incubation time 3 days, moisture level 30 and 20 ml, initial pH 5.2, incubation temperature 45°C, inoculum size 7×106 and 5×106 spores/10 g and inoculum age 9 and 7 days respectively. The results showed that the final values of reducing sugar were 233.78 and 515.10 mg/g for alkali- treated wheat bran and untreated pineapple pulp respectively. Molecular identification by 18s rRNA for selected yeast showed that the tested sequence had 99% similarity PCR sequence with their respective species, S. cerevisiae YGM1129, accession No: CP006378.1. The fermentation of hydrolysates of alkali-treated wheat bran and untreated pineapple pulp for bioethanol production using S. cerevisiae under optimized conditions as inoculum size 3×105 , inoculum age 24 hr, incubation period 24 hr, temperature 35ºC, pH 4.5 for alkali- treated wheat bran hydrolysate and pH 5 for untreated pineapple pulp hydrolysate using shaking condition, revealed an increase in ethanol production with good fermentation efficiency. The results recorded that the highest bioethanol production capacity by S. cerevisiae were 22.50 and 26.50 %( v/v) for alkali- treated wheat bran and untreated pineapple pulp hydrolysates respectively. FT-IR of purified bioethanol produced by S. cerevisiae from fermentation of alkali-treated wheat bran and untreated pineapple pulp hydrolysates showed that the presence of alcohol groups (OH, C-H and C-O). Gas chromatography analysis indicated that the purity of bioethanol were 99.191 and 99.539 % obtained from alkali-treated wheat bran and untreated pineapple pulp hydrolysates fermentation respectively and the purified of bioethanol contained lower quantities of volatile by-products. The quality of the resulting alcohol was compatible with the European Fuel Ethanol Standards.