Biotechnological studies on biofuel production from agricultural wastes

Four different fruits peels (Banana, Watermelon, Orange and Mango) were chosen to study the possibility to produce biofuel. The starch, pectin, hemicellulose, celluloses, lignin and proteins fractions were determined in terms of dry weights percentages for these peels. The obtained results showed that mango peels recorded the highest oligosaccharides levels, even lignin content was highest by 17.25%. Also, banana peels showed high oligosaccharides levels, with the lowest level of lignin by 4.82%. Aspergillus niger and Phanerochaete chrysosporium were used to degrade fruit peels , where during their degrading enzyme assays the co-cultivation can improve extracellular enzyme secretion. While, the co-cultivation was resulted an increasing in enzymes activities by 5.8, 8.8 and 81.3 nmol.min-1.ml-1 for β-glucosidase, celulase and xylanase, respectively. The SDS-PAGE protein profiles confirmed that, fungi co-cultivation results in improved the excretion of relevant enzymes proteins, the combined profile were contained proteins not observed in the individual fungus culture. The banana and mango peels were released the greatest saccharified pentose and hexose sugars, the total fermentable sugars from them were 27.77 and 21.13 g.l-1, respectively. The co-fermentation were conducted by selected yeast strain belong to Kluyveromyces marxianus to contribute previously sexual regenerative Saccharomyces cerevisiae for bioethanol production. As expected, the co-fermentation increased the bioethanol yield by more than 18% as average percentage for all saccharified peels. The substantial bioethanol yield were observed by saccharifed banana peels with 10.74 g.l-1, the adding of calcium oxide as drying agent lead finally to 97.5 wt % of pure bioethanol by duplicate the distillation process. The reaction molar ratio of cocked oil to ethyl acetate were established by 0.1, 0.125, 0.2, 0.25, 0.5 and 1.0 mol.mol-1 respectively.