الفهرس | Only 14 pages are availabe for public view |
Abstract Lactose hydrolysis and production of ethanol as a biofuel was evaluated and conducted in the present study. Lactose was hydrolyzed by Candida pseudotropicalis and Kluyveromyces fragilis that grown in whey and synthetic medium. In addition, optimum pH and optimum incubation temperature for lactose hydrolysis were studied and were found 3 and 37ºC respectively in Candida pseudotropicalis, while it were 5.1and 35ºC respectively in Kluyveromyces fragilis. On the other hand, two isolates and one strain of Saccharomyces cerevisiae were tested to produce ethanol from hydrolyzed whey. The current study shows that the strain was more effecciency in bioethanol production with level reached to 1.21% (v/v). Moreover, protoplast fusion was done between lactose fermenting Candida pseudotropicalis and lactose nonfermenting Saccharomyces cerevicae and the fusion process gave rise to new hybrid yeast. The recombinants showed growth on lactose in whey and synthetic medium. (The ethanol yields by some recombinants were reached 3.27%, 2.24%, 2.10% and 2.06% from whey medium and 2.54%, 2.00%, 1.88% and 1.65% in synthetic media). Also the conversion of glucose that released from lactose hydrolysis by Candida pseudotropicalis into fructose via addition of immobilized glucose isomerase has been carried out and fructose content was 65.21 mg/100ml. In addition antimicrobial activities of whey proteins against the tested microorganisms (E. coli, Staphylococcus aureus & Listeria monocytogenes) were assayed by evaluating the inhibition zones diameters. The highest inhibition zone was recorded for E. coli (10mm) followed by Staphylococcus aureus(9mm) while there was no detectable effect on Listeria monocytogenes. Keywords: Bioethanol, Fructose syrup, Galactose, Glucose isomerase, Lactose, Protoplast fusion, Whey, Whey antimicrobial activities, Candida pseudotropicalis, Kluyveromyces fragilis, Saccharomyces cerevicae. |