الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 273 |  |  |
| | | from | 273 | | |
Abstract
In the present study, thirty-one isolates were collected from different locations in Tanta city, Gharbia Governorate, Egypt. These isolates were screened for their polyvinyl alcohol (PVA)-degrading ability as a sole carbon source in the culture medium. Among the thirty-one tested isolates, only Seventeen isolates were found to be PVA degraders belonging to genera Penicillium, Aspergillus, Trichoderma, Fusarium and Ulocladium. The highest degradation percentages were recorded for P. polonicum ON024147 (25.7%) and A. niger ON012795 (24.28%). The most suitable molecular weight of PVA can be easily degraded by the both selected fungi was in range between 13 and 23 KD. The PVA-degrading enzymes were screened for the two fungi and it was discovered activities for PVADH, OPH, cellulase, lipase and catalase enzymes. The culture conditions were optimized for maximum PVA-degradation of 88% and 90% by P. polonicum and A. niger, respectively. The optimum static culture conditions for P. polonicum were adjusted at pH 5 and incubation at 30°C for 6 days in the presence of starch as a co-carbon source and KNO3 as a nitrogen source with PVA conc. 10 g/L. For A. niger, the optimum growth conditions were at pH=6, 30°C, static culture, for 6 days, cellulose as a co-carbon source, sodium nitrate as a nitrogen source and PVA conc.= 10 g/L. In the meantime, the optimized conditions of cellulase and lipase activities were studied. The optimum conditions for cellulase production were pH 5, at 30°C, 6 days incubation, carboxy methyl cellulose (CMC) as a co-carbon source with 1% PVA concentration as a substrate for both fungi. While the best nitrogen sources were KNO3 and Sodium nitrate for P. Polonicum Abstract 11 and A. niger, respectively. Lipase production was optimized at pH 6, 30°C for 6 days of incubation, starch (co-carbon source) and ammonium sulphate (nitrogen source) for both fungi.