Fusarium sp. has been shown to be a promising organism for enhanced production of xylanases. In the present study, xylanase production by 21 Fusarium sp. isolates (8 Fusarium culmorum, 4 Fusarium solani, 6 Fusarium verticillioides and 3 Fusarium equiseti) was evaluated under solid state fermentation (SSF). The fungal isolate Fusarium solani SYRN7 was the best xylanase producer among the tested isolates. The effects of some agriculture wastes (like wheat straw, wheat bran, beet pulp and cotton seed cake) and incubation period on xylanase production by F.solani were optimized. High xylanase production (1465.8 U/g) was observed in wheat bran after 96 h of incubation. Optimum pH and temperature for xylanase activity were found to be 5 and 50°C, respectively.
Fungi are well known for their ability to excrete enzymes into the environment. The fungal isolate FSS60 was the best amylase producer among one hundred and thirty-six isolates obtained from Syrian soils and tested for amylase production. According to the sequence of the internal transcribed spacer (ITS) rDNA gene, the isolate was identified as Aspergillus flavus. Optimal initial pH for amylase production was found to be 9.0. The enzyme was optimally active at 50°C and pH 5.0.
The restriction of PCR-amplifïed internal transcribed spacers (ITS) of ribosomal DNA was used to confirm the genetic variation among 22 isolates of Cochliobolus sativus differing in their xylanase production. Results show a high level of diversity of ITS-RFLP markers among the isolates. The molecular parameter used showed that C. sativus isolates reside in three phylogenetic groups. There was observed the resolution between clustering of isolates and their xylanase production level.
Random amplified polymorphic DNA (RAPD) analysis was used to evaluate genetic diversity among 13 soil Pénicillium strains originating from widely dispersed areas. Twenty one of the 34 synthetic random primers were found to identify polymorphism in amplification products. The results show a high level of diversity of RAPD markers among the strains. All the strains could be identified by their characteristic amplification profile, using selected random primers. This suggests that RAPD analysis is a useful and reliable assay for characterizing the species of Pénicillium genus.
Xylanase production by a newly isolated Aspergillus niger SS7 was studied in submerged culture. The optimum initial pH for xylanase production was found to be 7.0. Different agricultural and industrial wastes were evaluated for their ability to induce xylanase production by this isolate. The best xylanase production (293.82 IU/ml) was recorded at 3% (w/v) corn cob hulls after 120 h of incubation. The Aspergillus niger SS7 isolate grown in a simple medium, proved to be a promising microorganism for xylanase production.
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