Production of xylanase and itaconic acid (IA) from Aspergillus terreus NRRL 1960 from agricultural residues was investigated in this study. Two different media were tested and the medium having itaconic acid inducing capacity was chosen for further studies due to its high xylanase and IA production capacity. The best xylan concentration was found as 2% (w/v). Addition of commercial xylanase to production culture resulted in higher initial simple sugar concentration which increased IA production slightly but decreased xylanase production.
Among tested agricultural residues / corn cob, cotton stalk and sunflower stalk, the highest xylanase production was obtained on corn cob. Increasing the corn cob
concentration and applying wet heat pretreatment increased the xylanase production level. In a two-step fermentation process, 70000 IU/L xylanase production was achieved in a medium containing 7% wet heat treated corn cob followed by 17 g/L IA production in a medium containing 10% glucose.
Molecular weight and isoelectric point of xylanase were found as 19 kDa and pH 9.0, respectively. The enzyme was optimally active at 50° / C and pH 6.5-7.0. Kinetic experiments at 50° / C and pH 7.0 resulted in apparent Km and Vmax values of 2.5± / 0.05 mg xylan/mL and 50.2± / 0.4 IU/µ / g protein, respectively. The major products of birchwood xylan hydrolysis were determined by thin layer
chromatography as xylobiose and xylotriose. These findings indicate that the enzyme could be advantageous for use in different industrial applications due to its low molecular weight and its potential use for xylooligosaccharide production.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/3/12612067/index.pdf |
| Date | 01 June 2010 |
| Creators | Kocabas, Aytac |
| Contributors | Bakir, Ufuk |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | Ph.D. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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