Effect of cultivation pH and agitation rate on growth and xylanase production by Aspergillus oryzae in spent sulphite liquor
| Autor: | Lew Christopher, James C. du Preez, Zawadi A. Chipeta |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Aspergillus oryzae
Bioengineering Cellulase Raw material Applied Microbiology and Biotechnology Acetic acid chemistry.chemical_compound Bioreactors Water Movements Extracellular Bioreactor Sulfites Food science Endo-1 4-beta Xylanases biology Hydrogen-Ion Concentration biology.organism_classification Xylan Culture Media Xylosidases chemistry Biochemistry Xylanase biology.protein Xylans Biotechnology |
| Zdroj: | Journal of Industrial Microbiology & Biotechnology. 35:587-594 |
| ISSN: | 1476-5535 1367-5435 |
| Popis: | The effects of cultivation pH and agitation rate on growth and extracellular xylanase production by Aspergillus oryzae NRRL 3485 were investigated in bioreactor cultures using spent sulphite liquor (SSL) and oats spelts xylan as respective carbon substrates. Xylanase production by this fungus was greatly affected by the culture pH, with pH 7.5 resulting in a high extracellular xylanase activity in the SSL-based medium as well as in a complex medium with xylan as carbon substrate. This effect, therefore, was not solely due to growth inhibition at the lower pH values by the acetic acid in the SSL. The xylanase activity in the SSL medium peaked at 199 U ml(-1) at pH 7.5 with a corresponding maximum specific growth rate of 0.39 h(-1). By contrast, the maximum extracellular beta-xylosidase activity pf 0.36 U ml(-1) was recorded at pH 4.0. Three low molecular weight xylanase isozymes were secreted at all pH values within the range of pH 4-8, whereas cellulase activity on both carbon substrates was negligible. Impeller tip velocities within the range of 1.56-3.12 m s(-1) had no marked effect, either on the xylanase activity, or on the maximum volumetric rate of xylanase production. These results also demonstrated that SSL constituted a suitable carbon feedstock as well as inducer for xylanase production in aerobic submerged culture by this strain of A. oryzae. |
| Databáze: | OpenAIRE |
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