TITLE

Low-cost carbon sources for the production of a thermostable xylanase by Aspergillus niger

AUTHOR(S)
Elias Pião Benedetti, Ana Cláudia; da Costa, Eliana Dantas; Aragon, Caio Casale; dos Santos, Andréa Francisco; Goulart, Antônio José; Attili-Angelis, Derlene; Monti, Rubens
PUB. DATE
January 2013
SOURCE
Revista de Ciências Farmacêuticas Básica e Aplicada;2013, Vol. 34 Issue 1, p25
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
A strain of the filamentous fungus Aspergillus niger was isolated and shown to possess extracellular xylanolytic activity. These enzymes have biotechnological potential and can be employed in various industries. This fungus produced its highest xylanase activity in a medium made up of 0.1% CaCO3, 0.5% NaCl, 0.1% NH4Cl, 0.5% corn steep liquor and 1% carbon source, at pH 8.0. A low-cost hemicellulose residue (powdered corncob) proved to be an excellent inducer of the A. niger xylanolytic complex. Filtration of the crude culture medium with suspended kaolin was ideal for to clarify the extract and led to partial purification of the xylanolytic activity. The apparent molecular mass of the xylanase was about 32.3 kDa. Maximum enzyme activity occurred at pH 5.0 and 55-60ºC. Apparent Km was 10.41 ± 0.282 mg/mL and Vmax was 3.32 ± 0.053 U/mg protein, with birchwood xylan as the substrate. Activation energy was 4.55 kcal/mol and half-life of the crude enzyme at 60ºC was 30 minutes. Addition of 2% glucose to the culture medium supplemented with xylan repressed xylanase production, but in the presence of xylose the enzyme production was not affected.
ACCESSION #
89186773

 

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