Abstract
An extracellular low-molecular mass component (LMMC) with catalytic properties was isolated from liquid cultures containing wheat bran of ascomycete thermophilicThermoascus aurantiacus.The partially purified LMMC showed very high activity with typical phenoloxidase substrates in the absence of hydrogen peroxide at acidic pH (2.8). However, in this pH range, the phenoloxidase (PO) activity was quickly lost. The LMMC showed a high optimum temperature (80°C) and an elevated thermostability. The molecular mass of the component estimated by gel filtration chromatography was 530 Da. IR and1H- and13C-NMR spectra indicated the presence of hydroxamic acid moiety. Qualitative determination of metal ions by several techniques revealed the presence of mainly iron associated with this structure. Iron may be the responsible for the ability for catalyze oxidation reactions, such as o-dianisidine oxidation, by the LMMC. These results suggested the existence of a hydroxamate-type metal-binding component, most likely hydroxamate siderophore. In addition, the chrome azurol S (CAS) universal assay for noncomplexed siderophores detection revealed the production of these compounds byT.aurantiacusin solid and liquid media.
Published Version
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