The properties of Trematosphaeria mangrovei laccase enzyme purified on Sephadex G-100 column were investigated. SDS-PAGE of the purified laccase enzyme showed a single band at 48 kDa. The pure laccase reached its maximal activity at temperature 65 °C, pH 4.0 with K m equal 1.4 mM and V max equal 184.84 U/mg protein. The substrate specificity of the purified laccase was greatly influenced by the nature and position of the substituted groups in the phenolic ring. The pure laccase was tested with some metal ions and inhibitors, FeSO4 completely inhibited laccase enzyme and also highly affected by (NaN3) at a concentration of 1 mM. Amino acid composition of the pure enzyme was also determined. Carbohydrate content of purified laccase enzyme was 23% of the enzyme sample. The UV absorption spectra of the purified laccase enzyme showed a single peak at 260-280 nm.
Four different Aspergilli (Aspergillus oryzae, A. parasiticus, A. terreus and A. versicolor) were grown on wheat grains underdifferent degrees of relative humidity 14, 50, 74, 80 and 90%. Samples of wheat grains were taken monthly for a period of six months and examined for mycotoxin production. A. oryzae was found to produce aflatoxins B1, B2, zearalenone, DON and T-2 toxins under elevated degrees of humidity and prolonged periods of storage. A. parasiticus produced aflatoxins B1, G1, NIV, DON and T-2 toxins in high concentrations during a period of not more than three months storage at 14% relative humidity; at an increased level of relative humidity of 74% ochratoxin A, zearalenone and sterigmatocystin were also produced at high levels. The isolate was drastic in toxin production. A. terrus produced toxins at 14% relative humidity (aflatoxin G2 and DON) at levels much higher than any other prevalent degrees of humidity. A. versicolor is highly sensitive to relative humidity and grain moisture content It produced aflatoxins B1, G1, NIV and DON at a relative humidity of 50% and another toxins (aflatoxin G2, ochratoxins A, B and zearalenone) at 74%. The microorganism can be considered a trichothecene producer under suitable relative humidity.
Eleven fungal strains were tested for their ability to produce brown and reddish brown textile dyes using H-acid (1naphthol-8-amino-3, 6-disulfonic acid) as a dye precursor in the fermentation medium. All tested fungal strains exhibited high ability to produce dyes varying in both dye color (brown to reddish brown) and fastness properties to washing, perspiration and UV light. The produced dyes were subjected to further analysis for quantitative determination of dye components for investigation of their interrelations as well as their role in dye color and stability.
Chemical analysis of corn steep liquor, produced from wet milling of corn grains, revealed the presence of 0.3% total sugars and 1.0% proteins. Aspergillus terreus was found to be the most highly active organism, rapidly converting about 78.57% of the total sugars into fungal mass (24.2 g/l) with 41.65% proteins. Biochemical oxygen demand was reduced by 87.81%.
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