Production Physiology of Cellulases and β-glucosidase Enzymes of Aspergillus niger Grown under Solid State Fermentation Conditions

Abstract

A new isolate of A. niger F-119 was utilizaed to produce endoglucanase (EC 3. 21. 4) exoglucanase (EC 3. 2. 1. 91) and 13-glucosidase (EC 3. 2. 1. 21) adopting the solid state fermentation condition using radicle waste as main substrate. Cultural conditions including moisture level, incubation period, initial pH, incubation temperature and inoculum size were evaluated. The fungus expressed high enzymes production at moisture level 70% (w /w), initial pH 4.5, inoculum size 10% (v/w) at 32EC after 72h which yielded 31.5, 46.0 and 215.2 I U/g original sub st rate. Supplementation of the culture medium with ammonium sulphate (at a level of 20 mg N/g substrate) enhanced enzyme activities. Similarly, wheat bran at 20% (w/w) was the most suitable carbon source for o b taining high enzyme yields. Sucrose at level 1% (w/w) was found to be more effective for enzymes biosynhesis raising the enzymes levels to 59.2, 74.4 and 445 I U/g substrate of FPase, CMCase and $-glucosidase respectively. The distribution of the solid medium at 1.5 cm proved to be suitable for enzymes production wherein the process can be successfully repeated for four different cycles. Partial purification with ammonium sulphate showed that the protein fraction obtained at 20%-40% ammonium sulphate saturation was most suitable for enzymes recovery. The enzymes were found to be active and stable at temperatures 55, 65 and 60EC, p H 4.5, 5.5 and 4.5. The effect of treatment with different concentrations of sodium hydroxide on delignification of wheat straw substrate and thus enhancing the enzymatic hydrolysis of wheat straw was markedly accelerated after treatment with 4.5% NaOH solution. The partially purified 20-40% ammonium sulphate precipitate enzymes fraction and mouldy substrate were compared with crude enzyme extract to hydrolyze the alkali-treated wheat straw. The highest hydrolysis 82.8% was obtained using mouldy substrate. The enzymatic hydarolyzate containing 68% glucose of total sugars. The enzymatic hydrolyzate of the alkali-treated wheat straw was fermented for 48h by Saccharomyces cerevisiae and hybrid of S. cerevisiae has the ability to convert pentoses to enthanol 29.1 and 35.9 gram ethanol/100 g alkali-treated wheat straw were yielded by the two strains respectively.

Cellulases and animal feed production by solid-state fermentation by Aspergillus fumigatus NRCF-122 mutant

“…Vu et al [30] noted that substrate weight 3% is the most suitable percent when he used wheat bran to produce cellulase from Aspergillus niger . Fadel and Kahil [38] reported that 2% was the best, they used alkali treated cotton stalks for producing cellulose and hemicelluloses degrading enzyme by A. niger F-93 [39], as well as the same ratio was found by Fadel [39] when he produced xylanase from fermented sorghum flour by Trichoderma harizinum 418.…”

“…(NH4)2SO4 was used for cellulase production under solid state and submerged cultures from culturing many fungal strains i.e. Trichoderma harizianum, Penicillium funiculosum, Aspergillus niger, Fusarium dimerum and Rhizopus oryyzae [35,38,39,41].…”

Enhanced Production of β-glucosidase by New Strain Aspergillus protuberus on Solid State Fermentation in Rice Husk

“…on combination of CH 3 COONH 3 0.35%, (NH 4 ) 2 SO 4 0.7% and KH 2 PO 4 0.4%. Introduction of ammonium sulphate at 2% N (w/w) enhanced extracellular soluble protein/g of substrate by A. niger in comparison to control by about 13.6% (Fadel 2000). This increase in soluble proteins was accompanied by increase to the extent of 21.3, 21.5 and 20% in the activity of FPase, CMCase and β-glucosidase respectively.…”

“…The optimum temperature 32 o C was recorded for the maximum production of cellulolytic enzymes by A. niger F-119 on radicle wastes (Fadel 2000). Badhan et al, 2007 showed that the incubation temperature at 45 o C was found to be optimum for production of cellulolytic enzymes by Myceliophthora sp.…”

Exoglucanase production by Aspergillus niger grown on wheat bran

“…Virtually, information on the effect of thickness of bed of solid medium on enzyme production in SSF is lacking. The influence of depth of solid medium on production of cellulolytic enzyme by A. niger in SSF has been assessed (Fadel 2000). According to this study, production of cellulases and β-glucosidases by A. niger on radicle waste increased slightly until 12 mm, was steady to 18 mm, and then decreased.…”