Solid Substrate Fermentation Of Rice Straw By Trichoderma viride IBRL-TCS06 For Fermentable Sugars Production

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Date
2011-05
Authors
Teoh, Chai Sin
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Publisher
Universiti Sains Malaysia
Abstract
The research focused on the production of fermentable sugars in solid substrate fermentation (SSF). The potential use of rice husk and rice straw as substrates were used to screen for potential microorganism that capable of producing fermentable sugars under SSF. Five types of fungi were used, namely Aspergillus niger USM AI-I, A. niger USM AI-II, A. niger USM AI-F4, Trichoderma viride IBRL-TCS06 and Phanerochaete chrysosporium, either as a single or mixed cultures. Results showed that Trichoderma viride IBRL-TCS06 was efficient in degrading rice straw and producing the highest fermentable sugars approximately 18.13 ±0.67 mg/g substrate with the fungal growth of 1.46±0.08 mg glucosamine/g substrate under condition of 5 g of 0.75 mm substrate, 80% (v/w) moisture content and 1x106 spores/ml for 1 week at room temperature (28±2°C). The cellulase, xylanase and mannanase activities were 20.35±0.72 U/g substrate, 47.30±0.68 U/g substrate and 5.47±0.56 U/g substrate, respectively. Mixed culture cultivation resulted in lower cellulase, xylanase and mannanase activities as well as fermentable sugars production compared to individual or mono-culture. Pretreatment was desirable to achieve the highest yield of fermentable sugars from holocellulose with the goals to decompose the polymeric components of the straw and form sugar monomers, enhance enzymatic conversion of the cellulose fraction. The best results of the pretreatment on rice straws were achieved with 1.5% KOH (w/v), 30.33±1.04 mg fermentable sugars/g substrate and growth of 1.59±0.08 mg/g substrate. Characterization of the physical and chemical parameters for maximum fermentable sugar production were carried out with additional of 0.6% (w/w) of (NH4)2SO4 an d 0.5% (w/w) of CaCl2.2H2O, inoculums size of 1x105 spores/ml without mixing. Results showed that T. viride IBRL-TCS06 able to produce about 43.35±1.87 mg/g of fermentable sugars with growth of 2.47±0.10 mg glucosamine/g substrate after 6 days of cultivation.
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Keywords
The production of fermentable sugars , in solid substrate fermentation
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