Monday, May 4, 2009
5-40
A Study of Cellulases Production by Filamentous Fungi Strains using Experimental Design
Ethanol is recognized as one of the most important renewable fuels due to the economic and environmental benefits of its use. Agro-industrial residues and forests are the most promising raw materials to be converted in ethanol. This transformation is mediated by an enzymatic complex entitled cellulases. There are theories suggesting that three cellulases act synergistically hydrolyzing the cellulose of pretreated lignocellulosic materials into glucose that is used for ethanol production. Embrapa Food Technology team is studying the screening of filamentous fungi strains isolated from different biomes with the aim of identify the best cellulase producers. Two filamentous fungi: 3T5B8, a mutant strain and PIP, a wild strain, were selected. In this work, the effects of process variables on cellulose production by two strains have been studied in aerated column by experimental design. The fractional factorial method using the Plackett-Burman design was studied investigating six variables: temperature, aeration, humidity and the concentration of cellobiose, nitrogen and inoculum. Fifteen grams of sterilized medium using wheat brain and the composition designed by the method were inoculated in each aerated column. After 48 h of fermentation, each column was taken for enzyme extraction with citrate buffer pH 4.8. The best results in enzymatic activity were obtained for PIP strain: Carboxymethylcellulase (326 U/gds), FPase (8 U/gds) and beta-glucosidase (409 U/gds). A new experiment has been carried out with a third selected strain of filamentous fungus. The study of the significance of the available variables in the cellulases production will still be concluded.
Financial support: Embrapa-MP1
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