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Poster Presentation 3-35
An Alternative Approach for Utilization of the Pentose Stream from Sugarcane Bagasse by an Induced Flocculent Pichia stipitis
Heizir F. de Castro1, Sandra A Furlan2 and Samuel C. Oliveira2
1Faculty of Chemical Engineering of Lorena PO Box 116, Lorena, São Paulo 12600-970 Brazil
2UNIVILLE, PO Box 1361, 89201-972, Joinville SC Brazil
3Department of Biotechnology, Faculty of Chemical Engineering of Lorena
Telephone: +55-12-5533224; Fax: +55-12-5533224; E-mail: decastro@easygold.com.br
Research and development studies of alcohol fermentation technology have been conducted over the last decades to make alcohol production more efficient. In this context there are clear advantages in using surplus bagasse from ethanol plants as a raw material for the same end product. The alcohol fermentation of pentose has become an attractive research topic and publications are numerous. However, a suitable process technology has not been established to date.
This study investigated the feasibility of using hemicellulosic hydrolyzate to dilute the conventional raw material (sugarcane juice) to a standard sugar concentration employed for the industrial production of ethanol. The resulting sugar mixture (150 g/L) was used as the substrate to evaluate the performance of a continuous reactor incorporating a cell recycle module, operated at several dilution rates. An induced flocculent pentose-fermenting yeast strain (Pichia stipis) was used for this bioconversion. Under these conditions, the reactor performance was satisfactory at substrate feed rates of 30 g/L/h or less, corresponding to an ethanol productivity of about 11 g/L/h and an overall sugar conversion above 95%.
The results showed real advantages over existing alternatives for a better exploitation of surplus bagasse to increase industrial alcohol production. Moreover, this process has a potential use for: 1) attaining high ethanol levels; 2) avoiding treatment for removing inhibitory compounds normally found in the hemicellulosic acid hydrolyzate; 3) decreasing the addition of microbial nutrients; and 4) requiring minimal changes on ethanol plants for its implementation, i.e., substitution of the yeast genus S. cerevisiae by P. stipitis. However, a successful application of this approach is limited by the implementation of an adequate dilution rate in the reactor in order to achieve an efficient pentose conversion. Optimization of the dilution rate is currently the primary objective for further developments of this technology.
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