Abstract
The use of residual lignocellulosic material from different agro-industrial processes as feedstock for the bioethanol production has been an energy alternative in the world due to its wide availability and low cost, which has posed major challenges in the processes of microbial fermentation of hexoses and pentoses (products available after hydrolysis of lignocellulosic material). The fermentation of pentoses (xylose and arabinose) is still a wide field of study. In this research, Colombian native bacteria able to transform xylose into ethanol were isolated and identified. Selected strains were identified by amplification and analysis of the 16S rRNA gene, and results showed they are related to members of genera such as Airebacillus sp., Bacillus sp., Lysinibacillus sp., Enterococcus sp., and Citrobacter sp. The isolated strains were characterized for the xylose and glucose consumption and product formation. The measured ethanol yield was in a range between 0,006 – 0,174 g ethanol/g sugar in xylose after 48 h. In a mixture of glucose and xylose, the results showed that the ethanol yield was in a range between 0,010 – 0,092 g ethanol/g sugar, and both substrates were consumed. Organic acids were obtained as fermentation product, which is a feature of these strains. The co-fermentation of xylose and glucose that was evidenced in the metabolism of the isolates represents an alternative for the transformation of the hemicellulosic fraction of agroindustrial wastes.
