Genomic studies of global gene expression of Aspergillus niger grown on sugarcane bagasse and stem

Abstract

The dependence on fossil fuel sources as well as the concern about the environment has generated a worldwide interest in establishing new sources of fuel and energy. In this sense, the use of ethanol as a fuel is advantageous given its inexhaustible energy source and minimal environmental impact. Currently, Brazil is the world's second largest producer of ethanol, which is produced from sugar cane juice fermentation. However, several studies suggest that with the use of bagasse and straw, Brazil could double its production per hectare. Nevertheless, the use of this biomass presents a challenge, because is necessary to degrade plant cell wall structure (composed of complex sugars) into single fermentable sugar (such as glucose). To achieve this aim, several types of hydrolytic enzymes are required, that are produced by a variety of microorganisms. In this sense, Aspergillus niger is a fungus capable of producing and secreting those enzymes in large quantities. Although several studies have been performed with this microorganism, our understanding of the exact mechanisms of degradation of these substrates remains unclear. Therefore this project aims to analyze the global gene expression of A. niger cultivated on medium containing bagasse and stem from sugarcane as a substrate, by massively parallel high-throughput sequencing of cDNA (RNA-seq). Besides contributing to the understanding of biomass degradation, the knowledge on the molecular level resulting from this work will reflect on new perspectives for the development of enzyme cocktails, enabling the large-scale production of second-generation ethanol. (AU)