INCT 2014: National Institute of Science and Technology of Bioethanol

Abstract

During the second phase of the INCT-bioethanol we intend to integrate the knowledge obtained during the last 6 years to assemble enzyme consortia that will hydrolyze the cell walls of sugarcane quickly and efficiently. The main focus will be to design enzyme consortiums that can be used to hydrolyze diverse sugarcane biomasses as well as genetically and chemically transformed varieties. The aim is to define combinations of enzymes that can improve the hydrolysis process by identifying different patterns of correspondence between variations in cell wall composition and different enzyme consortia. The consortia will be assembled from the 70 or so different hydrolases available in the INCT collection. In order to achieve this integration, a high throughput saccharification system will be employed to run analyses initially with commercial enzyme cocktails. Samples with different levels of sugarcane biomass saccharification will be further analyzed in order to understand the relationship between the cell wall chemical variability and degree of hydrolysis. This will enable the identification of cell wall-related genetic markers that can be used to enhance existing varieties and direct the search for new varieties of sugarcane. Simultaneously, genes encoding cell wall hydrolases will be silenced or activated using an INCT collection of genes present in the genome of sugarcane. Manipulating these genes, will be possible to evaluate the respective impacts of hydrolysis on three major limiting factors to hydrolysis: porosity, glycomic code and macrofibrilar structure of biomass. The objective is to produce, in the long term, sugarcane plants that display internal mechanisms designed to facilitate hydrolysis, possibly coupled with controlled activation mechanism that induce plants to express specific hydrolases. The implications of gaining the knowledge to control the composition and turnover of cell walls go beyond the development of technologies for ethanol production. By controlling the process of cell wall formation and deposition, possibilities such as the use of sugarcane mills as true biorefineries become feasible. One example is the impact that the use of lignans or hemicellulosic polysaccharides, such as glucan and xyloglucan, may have on their use as food additives, in cosmetics and for medical applications. Therefore, the knowledge that will be produced by the INCT-bioethanol in this second phase will significantly strengthen the Brazilian position as a developer of novel biomaterials-based products further elevating the sustainability of the sugarcane system. It should be emphasized that the consolidation of procedures resulting in high efficiency hydrolysis in sugarcane will have a positive impact in the development of this type of process in other parts of the world, since cell walls of other grasses used for bioenergy production (e.g. maize, rice, sorghum and miscanthus) are in many ways similar. For this reason, this project will strengthen the Brazilian strategic goal to achieve a leading position as an exporter of 2G technologies to other countries. It is noteworthy that the INCT-bioethanol, already has the information to design strategies for sugarcane engineering to produce cell walls that are more amenable to hydrolysis. This type of technology opens the way for the engineering of other grasses of significant agronomic value. (AU)