A requirement for the economically viable production of ethanol from lignocellulosic biomass is the development of efficient, low-cost processes for the enzymatic hydrolysis of cellulose and hemicellulose, as well as mild pretreatments to enhance the digestibility of the biomass with minimal losses of the polysaccharides. Another recent trend is the use of high initial concentrations of biomass, to reduce operational costs. Enzymes are responsible for a great share of the hydrolysis total costs, since high enzymatic loads must be used to attain acceptable yields. This is due to the inhibition of cellulases and xylanases by the hydrolysis products, which is intensified at high concentrations of biomass. Strategies to enhance the efficiency and reduce the costs of the enzymatic hydrolysis include: identification of more efficient enzymes (particularly those that are product-tolerant); enzyme engineering; statistical optimization of the production in low-cost media, and/or heterologous expression of efficient enzymes; formulation of efficient enzymatic cocktails; pretreatment with laccases for selective removal and/or redistribution of lignin. In this project, we will perform directed evolution studies of a glucose- and xylose-stimulated ß-glucosidase from Humicola insolens RP86, expressed in active form in E. coli by our group. We also aim the heterologous expression and the characterization of three enzymes recently identified by our group: an exo- and an endocellulase from Scytalidium thermophilum CBS 619.91 that are tolerant to cellobiose and glucose, and a glucose-tolerant ß-glucosidase from Chaetomium thermophilum. The working plan also includes: evaluation and optimization of the production of lignocellulolytic enzymes by mesophylic fungi in low-cost media; purification, biochemical and biophysical characterization of the enzymes with potential for biotechnological application; aminoacid sequencing, cloning and heterologous expression of the best enzymes. Our results may contribute to the knowledge of the structure-function relationship of cellulases and ß-glucosidases stimulated/tolerant to the products and to the identification/engineering of new enzymes with similar properties. Moreover, pretreatment processes using laccases and efficient enzymatic cocktails for the hydrolysis of lignocellulosic biomass may be developed. (AU)
Articles published in Agência FAPESP Newsletter about the research grant:
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
RODRIGUES SILVA, JEAN CARLOS;
SANTOS SALGADO, JOSE CARLOS;
VICI, ANA CLAUDIA;
WARD, RICHARD JOHN;
TEIXEIRA MORAES POLIZELI, MARIA LOURDES;
SOUZA GUIMARAES, LUIS HENRIQUE;
MELO FURRIEL, ROSA PRAZERES;
JORGE, JOAO ATILIO.
A novel Trichoderma reesei mutant RP698 with enhanced cellulase production.
Brazilian Journal of Microbiology,
Web of Science Citations: 0.