Effects of pretreatment on morphology, chemical composition and enzymatic digestibility of eucalyptus bark: a potentially valuable source of fermentable sugars for biofuel production - part 1

Autor(es):Mostrar menos -

Lima, Marisa A. ^[1] ; Lavorente, Gabriela B. ^[2] ; da Silva, Hana K. P. ^[2] ; Bragatto, Juliano ^[2] ; Rezende, Camila A. ^[1] ; Bernardinelli, Oigres D. ^[1] ; deAzevedo, Eduardo R. ^[1] ; Gomez, Leonardo D. ^[3] ; McQueen-Mason, Simon J. ^[3] ; Labate, Carlos A. ^[2] ; Polikarpov, Igor ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

^[2] Univ Sao Paulo, Dept Genet ESALQ, Lab Max Feffer Genet Plantas, BR-13418900 Piracicaba, SP - Brazil

^[3] Univ York, Dept Biol, CNAP, York YO10 5YW, N Yorkshire - England

• Tipo de documento: Artigo Científico
• Fonte: BIOTECHNOLOGY FOR BIOFUELS; v. 6, MAY 9 2013.
• Citações Web of Science: 58

Resumo

Background: In recent years, the growing demand for biofuels has encouraged the search for different sources of underutilized lignocellulosic feedstocks that are available in sufficient abundance to be used for sustainable biofuel production. Much attention has been focused on biomass from grass. However, large amounts of timber residues such as eucalyptus bark are available and represent a potential source for conversion to bioethanol. In the present paper, we investigate the effects of a delignification process with increasing sodium hydroxide concentrations, preceded or not by diluted acid, on the bark of two eucalyptus clones: Eucalyptus grandis (EG) and the hybrid, E. grandis x urophylla (HGU). The enzymatic digestibility and total cellulose conversion were measured, along with the effect on the composition of the solid and the liquor fractions. Barks were also assessed using Fourier-transform infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance (NMR), X-Ray diffraction, and scanning electron microscopy (SEM). Results: Compositional analysis revealed an increase in the cellulose content, reaching around 81% and 76% of glucose for HGU and EG, respectively, using a two-step treatment with HCl 1%, followed by 4% NaOH. Lignin removal was 84% (HGU) and 79% (EG), while the hemicellulose removal was 95% and 97% for HGU and EG, respectively. However, when we applied a one-step treatment, with 4% NaOH, higher hydrolysis efficiencies were found after 48 h for both clones, reaching almost 100% for HGU and 80% for EG, in spite of the lower lignin and hemicellulose removal. Total cellulose conversion increased from 5% and 7% to around 65% for HGU and 59% for EG. NMR and FTIR provided important insight into the lignin and hemicellulose removal and SEM studies shed light on the cell-wall unstructuring after pretreatment and lignin migration and precipitation on the fibers surface, which explain the different hydrolysis rates found for the clones. Conclusion: Our results show that the single step alkaline pretreatment improves the enzymatic digestibility of Eucalyptus bark. Furthermore, the chemical and physical methods combined in this study provide a better comprehension of the pretreatment effects on cell-wall and the factors that influence enzymatic digestibility of this forest residue. (AU)

• Processo FAPESP: 10/11135-6 - Aspectos estruturais e morfológicos da degradação da parede celular e seus biopolímeros
• Beneficiário: Camila Alves de Rezende
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 08/56255-9 - Structure and function of enzymes and auxiliary proteins from Trichoderma, active in cell-wall hydrolysis
• Beneficiário: Igor Polikarpov
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOEN - Temático
• Processo FAPESP: 10/08370-3 - Estudos biofísicos e bioquímicos de exoglicanases do fungo Trichoderma harzianum envolvidas na biodegradação da celulose
• Beneficiário: Wanius José Garcia da Silva
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 10/52362-5 - Targeted analysis of microbial lignocellulolytic secretomes: a new approach to enzyme discovery
• Beneficiário: Igor Polikarpov
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 09/18354-8 - Dinâmica e estrutura de sistemas poliméricos estudados por ressonância magnética nuclear
• Beneficiário: Eduardo Ribeiro de Azevedo
• Modalidade de apoio: Auxílio à Pesquisa - Regular