Ultra-structural mapping of sugarcane bagasse after oxalic acid fiber expansion (OAFEX) and ethanol production by Candida shehatae and Saccharomyces cerevisiae

Autor(es)

Chandel, Anuj K. ^[1] ; Antunes, Felipe F. A. ^[1] ; Anjos, Virgilio ^[2] ; Bell, Maria J. V. ^[2] ; Rodrigues, Leonarde N. ^[2] ; Singh, Om V. ^[3] ; Rosa, Carlos A. ^[4] ; Pagnocca, Fernando C. ^[5] ; da Silva, Silvio S. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Engn Lorena, Dept Biotechnol, BR-12602810 Lorena, SP - Brazil

^[2] Univ Fed Juiz de Fora, Dept Phys, Mat Spect Lab, BR-36036330 Juiz De Fora, MG - Brazil

^[3] Univ Pittsburgh, Div Biol & Hlth Sci, Bradford, PA 16701 - USA

^[4] Univ Fed Minas Gerais, Dept Microbiol, Belo Horizonte, MG - Brazil

^[5] UNESP, CEIS, Inst Biosci, Dept Biochem & Microbiol, Rio Claro, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: BIOTECHNOLOGY FOR BIOFUELS; v. 6, JAN 16 2013.
• Citações Web of Science: 35

Resumo

Background: Diminishing supplies of fossil fuels and oil spills are rousing to explore the alternative sources of energy that can be produced from non-food/feed-based substrates. Due to its abundance, sugarcane bagasse (SB) could be a model substrate for the second-generation biofuel cellulosic ethanol. However, the efficient bioconversion of SB remains a challenge for the commercial production of cellulosic ethanol. We hypothesized that oxalic-acid-mediated thermochemical pretreatment (OAFEX) would overcome the native recalcitrance of SB by enhancing the cellulase amenability toward the embedded cellulosic microfibrils. Results: OAFEX treatment revealed the solubilization of hemicellulose releasing sugars (12.56 g/l xylose and 1.85 g/l glucose), leaving cellulignin in an accessible form for enzymatic hydrolysis. The highest hydrolytic efficiency (66.51%) of cellulignin was achieved by enzymatic hydrolysis (Celluclast 1.5 L and Novozym 188). The ultrastructure characterization of SB using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, Fourier transform-near infrared spectroscopy (FT-NIR), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) revealed structural differences before and after OAFEX treatment with enzymatic hydrolysis. Furthermore, fermentation mediated by C. shehatae UFMG HM52.2 and S. cerevisiae 174 showed fuel ethanol production from detoxified acid (3.2 g/l, yield 0.353 g/g; 0.52 g/l, yield, 0.246 g/g) and enzymatic hydrolysates (4.83 g/l, yield, 0.28 g/g; 6.6 g/l, yield 0.46 g/g). Conclusions: OAFEX treatment revealed marked hemicellulose degradation, improving the cellulases' ability to access the cellulignin and release fermentable sugars from the pretreated substrate. The ultrastructure of SB after OAFEX and enzymatic hydrolysis of cellulignin established thorough insights at the molecular level. (AU)

• Processo FAPESP: 10/11258-0 - Desenvolvimento de processos de sacarificação e co-fermentação simultânea usando cultura mista de leveduras para produção de etanol usando bagaço de cana pré-tratado por amônia
• Beneficiário: Anuj Kumar
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 08/57926-4 - Etanol: pesquisa e desenvolvimento visando ao aproveitamento integrado do bagaço de cana-de-açúcar para a produção biotecnológica do etanol lignocelulósico
• Beneficiário: Silvio Silvério da Silva
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOEN - Temático