title: Use of spectroscopic and imaging techniques to evaluate pretreated sugarcane bagasse as a substrate for cellulase production under solid-state fermentation.
abstract: The enzymatic cocktail of cellulases is one of the most costly inputs affecting the economic viability of the biochemical route for biomass conversion into biofuels and other chemicals. Here, the influence of liquid hot water, dilute acid, alkali, and combined acid/alkali pretreatments on sugarcane bagasse (SCB) used for cellulase production was investigated by means of spectroscopic and imaging techniques. Chemical composition and structural characteristics, such as crystallinity (determined by X-ray diffraction), functional groups (Fourier transform infrared spectroscopy), and microstructure (scanning electron microscopy), were used to correlate SCB pretreatments with enzymatic biosynthesis by a strain of the filamentous fungus Aspergillus niger under solid-state fermentation. The combined acid/alkali pretreatment resulted in a SCB with higher cellulose content (86.7%). However, the high crystallinity (74%) of the resulting biomass was detrimental to microbial uptake and enzyme production. SCB pretreated with liquid hot water yielded the highest filter paper cellulase (FPase), carboxymethyl cellulase (CMCase), and xylanase activities (0.4, 14.9, and 26.1 U g(-1), respectively). The results showed that a suitable pretreatment for SCB to be used as a substrate for cellulase production should avoid severe conditions in order to preserve amorphous cellulose and to enhance the physical properties that assist microbial access.
authors.affiliation: Embrapa Instrumentation, Rua XV de Novembro, 1452, 13560-970, São Carlos, São Paulo, Brazil, ursularz@gmail.com.
authors.forename: Ursula Fabiola
authors.initials: UF
authors.lastname: Rodríguez-Zúñiga
authors.forename: Victor
authors.initials: V
authors.lastname: Bertucci Neto
authors.forename: Sonia
authors.initials: S
authors.lastname: Couri
authors.forename: Silvio
authors.initials: S
authors.lastname: Crestana
authors.forename: Cristiane Sanchez
authors.initials: CS
authors.lastname: Farinas
mesh_terms: D001234:Aspergillus niger / Q000378:metabolism*; D056804:Biofuels; D002480:Cellulase / Q000096:biosynthesis*; D002482:Cellulose / Q000378:metabolism* / Q000648:ultrastructure; D003460:Crystallization; D043364:Endo-1,4-beta Xylanases / Q000096:biosynthesis*; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D006358:Hot Temperature; D006868:Hydrolysis; D008855:Microscopy, Electron, Scanning; D031786:Saccharum / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013464:Sulfuric Acids / Q000737:chemistry; D014867:Water; D014961:X-Ray Diffraction
chemical_list: D056804:Biofuels; D013464:Sulfuric Acids; D014867:Water; D000431:Ethanol; D012972:Sodium Hydroxide; D002482:Cellulose; C027433:bagasse; D002480:Cellulase; C019826:carboxymethylcellulase; D043364:Endo-1,4-beta Xylanases; C033158:sulfuric acid