Liquefaction of sugarcane bagasse for enzyme production

Bioprocessing of sugarcane bagasse to produce second generation (Gen 2) ethanol is carried out through a sequence of steps:  pretreatment, hydrolysis, and fermentation.  The localized nature of Brazilian ethanol facilities may benefit from on-site production of cellulase enzymes.  This has motivated research on cellulase production using a combination of solid state cultivation and submerged fermentation through Embrapa and UFSCar, at solids loadings of up to 30% w/volume, which may require significant power input in order to achieve adequate mixing during the aerated fermentations.  This work addresses enzyme induced liquefaction of sugarcane bagasse in a fed batch reactor based on addition of a cellulolytic strain of Aspergillus, discovered in the brazilian biome, that secretes cellulase, hemicellulases, and b-glucosidase when grown on sugarcane bagasse.  In this work Aspergillus niger A12 was initially incubated in solid-state cultivation 30% (w/w) for 72h at 32°C.  Suspensions of this material were mixed under fed-batch conditions with commercial available endoglucanase (301 IU per gram of dry solids) at 32°C and 50°C, pH 4.8, 290 rpm for 24 h and 48 h.  The solids fed-batch intervals were 0, 1, 2, 3, 6, 9 and 12h.  The material was liquefied after 48 hours, and the viscosity was slightly lower at 32°C than at 50°C (0.30 and 0.48 Pa.s, respectively, at 100 s^-1 shear rate).  Effects of liquefaction on enzyme production by the Aspergillus sp is discussed, and impacts on enzyme titers compared to solid state fermentations, presented.