Liquid Hot Water and Steam Explosion Pretreatment of Sugarcane Bagasse for Enzyme Production by a Sequential Solid-state and Submerged Method

RESUMO – The use of sugarcane bagasse on enzyme production is a promising alternative for reducing the costs of second generation ethanol. However, a pretreatment step is required to increase cellulose and hemicellulose accessibility. Here, the influence of Liquid Hot Water (LHW) and steam explosion (SE) pretreatments in cultivations with three Aspergillus strains were investigated. A new sequential method was carried out with a first step in solid-state for 24h, followed by the transition to submerged cultivation and enzyme production in the presence of 1% (w/v) of sugarcane for 72h. For both A. niger strains, the endoglucanase production was 20 to 50% higher in cultivations with steam exploded sugarcane bagasse. The xylanase and β-glucosidase production, however, were higher in LHW pretreated sugarcane bagasse, with xylanase production around 23% higher and β-glucosidase up to 4-fold higher. The A. niger A12 strain produced the higher titers of all enzymes evaluated, resulting in 1.26; 26.25; 3.70 and 0.58 IU.mL of endoglucanase, xylanase, β-glucosidase and βxylosidase, respectively, in LHW bagasse. Pretreated bagasse is not suitable for enzyme production by A. oryzae P27C3, indicating that this strain may be more sensitive to possible inhibitory products released from both pretreatments.