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Obtaining the kinetic parameters of the enzymatic hydrolysis of sugarcane bagasse using a new enzyme mixture from commercial Aspergillus Niger and a local strain of Bacillus subtilis (Bal3)

Abstract:

Sugarcane bagasse (SB) is a renewable, cheap, and readily available residue in most tropical countries. Its enzymatic hydrolysis can give some added value to this material, such as bio-ethanol production. However, one of the biggest challenges for its large scale implementation is its low cost-effectiveness. Reducing the volume of commercial enzymes utilized is a good strategy towards improving said cost-effectiveness. In this work, the use of a novel enzymatic cocktail composed of cellulases from the microorganisms Bacillus subtilis (Bal3) collected in Ecuador and commercially available Aspergillus niger has been studied to determine its kinetics parameters in the enzymatic degradation of SB. By using relatively mild conditions (50° C, 25 U/g enzymatic load, 200 rpm agitation speed, 15 h of reaction, 5% w/v solid percentage and 0.2% surfactant concentration of Tween 80), a total of 50.9 g of total reducing sugars (TRS) per 100 grams of pre-treated SB was obtained after 15 hours, and an expected maximum of 52.6 g of TRS at 24 hours was considered possible. A relatively low Michaelis-Menten apparent constant (KM) (9.10 g L1), the moderate reaction rate (Vmax) (0.54 g L1min1), negative inhibition apparent constant (K) (-15.7 h L1) of the enzymatic process and a high TRS yield made this method interesting for implementation into SB degradation for bioethanol production.