The hydrolysis of lignocellulosic biomass catalysed by cellulases is a crucial step of the biorefinery approach for the production of fuels and chemicals. It is a heterogeneous process involving cellulases as biocatalysts that can be inhibited by produced sugars (glucose and cellobiose). The heterogeneous process includes the enzyme interaction with biomass and the subsequent cellulose and hemicellulose enzymatic hydrolysis. In this study a kinetic characterization of the commercial cellulase cocktail Cellic CTec2 (Novozymes) was carried out. Industrial apple residues were pretreated with NaOH1 hydrolysis and lignin conversion by laccases2. After the pretreatment step the kinetic characterization of the enzymatic hydrolysis step was carried out in term of effect of mixing rate, substrate and enzyme concentrations. The experimental results were described through pseudo-homogeneous Michaelis-Menten, modified Michaelis-Menten and Chrastil's models3. Parameters of the Michaelis-Menten models describe the mutual affinity between the enzyme and the biomass, they were lower (Km=6g L-1, Ke=5 g L-1) for alkaline pretreated biomasses than for biomass pretreated with laccases (Km=9g L-1, Ke=7g L-1). The n parameter of the Chrastil's model shows the apparent order of reaction and n<0.6 shows apparent reaction rates limited by diffusion. It resulted 0.17 and 0.4 for alkaline and laccase pretreated biomass, respectively, thus it suggests a quite large effect of the unspecific alkaline pretreatment on biomass structure. Accordingly, a lower lignin content was obtained after NaOH pretreatment with respect to the lignin content obtained after laccases pretreatment. The reported results show how these kind of studies can provide useful information to optimize the enzymatic hydrolysis step depending on the biomass composition after the pretreatment step.
KINETICS OF ENZYMATIC HYDROLYSIS OF CELLULOSE: EFFECT OF BIOMASS COMPOSITION AND PRETREATMENT
A Procentese;I Di Somma;ME Russo
2017
Abstract
The hydrolysis of lignocellulosic biomass catalysed by cellulases is a crucial step of the biorefinery approach for the production of fuels and chemicals. It is a heterogeneous process involving cellulases as biocatalysts that can be inhibited by produced sugars (glucose and cellobiose). The heterogeneous process includes the enzyme interaction with biomass and the subsequent cellulose and hemicellulose enzymatic hydrolysis. In this study a kinetic characterization of the commercial cellulase cocktail Cellic CTec2 (Novozymes) was carried out. Industrial apple residues were pretreated with NaOH1 hydrolysis and lignin conversion by laccases2. After the pretreatment step the kinetic characterization of the enzymatic hydrolysis step was carried out in term of effect of mixing rate, substrate and enzyme concentrations. The experimental results were described through pseudo-homogeneous Michaelis-Menten, modified Michaelis-Menten and Chrastil's models3. Parameters of the Michaelis-Menten models describe the mutual affinity between the enzyme and the biomass, they were lower (Km=6g L-1, Ke=5 g L-1) for alkaline pretreated biomasses than for biomass pretreated with laccases (Km=9g L-1, Ke=7g L-1). The n parameter of the Chrastil's model shows the apparent order of reaction and n<0.6 shows apparent reaction rates limited by diffusion. It resulted 0.17 and 0.4 for alkaline and laccase pretreated biomass, respectively, thus it suggests a quite large effect of the unspecific alkaline pretreatment on biomass structure. Accordingly, a lower lignin content was obtained after NaOH pretreatment with respect to the lignin content obtained after laccases pretreatment. The reported results show how these kind of studies can provide useful information to optimize the enzymatic hydrolysis step depending on the biomass composition after the pretreatment step.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
