A discretized model for enzymatic hydrolysis of cellulose in a fed-batch process

Abstract

In the enzymatic hydrolysis of cellulose, several phenomena have been proposed to cause a decrease in the reaction rate with increasing conversion. The importance of each phenomenon is difficult to distinguish from batch hydrolysis data. Thus, kinetic models for the enzymatic hydrolysis of cellulose often suffer from poor parameter identifiability. This work presents a model that is applicable to fed-batch hydrolysis by discretizing the substrate based on the feeding time. Different scenarios are tested to explain the observed decrease in reaction rate with increasing conversion, and comprehensive assessment of the parameter sensitivities is carried out. The proposed model performed well in the broad range of experimental conditions used in this study and when compared to literature data. Furthermore, the use of data from fed-batch experiments and discretization of the model substrate to populations was found to be very informative when assessing the importance of the rate-decreasing phenomena in the model.

Synergism of cellulases and amylolytic enzymes in the hydrolysis of microalgal carbohydrates

“…13 Previous studies have examined the enzymatic hydrolysis of starch material using α-amylase and amyloglucosidase, [14][15][16][17][18] but the comparison between addition of these enzymes separately or in combination as hydrolyzing agents for algal starch has not been studied yet. The enzymatic hydrolysis of cellulosic material has been extensively investigated, [19][20][21][22][23] but there has been no attempt to describe the role of β-glucosidase in the hydrolysis of algal cellulose to glucose. Moreover, only a few studies have used mixed microalgae for biofuel production.…”

Hydrolysis and fermentation steps of a pretreated sawmill mixed feedstock for bioethanol production in a wood biorefinery

“…The simplest approach considers conventional or modified Michaelian kinetics with competitive, noncompetitive or uncompetitive inhibition, whereas the most complex modeling strategy may take cellulose polymerization degree or particle size and morphology through a population balance into account (Zhang et al, 2014;Lebaz et al, 2015). Alternative mechanistic models sometimes account for chemical or physical phenomena which may affect the kinetics of enzymatic hydrolysis of cellulose, such as concurrent reactions (Tsai et al, 2014), adsorption equilibria without or with inactivation of adsorbed cellulase (Kadam et al, 2004;Wang and Feng, 2010;Tervasmäki et al, 2017), fractal kinetics for heterogeneous reactions (Ye and Berson, 2011), or mixing conditions through mass transfer rate (Kinnarinen et al, 2012;Wojtusik et al, 2016). It must be pointed out that the complete mechanism of enzymatic hydrolysis is still unknown, and could also depend on the type and purity of the substrate and of the enzymes.…”

Direct Transformation of Cellulose to Gluconic Acid in a Concentrated Iron(III) Chloride Solution under Mild Conditions

“…Compared with existing methods, the current method is potentially competitive in cost, reaction time, and product yield for the production of gluconic acid directly from cellulose. For example, the fermentation process using fungi or bacteria had a high yield and a high selectivity, − but the process could use only glucose as a substrate. Cellulose must be hydrolyzed to glucose using cellulase or acid catalysts before it can be fermented to gluconic acid.…”