Enzymatic Hydrolysis of Pretreated Kenaf using a Recombinant Xylanase: Effects of Reaction Conditions for Optimum Hemicellulose Hydrolysis

Abstract

An efficient hemicellulose hydrolysis has now become a crucial step for xylooligosaccharides production for food additives and nutraceuticals industries. In this study, xylanase hydrolysis of pretreated hemicellulosic kenaf (Hibiscus cannabinus) for substantial hemicellulose hydrolysis was demonstrated. Experiments were performed primarily to investigate the effect of several critical reaction conditions towards the enzymatic hydrolysis of the pre-treated kenaf. The effects of various ranges of reaction conditions (substrate loading, xylanase loading, pH, temperature and time) were systematically and thoroughly studied. The study of hemicellulosic kenaf conversion using single enzyme was proven to effectively yield up to 59% of conversion after 48 h incubation using 3% (w/v) of substrate loading and 400 U of xylanase loading at 50°C in pH 4.0 buffer systems. The use of a single xylanase on the pre-treated kenaf was a key parameter in understanding the action of the main hemicellulose degrading enzyme towards hydrolysing the hemicellulose backbone of the pre-treated kenaf. Enzyme feeding strategy was also conducted and the results revealed that a batch feeding strategy of 400 U xylanase loading yielded the highest hemicellulose hydrolysis compared to the other fed batch enzyme feeding strategy. It was concluded that each reaction conditions and enzyme feeding strategy gave a significant impact towards the enzymatic hydrolysis and the use of optimum reaction conditions resulted in a high product yield at the end of the reaction. With the discovery of the importance of each reaction conditions involved in a hydrolysis, this study highlights the need for a comprehensive investigation on the reaction conditions using a mixture of enzymes towards achieving a complete hydrolysis with a higher product yield.

Xylose Release from Sunflower Stalk by Coupling Autohydrolysis and Enzymatic Post-Hydrolysis

“…Since xylan forms a complex with lignin that makes lignocellulosic biomass resistant to acid or enzymatic hydrolysis, xylose production carries out with two steps: pretreatment of lignocellulosic biomass and hydrolysis either acid or enzyme of it [12,13]. For the enzymatic hydrolysis of hemicellulose, lignocellulosic biomass can be treated with a chemical, mechanical, hydrothermal and/or a combination of these methods [5,7,9,14,15].…”

Production of Xylitol from Agricultural Waste by Enzymatic Methods

“…Less research has been conducted on the enzymatic synthesis of xylitol. Enzymatic saccharification of lignocellulose for the production of bioethanol (Madadi et al, 2017), for use in the pulp and paper industry (Walia et al, 2017) or for production of xylooligosaccharids (Akpinar et al, 2009;Yoon et al, 2006;Driss et al, 2014;Wan Azelee and Jahim, 2016) has been investigated. The enzymatic hydrolysis of xylan can be done with an endo-1-4-beta-xylanase (EC 3.2.1.8) and a beta-xylosidase (EC 3.2.1.3).…”

“…The enzymatic method of hemicellulose saccharification is specific for xylose and done under mild pH and temperature conditions that generally does not result in the production of microbial inhibitors, but has been shown to be not as efficient as acid digestion (Liavoga et al, 2007). Generally, the agricultural biomass will need a pre-treatment such as high temperature and pressure or the use of an alkali extraction to render the hemicellulose fraction more accessible to enzymatic attack (Liavoga et al, 2007;Yoon et al, 2006;Driss et al, 2014;Wan Azelee and Jahim, 2016;Akpinar et al, 2009).…”