Biotechnology of Microbial Xylanase: Overview

Biotechnology of Microbial Xylanase: Overview

Hooi Ling Ho (UCSI University, Malaysia)
DOI: 10.4018/978-1-5225-5237-6.ch013

Abstract

Xylanases are inducible enzymes responsible for the complete hydrolysis of xylan into xylose. Both solid state fermentation (SsF) and submerged fermentation (SmF) are used in the production of xylanase. SsF has become a popular approach due to its economic value. In fact, higher biomass and lower protein breakdown are among the factors involved in determining the production of xylanases in SsF. Agricultural extracts which are abundantly available in the environment such as rice bran and wheat bran are commonly used as the potential carbon source in xylanases production. Xylanase is indeed one of the valuable enzymes which show immense potential in vast industrial applications. The demand for xylanase is increasing because of its prodigious utilization in pulp and paper, bakery, food and beverage, detergents, textile, and animal feed. Xylanase has therefore become one of the important commercial enzymes in recent years.
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Introduction

Xylanases are inducible enzymes which responsible for the complete hydrolysis of xylan into simpler compounds, mainly xylose (Gupta & Kar, 2009). Xylanases are genetically single chain glycoproteins with molecular weight of 6 kDa to 80 kDa. Xylanases are active between pH 4.5 to 6.5 from 40°C to 60°C. Xylanases are produced by numerous numbers of different fungi.Various strains of filamentous fungi such as Aspergillus niger, Aspergillus oryzae and Trichoderma spphave been reported to be the potent producers of xylanases. However, xylanases production is typically restricted to Aspergillus spp and Trichoderma spp in the industrial scale (Dietmar, Bernd, Kulbe, Walter, & Silvia, 1996). Meanwhile, Aspergillus spp are normally selected and optimised for xylanases production. Apart from xylanases, Aspergillus spp also produce huge variety of extracellular enzymes including amylase, cellulase and protease (Pandey, Nigam, Soccol, Soccol, Singh, & Mohan, 2000). Xylanase shows tremendous potential in many industrial processes especially in textiles, leather, detergents and baking (Bhatnagar, & Imelda-Joseph, 2010). Both solid state fermentation (SsF) and submerged fermentation (SmF) are used in the production of fungal xylanase. SsF has become a popular approach to produce xylanase due to its economical value that does not involved complicated technology. Viniegra-Gonzalez et al. (2003) studied the comparison between SsF and SmF in terms of enzymes production. In fact, they identified out that higher biomass and lower protein breakdown were among the factors involved in determining the production of enzymes in SsF. Besides that, the utilization of inexpensive agricultural extracts in SsF is environmentally sound because besides providing sufficient nutrients as carbon source, it reduces pollutions to the surroundings. Hence, SsF is more economical compared to SmF. Indeed, SsF is in fact, an attractive and economical method for xylanases production especially for fungal cultivations. SsF produces higher enzymes productivity using lower operation and capital cost (Lonsane, Ghildyal, Budiatman, & Ramakrishna, 1985). Malaysia with abundant natural rainforest will be of great advantage in xylanase production using SmF and SsF. Natural resources and agricultural extracts which are abundantly available in the environment such as rice bran, wheat bran, palm kernel cake and soybean hulls are used as potential carbon sources in xylanases production under SmF and SsF (Pang & Ibrahim 2005).

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