Applications of Microbial β-Mannanases

Abstract

Mannans are main components of hemicellulosic fraction of softwoods and they are present widely in plant tissues. β-mannanases are the major mannan-degrading enzymes and are produced by different plants, animals, actinomycetes, fungi, and bacteria. These enzymes can function under conditions of wide range of pH and temperature. Applications of β-mannanases have therefore, been found in different industries such as animal feed, food, biorefinery, textile, detergent, and paper and pulp. This review summarizes the most recent studies reported on potential applications of β-mannanases and bioengineering of β-mannanases to modify and optimize their key catalytic properties to cater to growing demands of commercial sectors.

Keywords: bioengineering; hemicellulose; heterologous production; industrial applications; microbial β-mannanase.

FIGURE 1

Action of β-mannanase on different types of mannan. Modified from Yeoman et al. (2010).

FIGURE 2

Schematic representation of modular structure of β-mannanase, displaying the Tim barrel structure. Major α-helices are colored red while β-strands are shown as yellow, labeled in accordance with the ideal (β/α)8 barrel structure. Adopted with permission from Zhao et al. (2011).

FIGURE 3

Reaction mechanism of β-mannanase. Modified from Sharma et al. (2018). The brackets indicate transition state. P1 is product 1, P2 is product 2.

FIGURE 4

Overview of bioethanol production from lignocellulosic biomass based on β-mannanase hydrolysis.

FIGURE 5

Comparison of soluble coffee production by enzymatic and thermal hydrolysis. Modified from Baraldi et al. (2016).