Microbial Cellulases: A Review on Strain Development, Purification, Characterization and their Industrial Applications

Review Article

J Bacteriol Mycol. 2021; 8(5): 1180.

Microbial Cellulases: A Review on Strain Development, Purification, Characterization and their Industrial Applications

Sher H1,2, Zeb N1,3, Zeb S4, Ali A4, Aleem B1, Iftikhar F1, Rahman SU1 and Rashid MH1,2*

1National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan

2Pakistan Institute of Engineering and Applied Sciences (PIEAS), Islamabad, Pakistan

3Department of Biotechnology and Microbiology, Women University Mardan, KP, Pakistan

4Department of Microbiology, Abdul Wali Khan University Mardan, KP, Pakistan

#First two authors contributed equally

*Corresponding author: Muhammad Hamid Rashid, Industrial Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan

Received: May 17, 2021; Accepted: July 05, 2021; Published: July 12, 2021

Abstract

In this advance era, the enzymes are considered as a core kernel of white biotechnology and their demand is increasing day by day. According to report published in Research and Markets (ID: 5009185), the estimated global market for industrial enzymes were USD 10.0 billion in 2019, which is continuously increasing as it is expected to reach about USD 14.7 billion by 2022. Among all enzymes, cellulases are the major group of enzymes act synergistically in breakdown of cellulose, that facilitates its conversion to various value-added products and also offer several other important applications at industrial scale. The hyper production of cellulases are required to overcome their demand of global market. Cellulases production can be enhanced by strain improvement as well as using advance fermentation technology. In this review a detail studies of strategies to enhance production of cellulases and improve their physiochemical properties for industrial application have been described.

Keywords: Enzyme; Cellulase; Aspergillus; Immobilization; Fermentation; Strain improvement

Abbreviations

Mpa Pressure: Mega Pascal Pressure Unit; A. oryzae: Aspergillus oryzae; A. sojae: Aspergillus sojae; CaCl2: Calcium Chloride; NaCl: Sodium Chloride; UV: Ultraviolet Radiations; SmF: Submerged Fermentation; CMC: Carboxymethyl Cellulose

Introduction

Enzymes are the proteinaceous macromolecules and biological catalysts that are produced by all living organisms and involved in vital processes of life. They are also considered as the most promising alternative to chemical catalysts as they are highly specific and can carry out the catalysis at very minimum and milder reaction conditions [1- 3]. Enzymes are employed in various processes in industries as they are non-toxic, biodegradable and can produce higher concentration of better-quality products by utilizing small number of raw materials. Enzymes are sustainable at both in vivo and in vitro conditions [4]. Various living systems are used for the extraction of industrially important enzymes including; animals (Pepsin, Trypsin), plants (Papain, Bromelain) and microorganisms (a-amylase, Glucoamylase, Cellulase) while bulk amount of enzymes can be obtained from microorganisms [5]. The demand for enzymes is increasing day by day and according to report published in Research and Markets (ID: 5009185), the estimated global market for industrial enzymes were USD 10.0 billion in 2019, which is continuously increasing so it is expected to reach about USD 14.7 billion by 2022. In this advance era, the enzymes are considered as a core kernel of biotechnology as they are the main agent to run important industrial biotechnological processes. In order to meet the increasing demands, enzymes are produced from microorganisms because they are the primary source of enzymes, having short life span, easy to culture and also desired genetic variations to enhance production of enzymes can be carried out easily comparative to plants and animals.

The enzymes produced by microorganisms are comparatively more stable as they can work in various temperature and pH, therefore the microbial enzymes can be withstanding in industrial bioprocesses. The microorganisms can be also genetically modified or mutated to enhance the production of enzymes as well as to improve the enzymatic activity and stability [6]. The best renewable energy sources for microorganisms are lignocellulosic materials and this is also the major structural components of plants. It is composed of a complex mixture of carbohydrate polymers such as; cellulose, hemicellulose, lignin and some other components termed as extractives [7-9]. These all components of lignocellulosic biomass are interconnected with each other in different percentage and form a hetero-matrix. Mostly the composition of the main polymers of legionellosis biomass is; Cellulose (30-60 %), Hemi cellulosic (20-40 %), Lignin (10-25 %) [10]. The plant genetics, environmental factors and the sources of biomass greatly influence the composition of polymers in lignocellulose materials [11]. The cellulose of biomass or plant cellulosic parts can be converted into sugars for further processing by cellulases enzyme followed by pre-treatments.

In recent few decades, the soluble sugar and other products obtained from the conversion of cellulosic materials was further used as precursor for the production of fuels, ethanol or other important biochemical products [12]. For this purpose, enzymes are playing an important role in the hydrolysis of cellulosic biomass and conversion to valuable products. Among all enzymes, cellulases are the major enzyme involved in breakdown of cellulose. Therefore, the cellulases produced through advanced biotechnological processes is further used for the depolymerisation of cellulose and also offers several other important applications at industrial scale [13,14]. Though, few reviews are available on cellulase enzyme especially focusing on their biotechnological production and strategies to improve their productions and properties. However, in this review we have reported the methods of strain improvements for optimization of cellulases enzyme production through advanced fermentation technology and their industrials applications (Figure 1).