Latest Research News on Cellulase : Dec 2021

Methods for measuring cellulase activities

The physical heterogeneity of the substrate and the complexity of the cellulase enzyme system present those wishing to measure cellulase activities with formidable problems. Faced with the use of substrates that are ill defined, and an enzyme system that consists often of a multitude of enzymes acting in synergism in a manner not yet fully understood, the enzymologist has developed a bewildering number of assays in an attempt to throw some light on the complex enzymatic interactions involved in the breakdown of cellulose. This state of affairs, compounded by the existence of a plethora of arbitrary units of activity, has made comparison of quantitative data obtained in various laboratories impossible. This chapter describes a number of alternative assay methods that may help toward a better evaluation of cellulase components and their complex interactions that result in the solubilization of cellulose. Some of these alternative methods are included for practical considerations and many are included because of the nature of the unresolved problems.[1]


Measurement of saccharifying cellulose

A filter paper assay method and unit value is described for the measurement of enzyme saccharification action. The method is simple, reproducible, and quantitative and predicts enzyme action under practical saccharification conditions.[2]


Outlook for cellulase improvement: Screening and selection strategies

Cellulose is the most abundant renewable natural biological resource, and the production of biobased products and bioenergy from less costly renewable lignocellulosic materials is important for the sustainable development of human beings. A reduction in cellulase production cost, an improvement in cellulase performance, and an increase in sugar yields are all vital to reduce the processing costs of biorefineries. Improvements in specific cellulase activities for non-complexed cellulase mixtures can be implemented through cellulase engineering based on rational design or directed evolution for each cellulase component enzyme, as well as on the reconstitution of cellulase components. Here, we review quantitative cellulase activity assays using soluble and insoluble substrates, and focus on their advantages and limitations. Because there are no clear relationships between cellulase activities on soluble substrates and those on insoluble substrates, soluble substrates should not be used to screen or select improved cellulases for processing relevant solid substrates, such as plant cell walls. Cellulase improvement strategies based on directed evolution using screening on soluble substrates have been only moderately successful, and have primarily targeted improvement in thermal tolerance. Heterogeneity of insoluble cellulose, unclear dynamic interactions between insoluble substrate and cellulase components, and the complex competitive and/or synergic relationship among cellulase components limit rational design and/or strategies, depending on activity screening approaches. Herein, we hypothesize that continuous culture using insoluble cellulosic substrates could be a powerful selection tool for enriching beneficial cellulase mutants from the large library displayed on the cell surface.[3]


Cellulase Production by Bacteria: A Review

Cellulose is an abundant natural biopolymer on earth and most dominating Agricultural waste. This cellulosic biomass is a renewable and abundant resource with great potential for bioconversion to value-added bioproducts. It can be degraded by cellulase produced by cellulolytic bacteria. This enzyme has various industrial applications and now considered as major group of industrial enzyme. The review discusses application of cellulase, classification of cellulase, quantification of cellulase, the types of cellulolytic bacteria and their screening. It describes the current knowledge of cellulase production by submerged fermentation and solid state fermentation, properties of cellulase and cloning and expression of cellulase gene. The biotechnological aspect of cellulase research and their future prospects are also discussed.[4]


Cellulase Producing Potential of Aspergillus terreus Uv2 on Cellulosic Wastes Pretreated with Acid and Alkali

Aims: Cellulases offer very wide applications in biotechnology and enzymes from microbial origins present inexpensive source. Production of value added chemicals from wastes will be an exciting translation from waste to wealth and an eco-friendly initiative instead of the incineration option often given to cellulosic wastes.

Study Design: Sulphuric acid and Sodium hydroxide solutions were prepared at 0.5 M and 2 M concentrations to pretreat three cellulosic wastes that had been made neutral prior to fermentation with a known cellulase producing mold

Place and Duration of Study: All experiments were conducted in the laboratory of the Department of Microbiology, Federal University of Technology, Minna, Nigeria for a period of six weeks.

Methodology: Hypercellulase producing Aspergillus terreus UV2 strain was used to ferment pretreated cellulosic wastes: Corn cob, corn straw and bagasse, using submerged fermentation in Mandel basal medium. The crystalline lignocelluloses were milled and fractionated into 850 μ particle size and pretreated in two concentrations (0.5 M and 2 M) of both acid (sulphuric acid) and alkali (sodium hydroxide) independently and were left for varying residence time of one hour or three hours in the digester at ambient temperature, Optimum spore concentration of 1.0 x 106 spores/ml and pH of 4.8. Supernatants of crude enzyme were taken and assayed at 24 hours interval.

Results: Cellulase activity peaked at 96 hours. Enzyme secretion in the cellulosic wastes was highest in sugarcane bagasse, followed by the corn cob and then the corn straw corresponding to 51%, 40% and 16% respectively. Alkali pretreated cellulosics gave higher yield of cellulase than its counterpart acid. Non-pretreated residues gave only low enzyme titers. Bagasse produced optimum cellulase yield of 0.068 IU/ml/min within 120 hours when subjected to 2 M NaOH digestion for one hour before fermentation. This translated to 39% increase in enzyme expression when compared with non-treated bagasse of 0.049 IU/ml/min. Conclusion: Sugarcane bagasse therefore when digested with mild alkali (2 M NaOH) for a pretreatment period of one hour holds a great possibility for cellulase production using a mutant mold, Aspergillus terreus UV2. Production of value added chemicals from cellulosic wastes will be an exciting translation from waste to wealth.[5]

Reference

[1] Wood, T.M. and Bhat, K.M., 1988. Methods for measuring cellulase activities. Methods in enzymology, 160, pp.87-112.

[2] Mandels, M., Andreotti, R. and Roche, C., 1976, January. Measurement of saccharifying cellulase. In Biotechnol. Bioeng. Symp.;(United States) (Vol. 6). Army Natick Development Center, MA.

[3] Zhang, Y.H.P., Himmel, M.E. and Mielenz, J.R., 2006. Outlook for cellulase improvement: screening and selection strategies. Biotechnology advances, 24(5), pp.452-481.

[4] Sadhu, S. and Maiti, T.K., 2013. Cellulase production by bacteria: a review. Microbiology Research Journal International, pp.235-258.

[5] Damisa, D., Kuta, F.A., Abioye, O.P., Bala, J.D. and Egbe, N.E., 2015. Cellulase Producing Potential of Aspergillus terreus Uv2 on Cellulosic Wastes Pretreated with Acid and Alkali. Biotechnology Journal International, pp.1-10.

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