International Journal of Applied Agricultural Sciences 2019; 5(4): 82-89 http://www.sciencepublishinggroup.com/j/ijaas doi: 10.11648/j.ijaas.20190504.11 ISSN: 2469-7877 (Print); ISSN: 2469-7885 (Online) Purification and Characterization of Cellulase from Aspergillus niger Causing Soft Rot of White Yam in Three Environments in Nigeria Ajibade Gabriel Adegboyega, Abdulsalami Mohammed Sani, Denwe Samuel Dangwel, Oladapo Elizabeth Omolola * , Popoola Omokunmi Department of Biological Sciences, Faculty of Sciences, Nigeria Defence Academy, Kaduna, Nigeria Email address: * Corresponding author To cite this article: Ajibade Gabriel Adegboyega, Abdulsalami Mohammed Sani, Denwe Samuel Dangwel, Oladapo Elizabeth Omolola, Popoola Omokunmi. Purification and Characterization of Cellulase from Aspergillus niger Causing Soft Rot of White Yam in Three Environments in Nigeria. International Journal of Applied Agricultural Sciences. Vol. 5, No. 4, 2019, pp. 82-89. doi: 10.11648/j.ijaas.20190504.11 Received: May 4, 2019; Accepted: June 26, 2019; Published: July 30, 2019 Abstract: Aspergillus niger is abundant in most tropical soils and invariably, on the surface of yam tubers while still attached to the plant and on the root hairs during harvesting or storage. Naturally, the peridermic surface of the tubers function to exclude pathogen but damage caused by accidental incision or cut surface during weeding, insect attack and harvesting provide avenue for the infection. Aspergillus niger isolated from diseased yam in three zones in Nigeria synthesized cellulase which caused soft rot of the yam within nine days of inoculation. Microscopic and molecular analyses revealed two isolates of A. niger, P 1 and P 2, from different environment produced cellulase enzymes in significantly different proportions. When protein extracts from the infection were subjected to molecular exclusion chromatography, three peaks of absorption (A, B and C) were produced with only the components of peak A showing cellulase activity. Further fractionation of the components of peak A produced two absorption peaks (Aa and Ab) with only component Aa showing Cellulase activity. A. niger isolates, P 1 and P 2 showed considerable differences in the intensity of cellulase production suggesting that multiple strains of A. niger in the soil of yam-growing environments synthesized cellulase as transcriptional products in different manner underscoring the effect of physico – chemical properties of the soil on infectivity and virulence of the organism during yam rot. Keywords: Aspergillus niger, Cellulase, Soft Rot 1. Introduction The black mould rot of yam is caused by Aspergillus niger. The infection is characterized by decay of entire tuber during which the cells collapse with loss of integrity as a functional unit. In host-pathogen interaction, the ability of the pathogen to produce extracellular enzymes capable of degrading the host tissues is one of the more obvious properties influencing virulence [1]. A. niger is abundant in most tropical soils and, invariably, on the surface of yam tubers while still attached to the plant and on the root hairs during harvesting or storage. Naturally, the peridermic surface of the tubers function to exclude pathogen but damage caused by accidental incision or cut surface during weeding, insect attack and harvesting provide avenue for the infection. According to the study [2], chemotaxonomic characteristic is a virulence factor with variation arising from a multiplicity of factors including the nature of soil ecology and production of primary and secondary metabolites such as enzymes, aflatoxins and phytoalexins [1]. A. niger is able to synthesize cellulase enzyme complex that breaks down cellulose of the cell wall components into glucose [2] giving the organism access to utilize the tissues for its metabolism. According to these studies [1, 10], Cellulase {EC 3.2.1.4} secreted by pathogens play a critical role in softening and disintegrating the cell wall material. Cellulase facilitates the penetration and spread of the pathogen in the host and causes the collapse and