ABSTRACT

Yam is in the class of roots and tubers that is a staple of the Nigerian and West African diet but fungi organisms can degrade it causing yam rot by producing amylolytic and beta-glucanase enzymes which breakdown starch and cellulose, respectively into sugars. They were produced using yam rot fungi isolated on SDA medium. The isolates obtained were all Aspergillus sp, they were identified using their morphological characteristics, lactophenol cotton blue stain and slide culture test. Pathogenicity test was carried out to check if the isolates could cause rot. Agar plate screening was carried out to check for the enzyme activites of the isolates, this was done on starch agar and carboxymethyl cellulose agar. It was detected by the disappearance of the blue colour and red colour, respectively around the colony producing a clear zone. The Aspergillus isolates were used to produce amylase and β-glucanase enzyme in spectrophotometric enzyme assay in which the enzyme activity was determined at OD540nm. Amylase and beta-glucanase production was carried out using the 4 isolates in solid state fermentation. The amount of beta-glucanase produced was 0.0097U/ml for Aspergillus spC followed by Aspergillus spD which gave 0.0020U/ml, Aspergillus spA gave 0.0015U/ml and Aspergillus spB being the least producer measuring 0.0005U/ml. All isolates showed good results for the production of amylase, in other words, they are all good producers of amylase with Aspergillus spB being the least producer with 0.0335U/ml, Aspergillus spA is the best producer with 0.0800U/ml, followed by Aspergillus spC (0.0601U/ml) and Aspergillus spD (0.0500U/ml).