ABSTRACT

Yam is one of the most important food in the world, Yam is one of the major sources of carbohydrate, minerals, vitamins B6 and C, dietary fibre. Fungi organisms have the ability to degrade yam by producing amylolytic and beta-glucanase enzymes which breakdown starch and cellulose, hence causing yam rot. Spread pate technique was adopted in isolation of phytopathogenic fungi from spoilt yarn, members of the genera; Aspergillus, Rhizopus and Botryodiplodia were isolated and identified using their morphological and microscopic characteristics. Pathogenicity test confirmed the isolates could cause rot. Preliminary screening using agar plate method was carried out for production of amylase and beta-glucanase by the isolate. The amylase and beta-glucanase enzyme activities was determined in spectrophotometric enzyme assay at 0D540 nm. The beta-glucanase produced was highest in Aspergillus sp (1.556 U/mi) followed by Rhizopus stolonjfer (0.930 U/mi), Aspergillus nidulans (0.905 U/mi), Botryodiplodia sp (0.706 U/mI) and the least was obtained from Botryodiplodia theobromae (0.617 U/mi) Also the amylase activities are as follows; Aspergillus sp was the best producer with (1.614 U/mi), foliowed by Rhizopus stolonifer (0.986 U/mi), Aspergillus nidulans (0.961 U/mi), Botryodiplodia sp (0.672 U/mi) and Botryodiplodia theobomae being the least producer with (0.672 U/mi), All isolates were amylase and beta-glucanase producer hence their ability to spoil yam. Botryodiplodia theobromae was more prevalent than other phytopathogenic fungi isolated because it is the most common phytopathogen found in yam.