Fungal plant pathogens are known to produce extracellular enzymes that cleave virtually every glycosidic linkage in plant cell-wall polysaccharides'. The carbohydrate in the environment of the pathogen regulates the growth of microorganisms and the enzymes produced 2*3 The growth of fungus in submerged culture . solution is often accompanied by pH changes with time4*5; the changes are dependent on sources of carbon if the initial culture pH is kept con&u&.
Alternaria (SAl222), Colletrotrichum (Coil), Drechsiera (SAl208). and Fusarium moniiiforme (SAll90) are fungal pathogens that attack agricultural crops, which are either staple crops or crops of economic importance. These crops, e.g., rice (Oryzo sativa) and sorghum (Sorghum &color), are grown throughout West Africa. Sorghum and millet (Pennisetum typhoides), grown throughout the arid Savannah zones of West Africa, produce a low yield of amylase when malted, and consequently a low yield of fermentable sugars. It is necessary, therefore, to produce amylases and hemicellulases from microorganisms for the purpose of hydrolyzing hemicellulose and starch. Poor growth was observed for all the fungal samples cultured on agar plates. irrespective of the sources of carbon. After 24 h, all the fungal pathogens grew profusely on hemicellulose B, starch, or sucrose as source of carbon, except SA 1222. which grew poorly on hemicellulose B, but profusely on sucrose or starch. The maxrmum growth was observed between 120 and 144 h. Growth response of fungal pathogens with source of carbon has earlier been reported2*3.
Maximum enzyme activity (Tables I andII) was observed after 96 h for all the fungal pathogens, irrespective of the source of carbon used in the culture media; similar results were obtained previously by Dekker and Richards6, and Shambe'. The growth of SA 1222 and SA 1208 was observed throughout the solution, rather than only at the surface in the upper layer of the solution. In the case of Co11 and SA 1190, the growth was only at the surface in the upper layer, which suggests a requirement for aeration. Degradation by SA 1190, in culture solution, of its carbon ooos_6215/82/oooo4mo JSo2.75, @ 1982 -Elsevier scientiik Publishing Company