The production and activity of extracellular amylase by Rhizoctonia bataticola

Rhizoctonia bataticola produced the highest amounts of amylase in medium containing starch than that lacking starch within the 10 days of culture. Doubling the concentration of starch in the growth medium resulted in a near doubling of the amylase activity. Amylase production by the fungus is related to the type of carbon source in the medium with maximum amylase produced in medium containing starch. The maximum activity of the enzyme was detected in extracellular filtrates obtained from 4 days cultures. After this period, amylase activity decreased at first, and then increased through the 10 days incubation period. The fungus produced maximum levels of amylase prior to attainment of maximum mycelial biomass. Peak activity of the extracellular amylase was recorded at a temperature and pH range of 20–25°C and 4–5 respectively. The role of the exoenzyme in the deterioration of stored food products and its possible use in industrial fermentation processes are discussed.