Chiang Mai Journal of Science

Amylase enzymes are currently used to accelerate starch degradation in many industrial processes. Streptomyces sp., an endophytic actinomycete, is well known as a potential source of hydrolytic enzymes, antimicrobial agents, and many secondary metabolites. Previously, an endophytic Streptomyces griseoflavus P4 was isolated from sweet pea root and identified by 16S rRNA sequence analysis. Using a plate assay, the S. griseoflavus P4 was found to be capable of producing amylase enzymes, as a clear zone around colonies appeared after iodine reagent was added to the plate. The maximum amylase activity was 1.66±0.07 U/mL on the 7^th day of growth, while the total biomass was 0.085±0.005 g of dry pellet in 100 mL medium. In this work, the P4 strain exhibited a specific activity of 118.4 U/mg protein. Amylase production was found to be growth-associated and started in a log phase.  Maximum enzyme production was reached during the stationary phase. The optimal conditions for activity were found to be 40 degrees C and a pH of 7.