Abstract

The objective of the present study was to isolate, identify and optimize potential amylase producing bacteria and actinomycetes from soil samples. The soil samples were collected from Maraki and Tewedros campus, University of Gondar. Isolation was done by serial dilution and spread plate method. Primary screening of amylolytic activity of the isolates was performed by starch agar plate method. The submerged state fermentation method followed for the production of amylase by the optimization of temperature, pH, fermentation time and substrate concentration. From the soil samples, 18 isolates were identified and subjected to primary screening for amylolytic activity. Of which, five isolates were observed with maximum amylolytic activity during the primary screening. During the submerged state fermentation, maximum amylase activity was observed at 48 h and then declined. The optimum temperature observed for maximum amylase activity of Bacillus was 40°C and Streptomyces at 37°C. The highest amylase activity was observed at neutral pH and 4% of starch concentration. The colony morphology, Gram reaction, biochemical tests and Bergey’s manual of determinative bacteriology confirm the promising isolates belong to the genus Bacillus and Streptomyces. This preliminary study could provide base line information for the discovery of novel microbes from the natural resources for the production of amylase which will be used for multipurpose.

Key words: Amylase, isolation, optimization, submerged state fermentation.