Isolation and Identification of Esterase Producing Bacillus Subtilis from Soil
Keywords:Bacillus subtilis, industrial areas of Lahore, tributyrin substrate, zone formation test, esterase enzyme, soil.
Bacillus subtilis is most widely used bacteria for the production of different enzymes and chemicals. The aim of this study was to isolate the esterase enzyme producing bacterial strains from soil samples in Lahore, Pakistan. A total of thirty soil samples collected from different industrial areas were examined microscopically. Starch hydrolysis test was performed to confirm the gram positive bacteria Bacillus subtilis. Primary screening of esterase activity on agar plates was done with tributyrin substrate and clear zones or opaques around the colonies indicated this activity. The bacterial colonies range from 1 to 2mm in diameter. Bacterial colonies isolated from all samples were purple in color and gram positive while sample number 10 and 26 were slightly positive and appeared cocci in shape under microscope. The spores appeared green and oval in shape. These spores were observed in all samples but absent in sample 10 and 26. The colonies were creamy white, shiny white or dull yellow in color. Colonies were irregular, wrinkled, sticky, serrate, umbonate, opaque, circular, rounded flat in appearance. Positive zone formation in tributyrin substrate confirmed the production of esterase enzyme by Bacillus subtilis. Sample number 10, 16, 18 and 26 showed negative zone formation test. It might be because the soil samples were collected from the site where the chemicals from the industry are falling on the soil. The chemicals might have killed some of the microorganisms in the soil.