Isolasi Bakteri Dari Tanah Gunung Kapur Dan Pengujian Aktivitas Antibakteriisoiat Terhadap Bakteri Escherichia Coli Dan Staphylococcus Aureus

Antibiotics arc metabolites produced by microorganisms, which can kill or inhibit the growth of other microorganisms. Some bacteria have developed resistances against the antibiotics so that the common antibiotics lose its therapeutic values. Various antibiotic-producing microorganisms have been isolated in order to find new types of antibiotics from various sources, commonly from forest soils. In this research, the antibiotic producing microorganisms had been isolated from soil of limestone mountain at Gunung Kapur, IT Semen Gresik. The antibacterial activity of each isolates was assayed against the Staphylococcus aureus and Escherichia coli by applying thesupcrnatant5 into the cylinder cups. The diameters of inhibition areas around the cups were measured. Five isolates were obtained from the isolation steps. All of them had similar colonies morphologies which were white-circular colonies with entire marginduring l-2 day incubation and then became serrated. Among all of the isolates, thelsolate 1 showed the largest antibacterial activity with a diameter of l.59±0.036cm against Staphylococcus aureus 1.22±0.017cmagainst Escherichia coli. The characterization results showed that Isolated I wasa Gram positive and rod-shaped bacterium with a centered-spore;catalase negative, amylase negative and citrate positive. it was predicted to he Bacilluss