1. Study the effect of industrial antibiotics on microbial growth

2. Antibiotics are chemical substances that are produced by a microorganisms that kill another ones. But these chemicals are used without the use or inoculation of the producer organism. Antibiotics are powerful medicines that fight bacterial infections. Used properly, antibiotics can save lives. They either kill bacteria or keep them from reproducing.

3. Organism could be sensitive (susceptible) or resistant to the antibiotic. One of the most widely used methods to determine the susceptibility of microorganisms to antibiotics (antimicrobial agents) is the disc agar- diffusion method.

4. Experiment : Study Antibiotics antagonism

5. 1-Dip the sterile cotton swab into the culture to be tested. 2-With the swab, cover the entire surface of a nutrient agar plate. 3-Let the plates dry at room temperature for several minutes. 4-With the disc dispensers, apply four antibiotic discs to the plate. 5-Incubate the plates for 1-2 days at 37°C 6- look for bacterial growth inhibition zone around each disc.