is there an experiment to show how do certain substances inhibit or promote bacterial growth?
There probably have been experiments for that purpose in the past, and it would be relatively simple to set up your own demonstrations.
Your controlled factors would be the type of bacteria used in your experiment and conditions such as the growth medium, amount of light, heat, humidity to which the bacteria is exposed. You would want to set up a number of identical test dishes and keep records for a few days of the bacteria's growth to establish your baseline data. The data should be the same from all of the dishes at this step.
The variable in the experiment would be the substances added to the growth medium after the bacteria has begun to grow. Make sure you record the amount of the different substances you use as you add them to your test dishes. Then continue your periodic recording of data such as the amount of bacteria present in each dish. The different data coming from the different dishes will indicate which substances are inhibiting or promoting the growth of the bacteria.