Science Buddies: "Ask an Expert"

Hi-

I am having trouble with my science fair experiment. Several times I have asked about help with my project on the oil spills but were ineffective. I have decided to start fresh. I want to continue with the same topic but a different approach. I want to test what effect does changing the salinity have on the bacterium bacillus subtilis' degradation of oil. I want to reduce the concentration of salt in the medium used. However, how do I do that? Is it okay if I use motor oil in my experiment. I need help with the procedures as well? What specific materials do I need to conduct my experiment?

Note: I will test three conditions (optimal medium with oil, reduced medium with oil, optimal medium without oil).

Thanks,
Paige

Also, how do I grow the bacterium in a medium with in water supplemented with a specific mineral salts mixture containing the following amounts per L: K2HPO4, 3 g; KH2PO4, 1 g; NH4Cl, 0.5 g; NH4NO3, 0.1 g; Na2SO4, 0.1 g; MgSO4-7H20, 10 mg; MnSO4*4H20, 1 mg; FeSO4.7H20, 1 mg; CaCl2, 0.5 mg; pH adjusted to 6.8-7.0?