please help, paramecium

[pehp at erols.com]

Please read.
I am a high school student who is despartely try to do a science project. 
My only problem is I need to locate the name of a few different 
bacterium (which I could order from a Biological company). The bacterium 
must be able to live in water and it must harm a paramecium population 
but not destroy it. Please if anyone can help me, please email me at 
pehp at erols.com and write under subject Brittany: REPLY
Thabks