I'm doing the same with South Asian herbs! My advisor told me that IB doesn't allow bacteria from "inside" the human body (ex. mouth, nose, etc.) since it poses as a biohazard. But, I did my experiment based on bacteria I got from someone's hands — got the bacteria gram-tested and I got gram positive staph. aureus! It's a skin bacteria that's very common to see. And it's even better getting it from the hands because many people get sick for unhygienic reasons — dirty hands. I say try out classifying bacteria on your hands through gram staining and see where it gets you! Good luck. ps. Do you guys have any other experiments to refer to based on this? I'd really appreciate it. I'm having trouble finding some research already done on this.