Expert: Walter Hintz - 5/10/2008

Question
Hi! We have a 8 day old crop of bacteria we grew in the agar gel in 12 different
petri dishes. Is this bacteria harmful to our health and is is ok to breath? How
should we dispose of it when we are done watching the growth? Thank you,
Jennifer

Answer
Hi Jennifer
Without examining every colony on a petri dish it is hard to tell which are harmful so it is a good idea to assume that there are pathogens there and do not get them on your skin.  Unless you see fuzzy growth you would not be inhaling anything.  When I worked in a microbiology lab we autoclaved old cultures.  In my college labs we put them in a biohazard bucket and I do not know where they go.  I suppose if you cannot incinerate them you could boil them or even bury them.