I did a test which involved growing e. coli on a petri dish. I did not dilute the sample, and this resulted in growing hundreds of small, overlapping colonies. However, they still can be counted, but it has been tedious work. Does anyone have tricks for counting small colonies? Also, I've read people will just write >300 if their colony count is too large. Is this data sufficient? I need to compare the colony count for several petri dishes and they all have quite a lot. If i just write ">300" for 80% of my data, it won't be a very good comparison. Can anyone help me out here?
Divide the plate into equal sectors. Count one sector as accurately as you can then multiply that number by the number of sectors. This assumes the colonies are roughly equally distributed.