hello,

im trying to do CFU experement (CFU vs OD) for Sulfolobus acidocaldarius. I'm plating 200ul from each 10-fold serial dilution, from 10^-1 to 10^-6. interestingly all plates get condensed growth at 10^-1 (which is expected) but no growth\colonies in the rest of the dilutions :( or I get inconsistent growth meaning some plates will grow colonies in all dilutions others only in 10^-1. I've repeated the experiment three times but I can't seem to figure out the reason causing the inconsistent development of colonies. the media I'm using is basal salt media with gelrite. plates are incubated at 75C in a box containing wet towel and it is covered with an autoclave bag to minimize evaporation. and I do make sure to mix the diluted culture when doing the serial dilution.

what do you think is going wrong?