kparduc

Hello Microbiologists! I am having some issues with majority of my experiments. I am performing microbial assays on Pseudomonas aeruginosa with the use of CFU assays (incubation, serial dilution, and spot plating). However the bacteria are not growing after I incubate them for three hours. They are growing fine when I do not incubate them. Have any of you been experiencing similar problems with similar assays - perhaps with other microorganisms? Here are some details: - buffer pH is fine at 7.4 - we've made fresh stocks of our buffers (correct salt content and molarities) - we even tried it in PBS + TSB! Perhaps there has been a mutation in the bacteria that causes them to become vulnerable to environmental changes? We place them on ice after incubating them, wash them with a centrifuge, and the incubated group we put back in the shaking incubator at 37C. I hope someone can help me out! This has been bugging me for a while. - Kevin