Why am I getting smears instead of colonies during tesing the CFU using pour plate method?

27 October 2023 1 7K Report

i have tried to check the CFU of 6 species of bacteria using pour plate method, and all the bacteria had some smeared colonies within the agai medium.

Chandrika Nanayakkara

Two possibilities: (i) your culture is too dense and need dilutions (ii) the bacteria are highly motile- need to dry the plates to reduce the motility. Employ spread plates that can be dried before use. Pour plates encourage condensation of water inside the plate.

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