I am in need for a help pls having being not a microbiologist rather a nutritionist!
I am working on testing natural compounds on five different strains. I would like to prepare an inoculum isze of 106 cfu (10 to the 6), so what i did initially is i took 2 colonies and prepare an overnight culture broth. from this, I made serial dilutions and did the plate counting and simultaneously did the OD reading on the photometry. something however is always wrong with the reading or the colonies number when counting plates. the serial dilutions for the OD reading were from 101(10 to one) to 108 (10 to 8). i wanted to make a growth curve and find the dilution rate to obtain my inoculum size.
what did i do wrong?
then i thought of Mcfarland. to use it for this.. but is it reliable? do I use it and compare it to an overnight culture.I know that the culture should be during log phase, is 2o hours overnight culture reliable to be compared and diluted when compared to Mcfarland 0.5?
your help is greatly appreciated as i have been working on this since 2 days now!! am not a genius microbiologist and i am excited to learn
Thx in advance
Edit - I deleted your other thread in the general lab forum. Please only post your question to one forum. -Jerryshelly1