Hi all,
I was wondering why for most of the analyses with bacteria, e.g. the determination of a bacterial growth curve, they are first grown overnight in broth and then diluted in new broth to measure the OD or their concentration at intervals. If I picked up a colony directly and let it grow in broth (without doing the previous overnight growth), wouldn't it be the same? and why?
Thanks
In addition to these mentioned by the others, using a overnight culture, you will standardize your inoculum to make your analysis repeatable and comparable, since the bacterium overnight cultures give a similar cell density and growth stage. If you directly pick up a single colony for your analysis, the variations of your inoculums could affect your results a lots and it is very difficulty to standardize them.
Hi,
Indeed, it's better to make a first growth before to make any analyses, especially when you start from an agar plate, to give a better fitness to your culture. You may have difficults with your OD (and with the experimental reproductibility) if you just pick up a colony and make your analyses with this first growth broth.
Hope I helped
Hi Silvia - Mélanie is correct, the problem with picking a colony is that the culture may go into a long lag phase before it starts growing exponentially and your growth curve may not be accurate at the early phases. Additionally it may take a long while to get to visible turbidity. But if you start from an overnight culture and dilute back, the cells should start growing at their exponential rate very quickly.
In addition to these mentioned by the others, using a overnight culture, you will standardize your inoculum to make your analysis repeatable and comparable, since the bacterium overnight cultures give a similar cell density and growth stage. If you directly pick up a single colony for your analysis, the variations of your inoculums could affect your results a lots and it is very difficulty to standardize them.
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