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growing bacteria in a synchronised fashion

Edward Birge edward.birge at asu.edu
Wed Jan 28 10:21:19 EST 1998

It's not clear to me that your tactic of hard centrifugation will work to
break up clumps of bacteria. In order to separate mating E. coli, we
normally either vortex them on high speed for several minutes or use the Low
and Wood mating interruptor (a test tube mounted on the business end of a
saber saw). The interruptor only handles small volumes but needs only 7
seconds to work.

Guy Tremblay wrote in message <34C65B09.6E61 at medcn.umontreal.ca>...
>I am growing a certain number of tubes of bacteria. I have to induce a
>plasmid in those cells at a certain OD and collect them at an other one.
>Since I induce very early (0.15 OD600), it is very difficult to induce
>at the right time. In order to improve my method, I try to have my
>bacteria at about the same OD so that I have less OD readings to do.
>In order to synchronise my cultures, I measure the OD of a dilution of
>an o/n culture and strongly centrifuge my o/n bacteria to break
>clusters. This ensures that I will start my culture with
>about the same quantity of bacteria in each tube.
>Problem: Even taking these precautions, the bacteria have relatively
>different ODs after about 2hrs culture and it reduces the quality of my
>Question: Is there a simple way I could synchronize my cultures so that
>I can induce all of them at the same OD/time?
>Hope someone has the solution because I am quite angry against my
>undisciplined bacteria! Thanks in advance.
>Guy  Tremblay
>tremblgu at magellan.umontreal.ca

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