GS microHero at
Mon Mar 17 14:15:04 EST 1997

Sean Tabacsko wrote:
> <<<<<<<<<<<<<<<<<<<<<<<PLEASE EMAIL DIRECTLY>>>>>>>>>>>>>>>>>>>>>
> Hello ,
>       I am working with clay as a transgenic substrate.I am testing to see
> if clay can retain plasmid DNA for later transfer to other recipient
> bacteria. I have concluded that the clay holds and transfers the plasmid
> DNA to the bacteria. I am using ampicillin resistance as an indicator for
> the experiment. I killed some E.coli MM 294 ampicillin resistant bacteria
> in clay in an oven at 130 degrees C mixed it with sterile LB broth and
> streaked some of this compound on an LB/Ampicillin plate to make sure all
> of the bacteria had died. Nothing grew. I used more of the LB broth, dead
> ampicillin resistant bacteria,and clay compound but this time added a non
> resistant MM 294 cell suspension mid log to the mix and set on ice for 20
> minutes and streked them on LB/ampicillin. There was growth which means
> there was a transfer of plasmid DNA to the non resistant bacteria that
> made them resistant and able to grow on the LB/ampicillin plate. I also
> checked that the mid log was still non resistant before adding it to the
> compound. I guess the questions I have are what sort of things do DNA like
> to bind to and why did the clay act as a good substrate. I would also
> appreciate any other thoughts or information that you can give to me
> conserning this project or substrates. I would like any help you can give
> me.
> Thanks in advance,
> Sean A. Tabacsko
> Center For The Arts And Sciences
> Saginaw, MI

Did you subculture the apparently resistant bug from the primary plate 
and verify that it was resistant after subculture? Did you control the 
experiment with clay which was NOT dosed with the resistant strain? This 
should show no growth unless the clay is in some way neutralising the 
antibiotic in the plate directly. You need to talk to a mineralogist 
about clays - they're basically molecular lattices, but some have the 
ability to expand and absorb water.

microHero at

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