[Microbiology] Re: isolation of bacteria
(by bactitech from nospamhortonsbay.com)
Sun Sep 21 01:32:17 EST 2008
Three weeks of incubation for bacteria seems excessive. I know nothing
about DNA extraction or environmental bacteria, but I do know that
bacteria go through growth phases. Eventually they will be living in
their own filth and die off. Why did you decide on three weeks? Are you
inoculating into anything nutritional? Are you passing your growth into
new broths along the way? Why not streak the water onto solid media and
see what grows? May have to do dilutions until you find a dilution where
you can get isolated colonies. Pick the colonies individually, one at a
time, and put them into their own broth, and then you will have pure
cultures. Why work with mixed cultures?
I have no idea what media you would use for this - just putting the
concept out there. I know we do water cultures from time to time and use
something called Standard Methods agar. We buy the deeps commercially.
We are not dealing with this type of water, however. We're culturing
distilled water and checking for contaminants.
What temperature are you using? I would think environmental bacteria
need cooler temperatures than, say, 35 degrees C which is what we
incubate human medical bacterial specimens at. Again, I am a medical
micro person - NOT an environmental one.
Robert Koch discovered solid media in the 1880's. This is how he got a
leg up on Louis Pasteur, who never figured out how to move beyond broth
cultures and work with pure cultures. Solid media is the foundation of
Judy Dilworth, M.T. (ASCP)
"RUTH SIELE" <ruthsiele from yahoo.com> wrote in message
news:mailman.82.1221933057.29717.microbio from net.bio.net...
I am trying to isolate the bacteria from brackish water. I incubated the
brackish water for three weeks. When I centrifuge the culture after
three weeks, I couldn't get any pellets to extract the DNA. I streak
them in LB plates but it will be culture dependent.
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