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> bionet/microbiology #11389, from YoungSA at AgResearch.cri.nz, 816 chars,
Mon 20 Sep 99 20:52:01
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> Article: 14471 of bionet.microbiology
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> From: YoungSA at AgResearch.cri.nz (Sandra Young)
> Newsgroups: bionet.microbiology
> Subject: Recipe for Humic acid-vitamin agar
> Date: Mon, 20 Sep 99 20:52:01 GMT
> Organization: AgResearch, Lincoln
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>> Can anyone provide me with a recipe for Humic acid-vitamin agar for
> isolation of actinomycetes from soil? (or a reference?)
>> Thanks
> Sandra
Hello Sandra.
Humic acids are normaly extracted from soil by boiling up with NaOH,
filtering and then precipitating with alkali. I can't think of a good
reason for actinos being especially fond of this brew except that they
might like the slightly excessive high pH.
The classic brew for actinos usually includes chitin (or possibly acetyl
glucosamine if you want something soluble) and the antibiotic producing
companies usually treat soil samples with "good ole" phenol first to
knock out the pesky bacteria and fungi.
Funnily enough (despite what I have just written above) an old student
of mine (Mike Greaves - run a web search on him - last known at Long
Ashton, Bristol, UK) did some work on cold water extracts of soil -
sterilised by filtration which were also pretty good at growing
actinos.
An ecological aside on this (I have been running soil microbiology
undergraduate practical classes for 37 (yes 37) years) was the effects
in UK of the extreme drought of 1976-77 when we had a very dry summer
followed by dry autumn, winter, spring and another dry summer. We
collected soils for our practical class in the October and (using weak
tryptone agar) grew virtually nothing but actinos - we were scratching
about to find a single bacterial colony. A bad practical for the
students but a big lesson for anyone worried about biodiversity !!!!!!
Best wishes,
Dr Peter Harris,
Dept of Soil Science,
The University of Reading,
Whiteknights,
Reading,
UK
AKA <P.J.Harris at reading.ac.uk>
