Re: [compost_tea] Re: SFI requirements

From: <soilfoodweb_at_aol.com>
Date: Tue, 15 Mar 2005 05:30:12 EST

 
Hi Dennis -
 
The methods are explained on the SFI website, in the section, The SFI
Approach.
 
DIC stands for, Differential Interference Contrast Microscopy. It uses
shadowing methods to emphasize surface characteristics of the organisms being
examined. It has to be used to assess fungal biomass, and makes ID of nematodes
much, much easier.
 
FITC stands for fluorescein isothiocyanate. This is a fluorescent protein
stain, and as such, makes protein glow a fluorescent green color. It is the
way to differentiate clay from bacteria, as clay particles do not hold enough
protein to produce the intense fluorescence that bacteria will give. Thus,
it is the preferred method for assessing total bacterial biomass. Other
people use other fluorescent stains, and really, any of these protein stains work
equally as well.

 
FDA is fluorescein diacetate, which is an activity stain. This stain is not
used by organisms using anaerobic metabolism, and thus is a good way to
assess aerobic, active biomass. This material is not fluorescent when the two
acetates are attached to the fluorescein. FDA has to be actively transported
across the cell membrane, which takes energy to do, and requires an intact
living cell. Once in the cell, the FDA is hydrolyzed, using any of a large
number of different esterase enzymes. This frees the fluorescein, which
accumulates in the cell, resulting in uptake of light at one wavelength, with
consequent release of light at a longer wavelength, which is the fluorescence that
we see. We measure the length and width of the organisms that are fluorescing
 in order to then determine active biomass of bacteria, or fungi.
 
These methods are in the soils methods books, and are published in the
scientific literature. Again, they are in my publications, and that list can be
obtained on my website. Most of the publications can be obtained on-line, or
through inter-library loan.
 
Direct determinations mean use of direct observation, with microscopes.
 
Why not learn to use the small microscopes so you can do your own
assessments? There is a book we have put together so you can learn on your own, or
come to a day class. We offer the classes at the Corvallis lab, the New York
lab, the Australia lab and the New Zealand lab. The Canada lab will offer the
class soon as well.
 
Hope this helps -
 
Elaine
 

--- Hello Elaine, Relative to your message 12091 (previous message)
and your offer to explain methods below, where do I find methods
DIC, FITC, and FDA? Are they in Water and wastewater analysis or
BAM OR How about just sending me an e-mail with them enclosed? Also
what do those abbreviations stand for. Am I correct in assuming
direct determination is using direct microscopic methods? I have no
agenda. Just TRYING to get my ACT to a point I can verify it's
quality. Dennis Kemnitz in KS



Elaine R. Ingham
Soil Foodweb Inc., Corvallis, Oregon
Soil Foodweb Inc., Port Jefferson, New York
Soil Foodweb Institute, Lismore Australia
Soil Foodweb Institute Cambridge, New Zealand
Laboratorios de Soil Foodweb, Culiacan, Mexico
Soil Foodweb Inc., Jerome, Idaho
Soil Foodweb Inc., South Africa








Received on Tue Mar 15 2005 - 07:20:54 EST

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