Re: [compost_tea] Re: Biti chamber removal

From: <soilfoodweb_at_aol.com>
Date: Mon, 4 Oct 2004 01:24:21 EDT

Please note that the question that asked about bacterial diversity in tea is
something that can only be answered using DNA analysis.

SFI tests total bacterial biomass, which relates to bacterial diversity. As
bacterial biomass increases, we know that bacterial diversity increases as
well.

But, there is no guarantee that it is beneficial bacterial diversity or
biomass that is increasing, UNLESS the conditions in the tea, or soil, or compost
are such that the conditions will select for the growth of the beneficials.

The habitat has to be maintained correctly. That means aerobic conditions.
Foods that help the beneficial bacteria, not the diseases. Nutrient
concentrations that enhance benficial growth, not pathogens.

Please understand that even microbiologists get a few things confused. Some
say that glucose, for example, is food for pathogens. BUT ONLY if other
conditions allow the pathogens to win.

If aeration sets up a condition where aerobic bacteria will be able to
out-compete the pathogens, then glucose will be used by the beneficials, not
pathogens.

Sugar CAN be used by pathogens, but it can also be used by beneficials.
OTHER FACTORS RATHER THAN JUST THE PRESENCE OF THAT SUGAR will determine who
actually uses that sugar.

Bacterial diversity is not easily measured. And really, only realistically
measured by doing DNA analysis. The newer molecular methods that purport to
give diversity assessment only asses a MINOR, insignificant set of species. For
example, FAME, PFLA, RAPIDs, and RNA tests can only separate perhaps 200
species of bacteria.

When you consider that microbial ecologists are now estimating that the total
number of bacterial SPECIES is well over 5 million, it is laughable to
suggest that plate count methods or molecular tests that can only distinguish 200
species could even come close to telling you anything about true bacterial
diversity.

So, we do the best we can with total bacterial biomass, and biochemical tests
to identify species. Or spend the money and do DNA sequence testing.

If you want FUNCTIONAL diversity, then maybe enzyme work would be useful.
But then you have to know the species of bacteria that those enzymes came from,
and which species were active, so you could predict how much enzyme would be
made tomorrow, and therefore, how much function will be performed tomorrow.

So, again, you have to do direct microscopy to determine if the organisms are
active, and so can produce the enzymes tomorrow.

No one actually routinely measures the change in bacterial diversity in any
environmental material, like compost or compost tea or soil as conditions
change. You don't have enough money, or graduate students, to answer those kinds
of questions.

It is easy to determine the change in total bacterial biomass, which relates
relatively straighforwardly to diversity. We just don't know which set of
species was selected, exactly.

But please understand that plate count methods don't even come close to
asessing total bacterial biomass - plate methods are invariably off by 100 to
10,000 times too low. Problem is, you don't know if they are too low by 100 this
time, or 1,000 or 2,000, or 5,000 or more. How can such a
variably-off-the-mark result be useful?

Direct assessments are the way to do this.

Questions? Please go ahead and ask, but ask in a pleasant and
non-confrontive, non-nasty fashion and I'll do my best to answer.

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
Soil Foodweb Inc., Oosterbeck, The Netherlands
Laboratorios de Soil Foodweb, Culiacan, Mexico
Soil Foodweb Inc., Jerome, Idaho
Soil Foodweb Inc., South Africa







Received on Mon Oct 04 2004 - 02:02:36 EDT

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