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Re: question for elaine



Hi Roberto -

You said:
It seems to me that aeration will select for the aerobes (both
beneficial and harmful) and minimize the anaerobes (both
beneficial and harmful). Would this be right?


When we look at the beneficials in soil or compost, there are not many aerobic species that will cause disease that do well in the conditions in the tea brewer. 

In general, the disease-causing aerobic organisms require high nitrate levels.  That will not happen in your tea maker.  Or, we have never seen it happen.  So, the majority of disease-causing aerobes will not grow in the tea.

Are they there?  Probably, you could detect them, if you used a selective medium and plated very low dilutions.  BUT, they are present in such low numbers, that they are not capable of winning in the competition for plant exudates or surface area.  The plant does not put out foods to feed these bad aerobes.  So, in low numbers because the many limitations of their growth in the compost tea maker.

A couple people have said that E. coli can grow under aerobic conditions.  Sorry, only in the lab.  We put very selective conditions on E. coli to get it to grow in the lab in normal oxygen concentrations.  It cannot compete when there are lots of aerobic competitors around. 

The disease causing pseudomonads, for example (many have been re-classified into new genera, but I'll always consider them as pseudomonads), require high iron, or low calcium or certain boron stress in the plant in order to be able to attack.  If we are adding kelp, we are alleviating those lacking conditions, and the diseases can't outcompete the beneficials.

Do we need the beneficial anaerobes?  Not in large number.  We don't want the soil to ever be anaerobic.  Do the anaerobes survive the aerobic conditions?  Yes, in low number, in dormant stages.  We don't need to be adding anymore..

Well, we do have the fermentative anaerobic situation to consider.  When feeding silage, for example, we should have high numbers of these fermentative anaerobes.  They will be in the manure then.  They go to sleep during aerobic composting..  They are in your tea in very low numbers.  Spray your plants with these teas, and the organisms your cows need to help them digest that clover, alfalfa, etc will be on the surfaces. 



It would be useful to get some ballpark numbers, like the ratio of
beneficial to harmful aerobes, and the ratio of beneficial to harmful
anaerobes, if you happen to have these figures.


This requires that we know the function of all the species in soil or compost.  We don't have a handle on that yet.  We have a list of 40,000 plus DNA sequences. We can tell you species diversity, but we do not know which sequence corresponds to which function.  Well, for some sequences, we do know function, but we have a ways to go yet. 

With plate count aerobic versus anaerobic assays, there's a real problem.  The same medium is typically used in both aerobic and anaerobic plates.  Half the plates are put in elevated CO2 atmosphere, not truly an anaerobic condition.  So there's problem one with this assay. 

Many bacterial species can grow in aerobic conditions, and in anaerobic conditions.  So, some number of the bacteria growing on the "aerobic" plate ALSO grow on the "anaerobic" plate.  If you have nearly the same number of aerobes as anaerobes, does it mean something bad? 

No.  Not at all.  There are no data showing that as a valid conclusion that I am aware of.  Nearly everything was a facultative anaerobes, that's all that means, perhaps.  Is that bad?  No.  So what does that ratio mean?  Nothing.  Flat out, nothing.  Meaningless. 

Nearly 99.99% of the bacterial species in soil do not grow on any plate medium.  So, are they beneficial or not?  We don't know..  Most anaerobes cannot be grow on any medium.  So, until microbiology gets a bit further along, we have to go on the basis of the activity assay that SFI does.  ALL aerobes take up FDA.  Anaerobes do not.  Facultative anaerobes growing aerobically take up FDA, but when they grow anaerobically, they do not.  So, there's our way of knowing aerobic/anaerobic. 

And now, we have to figure out their functions - bad or good?  Relative to which plant?  Which soil?  Which climate?   There's a bit more research needed......

We can ID for you the beneficial bacteria we do know what their sequences are, or that we know grow under certain conditions.  So, SFI has started doing that.  We'll be accumulating data on this question pretty rapidly. 

So, stay tuned on this too.....


It is not clear yet how the choice of food selects for the beneficials
and excludes the harmful.

Just like people.  Put a plate of ethnic food out, and you get mostly certain kinds of people growing there.  There are the same selective forces with critters. 

Aerobic conditions, high growth rates, humic acids, good sets of balanced micronutrients from kelp, all help set the stage for the good guys.  We can't assay everything, but what we see is that the really beneficial species grow very, very well when you have the right foods and conditions.  The human pathogens just can't compete.....

We've been talking of molasses, for instance. Does molasses
select for beneficials, against the pathogenic and other harmfuls?
How?

The specific sugars that the good guys like.  Some people have said that E. coli likes high sugar conditions.  Only if you let the tea go anaerobic.  Only if you don't have lots of other bacteria that are better at grabbing the sugar when the oxygen limits E. coli growth.  So, if you make certain the other conditions are also limiting the bad guys, then the complex sugar mix in molasses really helps the beneficials.

Also, since the aerobic conditions minimized the beneficial
anaerobes, how do we put these back to the s


EM inoculum.  Or use non-stinky manure. Which only occurs if you feed your cows the right stuff.....    :-)

Elaine Ingham
President, Soil Foodweb Inc.
www.soilfoodweb.com