Skip to Content.
Sympa Menu

compostteas - [Compostteas] Response to Safety and E coli

compostteas AT lists.ibiblio.org

Subject: Compost Teas: 24 hour, EM, IM, BD & fermented plant extracts

List archive

Chronological Thread  
  • From: "Soil Foodweb, Inc." <info AT soilfoodweb.com>
  • To: "Jeff Lowenfels" <jeff AT gardener.com>, "Compost tea List Serve" <compostteas AT lists.ibiblio.org>
  • Subject: [Compostteas] Response to Safety and E coli
  • Date: Mon, 17 Jun 2002 18:04:02 -0500

> This is in response to "Safety and E. coli" from Will
> Brinton
>
> No one is saying that ALL that has to be done is aerate
> tea and all will be fine.
>
> What is the first critical thing (which is an indicator
> there are other critical things as well) about compost
> tea? For the umpteenth hundreth time......
>
> You have to use good compost.
>
> By definition, good compost will not have E. coli.
> Temperature, heat and the huge diversity of bacteria,
> fungi, protozoa and nematodes all work to remove E. coli,
> and any other human pathogen from the compost. With worm
> compost, passage through the earthworm digestive system
> removes E. coli. Mechanism? Ask Clive Edwards. I'm
> working on assessing of the microbiology of the worm
> digestive system, showing that E. coli is consumed and
> outcompeted by the other organisms in the worm digestive
> system. Lots of protozoa in worm digestive systems is the
> most likely mechanism.
>
> So, multiple mechanisms of removal, suppression,
> prevention, inhibition, etc. Just like in GOOD tea, it is
> the right organisms, in high numbers, growing and
> out-competing the bad guys that result in no E. coli.
> ---------
> When it is stated that "lots of available sugars are
> present", what does that mean?
> It means that bacteria will grow very rapidly, as long as
> temperature, moisture, etc are also right, which is
> typical when tea is being brewed.
>
> - With me so far? Do you agree with this so far?
>
> What happens when bacteria grow very rapidly? They use up
> oxygen, right?
>
> - Anything wrong with what I'm saying so far? Any part of
> this you disagree with?
>
> If oxygen is used up by rapid bacterial and fungal growth,
> then the tea is no longer aerobic. Correct?
>
> So when you say lots of sugars added, it means the medium
> will likely become anaerobic, unless you do something to
> prevent the oxygen in the tea from dropping to low
> levels.
>
> The something else is: Aerate the tea. In every instance
> that we aerate well enough to offset bacterial and fungal
> depletion of oxygen when growing rapidly on added sugars,
> then E. coli is out-competed, inhibited and prevented from
> growing by all those other aerobic organisms.
>
> You could try running this experiment yourself, instead of
> arguing endlessly about it. Get an oxygen probe, and make
> sure you keep the tea aerobic the entire time, regardless
> of whether you add sugar or not. Test for E. coli at the
> beginning of the experiment, and at the end. Prove it to
> yourself. If you don't start with E. coli in the compost,
> you can't grow E. coli whether you go anaerobic or not.
> Even if you do have E. coli in low numbers, the
> competitors prevent its growth, as long as conditions stay
> aerobic.
>
> Huge numbers of E. coli in the compost? It's not
> compost.....
>
> If E. coli were able to grow any time sugar was present,
> you wouldn't be able to eat or drink anything you left out
> on the counter for more than 20 minutes. Thank goodness
> E. coli and other human disease organisms cannot compete
> with normal aerobic bacteria. Or we'd all be dead.
>
>
> -----------
> You can't rely on the work used to convince the NOSB in
> their latest ruling about compost tea. The data reported
> in those experiments either purposefully let the medium go
> anaerobic - and oh, surprise (dripping sarcasm in my voice
> here) - E. coli was found to grow! Using manure mixed
> with wood chips as the starting material, as far as I can
> tell, E. coli grew. Oh, gasp! Manure has high numbers of
> E. coli. Composting results in them being killed. But it
> has to be aerobic composting. Putrid conditions allow E.
> coli to win. No surprise here either.
>
> In the other set of data, the oxygen values reported in
> the paper cannot possibly have been generated from the
> same tea where E. coli was growing. Un-composted material
> was used, and almost undoubtedly, the medium went
> anaerobic. E. coli, if present, and without any
> competition, will use those sugars, and drive the medium
> anaerobic. These results are no surprise to anyone.
>
> The point is, when conditions ARE maintained adequately to
> select against E. coli, and you have lots of beneficial
> organisms present, E. coli does not grow.
>
> In the NOSB ruling, the phrase about sugars, molasses and
> soluble carbon source should be dropped. It is not
> needed, as long as the ruling about using good compost -
> by definition without E. coli - is maintained. No E.coli
> in the compost, no E. coli in the tea.
>
> Focus on the proper thing to be regulated.
> -----------
> I think arguing the point whether E. coli can grow
> aerobically, when it is growing on a selective medium, is
> nonsensical. Why do you think the specific conditions to
> grow E. coli have to be so particular when plate media for
> E. coli are used? And even then, E. coli tends to be
> pin-point colonies when grown under fully aerobic
> conditions, even on media that prevents the growth of its
> competitors. When E. coli has to compete with lots of
> other growing aerobic bacteria, the aerobic bacteria win.
> ----------
> I am sorry to hear about your friend who sprayed tea and
> got an eye infection. But I doubt that it was truly
> compost tea. If you examine the conditions under which
> the tea was produced, I expect there would be some truly
> questionable production conditions. First, the inoculum
> of E. coli had to come from someplace, and therefore the
> compost was not likely compost. Second, for E. coli to
> grow to high numbers, the tea would have to have gone
> anaerobic. Addition of too much sugar, and/or not
> aerating enough, would allow E. coli to out-compete the
> aerobic organisms that would normally suppress it.
>
> Just as with any aerosol, whether it is a mist of rain
> water or cola, don't allow it to get it in your eyes. I
> know people who drink compost tea everyday, but they are
> very careful about the compost they use. I know people
> who bathe in compost tea, but they wash their hands before
> eating anything.
>
> Common sense is necessary.
>
> Elaine Ingham, M.S., Ph.D.
> President, Soil Foodweb Inc.
> Affiliate Faculty, Graduate Research, Southern Cross
> University, NSW
>




  • [Compostteas] Response to Safety and E coli, Soil Foodweb, Inc., 06/17/2002

Archive powered by MHonArc 2.6.24.

Top of Page