Aquaponics, worms and E. coli

[Kobus Jooste]

I have been made aware of a section in the latest newsletter of an aquaponics trainer making some rather interesting statements around the risk of introducing "deadly" E. coli HO157:H7 into aquaponics systems through the introduction of worms.

 

Like most promotional material, it contains enough reference to some form of correct base statement to make their argument appear compelling, but I have found the way that the section was written distressing in many ways.  On one front, we are trying our level best to ensure food safety and hygene in our units and to educate people on the safety of aquaponic production methods.  To have someone from within the community write something down the line of "if you dare put worms in your system you run a very real risk of introducing a deadly pathogen into aquaponics" is not conducive to building a fair and realistic impression of aquaponic production methods.  Worms in media beds have been in use for many years outside of the design of the group in question, with no reports of any health issues.

 

The inference made was that (without stating how many worm growers use cattle poo) red wrigglers are likely or potentially all grown in manure from corn fed cattle and this all contains the "man made" (?????!) strain of E. coli that will then most likely survive the transfer from worm to your system where you will contaminate your crops, your family or your customers.  If you are extra unlucky, a fly from a pasture containing corn fed cattle poo will also do the trick (then why bash the worms?) if they can make the trip in under 10 seconds. 

 

The article would have had more use if it simply said something down the line of "pick your worm supplier carefully - if you are cautious about E. coli, steer clear of using worm growers that cannot guarantee that their worms were not fed corn-fed cow poo from feedlots." I do not know what the ratio is of worm producers that potentially use this feed method compared to those that do not, but if it is the case that very few follow this practice, this article borders on reckless.  Then one can write follow-ups warning people on the next one in a gazilion risk such as a bird-flu contaminated duck landing in your fish tank.  As stated before, in theory, the conditions described in the text can potentially occur. Just as, in theory, a monkey can sit down in front of a typewriter, hammer away at it and write something recognisable. Not impossible, but likely? 

 

I wrote a blog a while ago about the responsibility of perceived role models in the industry related to statements made and perceptions created from a "credible" source.  This type of statement was exactly what I was talking about.  Not worth the negativety and not worth the potential bad press and poor PR for what many aquaponic producers see as a staple - media filled beds with worms in them (is there a reason for this?).  As a scientist, I would like to see some concrete evidence related to instances of the scenario described having been observed at worm farms and in aquaponic systems.  If no such data exists, is this statement fair and accurate? Why was it made? I do not want to appear to downright rubbish their concerns, but I will appreciate a percentage risk description to back up this claim.

[TCLynx]

Here is a site that has some generic test kits

filterwater

 

You are probably right about wanting to do daily tests to make sure not to miss when/if it goes away. 

 

I don't think you are likely to manage to test everything in one experiment and you want more than one control and more than one of each test example.

[David Waite]

Jon this just wont give you the ecoli test you are looking for. Ecoli is not in every manure or poo. You really need to contact a lab and get a slide with the live ecoli and submerse it in your test system. After a few days have the slide tested for any live ecoli. This will give a better result. I will bet a paycheck that the ecoli bacteria will be dead within 24 hours. I am guessing on this to be clear. heehe.

Jon Parr said:

I am willing to perform the test and control.  I'd like some suggestions and help. First off, would anyone other than me be interested in the results?  I suspect that a basic aquaponics system will naturally destroy E. coli.  I have nothing to support this hunch, and please don't think I'm suggesting that I know what I'm talking about.  I don't.  But from all the buzz about E. coli and Salmonella, I'm convinced there is no way to positively prevent it's introduction into our aquaponic systems. Minimize, perhaps, but not eliminate.  So why all the argument about how to prevent it? I think it more useful to practice common sense and hygiene, and study instead some vectors of control.  I'd rather trust that deadly germs are constantly dropping out of the air and contaminating my system and my system is capable of defense, than pray and hope I don't kill my family from one dirty little fly, or heaven forbid, a worm that didn't get a vinegar shower.

 

So, how's this for a start:  four identical barrel systems with gravel media, composting worms, ebb and flow, no fish (don't think it's necesary), heated to 70 deg. F, and growing lettuce.  I can build them all from scratch from identical materials, new water, new gravel, seed each one with equal amounts of existing system gravel to speed up cycling, and run a fishless ammonia cycle until all spikes have settled.  Then, find a feedlot, get some poo, make sure it has E. coli HO157:H7.  System 1) Control, add nothing except ammonia to keep biotics alive, 2) add scoop of poo directly to FT, 3) add scoop of poo to mesh bag with airstone, hang in FT, 4) add scoop of poo to media in GB.  Test daily the water, lettuce, and bioslime from each.  Publish progress.

 

Any results would not be gospel, of course, but might steer us down a better road than crossing our fingers.  If I do this, I need help with testing, and perhaps a source of E. coli laden poo.  I saw on the Friendly link that Sylvia posted that they have a lab that will test for $35 each.  At 3 tests on 4 tanks per day, that's about $3000 for a week.  I can't absorb that myself. Maybe someone out there has some information on a lab that would volunteer the tests, or we can chip in to pay for it.  Kobus, you're the scientist, any critique here is welcome.  I live in central California.  Maybe Peter Shaw has some connections with the college here for lab-work.  May I call the experiment Shitponics?

[Kobus Jooste]

Just a word of warning on the tests people want to run.  There are a myriad of  pathogens out there, and harmless E. coli by the bucketload.  I believe that there will be a need, as David pointed out, for a lab-based piece of work where specific pathogens are tested for.  These will likely not be released to the general public as they are potential biological weapons in the hands of the right (wrong?) person, and therefore to test the capacity of AP systems to deal with stuff such as discussed here may need close collaboration with the type of people that have access to and clearence to work with this stuff.  These are the types of research projects I believe the new Association should strive for though, so lets keep tossing in ideas and see where we can take it.

[Raychel A Watkins]

Take it from a Medical Laboratory Technologist that the bad E coli is not that easy to test for.  It involves special media and  a lot of time.  You wouldn't know where to do the test to find it anyway.  To think that the system would kill off the pathogen is a bit far fetched.  There is nothing in our system to do that.  What we have to do is practice good hygiene at all times.  We shouldn;t add things yhat contain manure no matter how old it is,  It is better to be safe than sorry.  

TC is very right in what she is saying.  E coli is the normal flora of our gut.  They check pools, drinking water, and lakes for this organism.  If positive to a certain level they assume that the water could contain other harmful organisms.  Any testing would have to be by a qualified person and I don't think you want to call in the health dept.  Another thing you would need to know how to read what the results meant.  I think you are headed in the wrong direction with this idea.  If the results are not the gospel truth then they are of no use.  Read the literature that has been put forth on this post and I think you will find your answer.  Food safety practices as any other farmer must do is the best way to go.  

[Raychel A Watkins]

David

No one is going to give anyone in the general public as Kobus said a pathogen  If you put it in your system it then would be contaminated.  You test the system or the produce for the pathogen in a qualified laboratory'  Organisms are grown out on special media to exclude all other organisms except the pathogen.  I promise you if you plated your fish water on regular media the results would scare you to death.  There are tons of bacteria in the water it is all in knowing how to figure out which are harmful.  In fact I thing I will plate some water out next week and take a picture of the plate to show you what I mean.  I really don't believe we are in any more danger of pathogens than any other farmer.  Besides if I tested my water what would that prove.  It would only be the results for my water not anyone else.

[Kobus Jooste]

Rachel - I agree with you, but in terms of a structured test, I would love to be able to address the issues around the aquaponic environment that we produce our crops in in terms of food safety criteria.  We all understand fully that the highest likelyhood of contamination will come from the operator of a system, and that the results from one does not represent AP in general, but there must be some way of starting to quantify what AP is based on in terms of typical microbes present in the system (a typical system).  It will be a daunting task with a lot of variables, but in the end, people are going to ask "what is in there" and we will then have to be able to provide some kind of guide.  In terms of pathogen survival, I do not recommend anyone tossing salmonella or dangerous E. coli strains into their systems at home, but I still would like to see what happens when a small research unit is set up and purposefully contaminated.  A time lapse analysis may be able to show IF it survives, and where it may find refuge (fish, plant roots, media, filter material).  This will help us all develop response procedures and better helath and safety understanding of how AP units respond to contamination.

[Raychel A Watkins]

Kobus It is a neat idea but would entail a lot of research.  It would probably best be done at a University that does aquaponics.  No one else could have access to the organisms.  It still would be quite difficult to do.

[TCLynx]

Who has some close ties to any of the University's doing aquaponic research?  Know any of the grad students or soon to be grad students that need a thesis project?

 

You are all right, this isn't a two month experiment.  It will probably be the work of years.

[Kobus Jooste]

The Association's chapter at large Chair is at Stirling University (or has close ties to it). Stirling has a long track record with aquaculture and may even have done similar things in pure aquaculture scenarios.  He would be a good source of info about places with a capacity and interest in UK / Europe.  I'll try and find out which U.S. uni's may have the same focus.

 

[Kobus Jooste]

I also recall a Aquaponics biosecurity and best practice type document originating from an Hawaiian institution.  Perhaps they could also be contacted.

Kobus Jooste said:

The Association's chapter at large Chair is at Stirling University (or has close ties to it). Stirling has a long track record with aquaculture and may even have done similar things in pure aquaculture scenarios.  He would be a good source of info about places with a capacity and interest in UK / Europe.  I'll try and find out which U.S. uni's may have the same focus.

 

[Teresa N Florida]

Hey TC,  

UF, University of Florida performs quite a bit of agriculture studies and posted http://edis.ifas.ufl.edu/pdffiles/HS/HS40800.pdf   related to Aquaponics. 

 

I don't know anyone directly at UF,  BUT most County Extension offices (in Florida), have ties to UF.  So if you are buddies with your Co. Ext officer that may be a way in.

[Jon Parr]

Thanks folks. Raychel, why wouldn't I want to call in the health dept? If they have the capacity to do the tests, maybe they are the best source for qualified testing? I am not a commercial grower, so I don't have to worry they will shut me down. I didnt expect to be able to run the tests myself, but cool if I could. I googled e. coli O157:H7 specific test kits, and there are quite a number of them. Here's a clip from a Dupont site:

The DuPont™ Lateral Flow System test is an immunoassay with built-in controls. It employs a unique combination of anti-E.coli O157 antibodies and a highly engineered colloidal gold conjugate coated on the surface of a membrane. The sample wicks up the test strip by capillary action. If E. coli O157, including O157:H7, is present in the sample, two red lines are formed.
Using the DuPont™ Lateral Flow System media for E. coli O157 reduces enrichment time to just 8 hours (for 25-g samples) or 10-15 hours (for 375-g samples. The media powder is mixed directly with sterile water for immediate use. You can also use the test with some samples enriched in standard media for 15-22 hours. After enrichment, you can choose to heat-treat the samples or test them immediately. Simply drop the test strip into an aliquot of sample broth, and read the results 10 minutes later. One control line is built into the lateral flow strip so you know the test has worked correctly. Two lines indicate a positive result. Test strips are stored at room temperature."

Only available outside the US, though, so maybe Kobus will have to run the experiment:)

I don't believe for a second that I would have to use a lab sample in order to find a strain with which to inoculate. If the specific tests work, then I should be able to find contaminated poo. The wild pigs crapping on the spinach didn't stop by the lab on the way to the field. If I can't find a "wild" sample, then we reconvene. I'm not expecting any results to be published in a scientific journal, but I might expect the scientific community to prove or disprove the findings of a layman.

Assuming I can find a lab that can test for the specific E. coli, and find a poo source, and take samples without contamination, then the results should be at least a starting point for further research, and a practical indicator of the susceptibility of our systems.

This whole thread got started because somebody made an unscientific warning that worms may be a vector of E. coli transmition (and indeed they may), when scientific research suggests that worms may in fact be a vital vector of E. coli control. Polar opposites, and yet I suspect both are true, the worm giveth and the worm taketh away. What I am suggesting is that perhaps our AP systems themselves are E. coli fighting machines, and all this doomsday talk of E. coli is moot. A test system may support or refute that suggestion, and I'm terribly curious to find out.