What Exactly are Coliforms?

Coliforms are are group of closely-related organisms. For the most part, Coliforms are relatively harmless, and occur naturally in the gastrointentinal tracts of most animals, as well as in the soil and the water. When referring to Coliforms, we’re generally referring to 4 main organisms; Escherichia, Klebsiella, Enterobacter and Citrobacter. All belong to the Enterobactericeae family, which, as we just stated, reside in the gastrointestinal tracts of humans and other animals.

The reason Coliform testing is so important is because it has traditionally been an indicator of how hygenically the material in question was handled. From harvesting (if it’s a plant), to processing, to delivery to you as a raw material or finished product.

High Coliform counts typically indicate unsanitary conditions or poor hygenine. So, does the mere presence of coliforms indicate fecal matter is present in a material?

The short answer is “No.”

Do Coliforms Automatically Indicate Pathogens or Contamination?

Coliforms do exist naturally in the environment. Testing for Coliforms does not automatically indicate fecal contamination, but a high Coliform count often results, when further testing is conducted, in detecting fecal matter in the material. This is why the FDA requires all material intended for consumption to be free of any E. Coli, one of the more non-lethal, but troublesome coliforms to humans.

Also, it’s important to note that it’s not just human fecal matter that is being detected. Since any warm-blooded animal is going to have coliforms residing in their gastrointestinal tract, there are many ways for material to get contaminated. Coliform presence doesn’t automatically mean that pathogens are present. High levels of coliforms does increase the risk of foodborne illnesses, but a high level of coliforms generally indicates hygienic conditions during harvesting, processing, and shipping of raw plant materials.

Let’s use an example of a plant that is being grown on a farm. If manure is being used to help the plants grow, studies have revealed that E. coli can live for extended periods of time in both water and manure.

“Studies have indicated that E. coli can survive for extended periods in manure and water (7, 11). We have demonstrated that lettuce grown in soil containing contaminated manure or irrigated with contaminated water results in contamination of the edible portion of the lettuce plant.” (https://aem.asm.org/content/68/1/397)

That means that is manure is being used on plants intended for consumption, the possibility of those plants being cotaminated with E. coli goes up considerably.

Let’s then say that the farm also keeps animals, and those animals live in a barn. Let’s say that barn is also where plant material is dried. If the same people harvesting the material were handling animals, or in a place where animals or other livestock were, E. coli can contamination can easily transfer.

Or, if water that has been contaminated with E. Coli is used to water or wash the plant material, this is another source of potential E. coli contamination.

And, the list goes on. If the plants are watered with “gray” water, if the plants are watered and/or washed with well or pond water that has any kind of wildlife use or visit it, if wildlife visits the plants while they are growing, and feed on the plants, or brush them as they pass; those are all common sources of contamination.

Is There Any Way to Kill E. Coli?

Luckily, E. coli is easy to kill. Subjecting E. coli to an INTERNAL TEMPERATURE of 148°F for three minutes will kill 99.99% of E. coli and Salmonella. Subjecting E. coli to an INTERNAL TEMPERATURE of 160°F for 14 seconds will kill 99.99% of E. coli and Salmonella. Please note that INTERNAL TEMPERATURE is critical for success. If you have a thick rooty plant, you will need to grind those roots as finely as possible, or at least to the final size they will be in whatever product is being made from them.

The FDA allows DEAD E. coli and Salmonella to be present in material intended for consumption. Through the PCR testing we do here that only takes 24-48 hours to see results, since it’s a DNA test, it will only show whether pathogens such as E. coli and Salmonella are present; it won’t tell you whether or not they’re living or dead.

Obviously, the best material to work with is material that was never contaminated in the first place. Many suppliers are able to successfully work with their growers to ensure more sanitary conditions are followed when growing, harvesting, and processing material that will eventually be meant for consumption.

We offer small scale sterilizing of plant material up to 1000KG, but we are mostly in the business of testing for Coliforms and other pathogens in any material we are provided with.

How Does This Relate to the Aerobic Plate Count on My Results?

The easiest way to think about your results, is to put the results into to two main groups. The first row is the AEROBIC PLATE COUNT, which measures ALL of the biological activity of the material. This includes all bacteria, fungi (molds) and yeast that will grow in an aerobic environment. We do Aerobic Plate Count tests are 35C because this helps us detect the organisms that are most-likely to exist on or in humans.

The YEAST and the MOLD content are the two main types of fungi that are typically found in plant material. In general, the presence a larger-than-usual amounts of yeast and mold indicate that the material being tested is not very fresh, or was handled poorly while it was being harvested and processed. Is the material was piled high as it was being harvested, plant material at the bottom of the pile will begin to decompose quite quickly. If the material was held in a dark, damp place for a period of time, this encourages decomosition of the plant material.

Since yeast and molds occur naturally everywhere in nature, fresh plant material is extremely suseptive to deterioration. In fact, the pH requirement for mold growth is quite a wide range; from pH 2 to greater than pH 9, and at temperatures between 50 – 95 degress Fahrenheit.

It’s important to note that the moment a raw material is processed using extraction methods or placed under extreme heat will kill most of the yeast, fungus, mold, and everything else dangerous in a material. Subjecting the material to INTERNAL TEMPERATURES of 212 degrees Fahrenheit (100 degrees Celcius) will also kill most pathogens, yeast and mold.

What is a Safe Level of E. coli in My Test Results?

There is no “safe level” of E. coli in your test results. We get asked nearly every day if a clients test results have “too much” E. coli or not. It’s a yes or no question, and there is no gray area. Either your material is contaminated with E. coli, or it is not. We sometimes provide numbers instead of a “Yes or “No” result because it is more accurate. On several of the FDA-approved testing methods, there is a lower detection limit for E. colil of < 3. We sometimes include that number instead of a “yes” or a “no” to be as accurate as possible. We are telling you that we did not detect any E. coli, but there could be a single cell of it hiding out somewhere in your material. That specific testing method we used (typically FDA-BAM), has a lower detection limit, although extraordinarily small, so it does leave the tiniest, microscopic margin for possible error.

At the same time, a < 3 CFU/g result for E. coli is acceptable for consumption by the FDA. The ‘Coliform Microbial Density’ for drinking water in most of the world must be completely free from any E. coli colonies whatsoever. Bathing and swimming pool water can have about 200 colonies, and recreational water about 1000 colonies.

REFERENCES:

https://aem.asm.org/content/68/1/397

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2672.2000.tb05335.x