Antibiotics at heart of corn ethanol

Some US corn ethanol producers are using penicillin and three other antibiotics in corn fermentation process says Minnesota Public Radio.

Why? To ensure that the yeast they use in fermentation does not have to compete with naturally-occurring bacteria that wants the sugars in the fermenting mash itself.

I think that this matters on two counts:

One of the major revenue steams from ethanol producers is to sell the spent grain as protein-rich animal feed called distillers grains. There are strict limits in some countries on the amount of antibiotics in food produced by animals fed on this.

If the FDA, which carried out the study on distillers grains from 60 ethanol plants in the US were to strictly limit the amount of antibiotics in distillers grains,  the future of many of the plants in the US would be called into doubt.

The second, more far reaching effect is about antibiotic-tolerant bacteria. The FDA researched 60 samples across the US, and found Penicillin, virginiamycin, erythromycin and tylosin in the samples.


 Virginiamyacin plays an important role in human medicine for the very ill, it is used to treat endocarditis or meningitis. Here’s just how important in a quote from the University of Michigan.

Thenext AGP on the list is virginiamycin. Now virginiamycin is related toSynercid, which is an antibiotic that was just marketed for [vancomycin-resistant enterococcus]VRE in theUS in 1999, and this is after we went 10 years in US hospitals withouthaving any antibiotics to treat VRE. Yet here it is, literally, out inour food chain. Virginiamycin has been used in US animals since 1974.It was banned by the European Union in 1998. One study by L. CliffordMcDonald that appeared in The New England Journal of Medicinein 2001 found that about 17-87 percent of chickens tested insupermarkets in four different states, harbored this streptogram orquinupristin/dalfopristin-resistant organism.

My emphasis

By using antibiotics in these ways, isn’t it possible that the US corn ethanol industry is helping to breed new strains of bacteria that resist virginiamycin and other antibiotics that are used to save lives. Does your plant use antibiotics? How do you feel about it? Let me know.

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5 Responses to Antibiotics at heart of corn ethanol

  1. Mike 26 March, 2009 at 5:18 pm #

    It is important to look at the use of antibiotics, but it is also important to not jump too far ahead.

    Antibiotic resistance is incredibly complicated and drawing a line from DDGS or ethanol to humans with untreatable disease is difficult. Especially since the level of antibiotics in DDGS and/or used in the ethanol process is so incredibly small.

    Importantly, we also need to remember that anything using live cultures/yeasts/bacteria will have these problems. That means any current or future alternative fuel/energy source. Jumping to conclusions now could damage the entire sector.

  2. Simon Robinson 27 March, 2009 at 12:35 pm #

    Hi Mike,
    It is an interesting question isn’t it: A degree of fuel independence vs another assault on the effectiveness of antibiotics by businesses related to agriculture. Let’s be honest here, its about not thinking beyond the obvious. How about sterilising the corn before it is added to a clean reactor? Would boiling the mash solve the problem?
    Do you by any chance work at David & Associates , a pr firm with clients that include Aurora Co-Op which had an agreement to build 100-250m gal year ethanol plant at Aurora West with Aventine in 2006. If you do could you quantify “incredibly small” in terms of oz/gal ethanol. I’d really appreciate it.


  3. John 27 March, 2009 at 5:37 pm #

    The high temperatures used during the distillation process and the DDG drying process completely denatures the antibiotics so no active antibiotics are present in the DDGS fed to livestock.

  4. steve.eberhard 29 March, 2009 at 7:44 pm #

    Antibiotics aren’t the only way to eliminate the wild strains of yeast that develop during the fermentation process. The “tried and true” method of using antibiotics has the potential for causing antibiotic resistance in the yeast as well as devaluing the spent grain due to limitations on antibiotic tainted grain.

    Rather than using an expensive antibiotic to control these strains, new technology exists to wash the yeast with chlorine dioxide. The yeast does not develop resistance to the chlorine dioxide and ClO2 is organic approved, so the use of the spent grain as feed stock is acceptable.

  5. stefan 16 April, 2009 at 1:53 pm #

    Antibiotics are not fully broken down in destillation and drying of spent grains! You might regularly find residues with all the potential risks that bears! It is for a good reason that antibiotics are strictly banned from animal feed in Europe.
    Quite a good choice against unwanted bacteria in ethanol fermentation are hop products, naturally derived from hops, lat. humulus lupulus, the spice of beer. These liquid extracts are commercially available and are widely used in the US and also in Europe and Latin America.
    @steve.eberhard: In fact wild yeast can mainly be a problem when you recycle yeast from the process. Chlorine dioxide is a toxic chemical that has to be produced on site and is a bit agressive.

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