Bacterial infections are a fact of life in the ethanol production process. The reality is, complete sterilization is simply not practical, according to Kevin Kauers, senior research scientist for North American Bioproducts Corp. Kauers was one of several people who gave presentations on bacterial control at the 2012 International Fuel Ethanol Workshop & Expo, held June 4-7 in Minneapolis.
Because bacteria competes for yeast and sugars, reducing yield, even a small infection can hit the bottom line hard. At $2 per gallon of ethanol, a 50 MMgy plant would lose about $500,000 a year with only a 0.5 percent loss in yield. That goes up to $1 million for a 1 percent loss and $4 million for a four percent loss, illustrating why it’s so important that producers remain proactive in fighting contamination, Kauers said.
There are three options for ethanol producers looking to control bacterial infections, according to Brian King, lab manager for Ferm Solutions Inc. The first is an application of 0.5 to 2 parts per million (ppm) of conventional antibiotics. Nonantibiotic options include new natural products, hops, chlorine dioxide, hydrogen peroxide, bleach, para-acetic acids and more.
BetaTec Hop Products has seen significant growth in the use of alternatives to antibiotic products in the U.S., said Lloyd Schantz, executive vice president of the company. Out of about 200 ethanol plants in the U.S., more than 60 are using products marketed by BetaTec or its competitors, some in combination with antibiotics and others in place of antibiotics. As the use of antibiotics in the ethanol production process increasingly comes under scrutiny, U.S. FDA regulations may become stricter, prompting even more growth. However, Schantz predicted future changes will be driven by the customers of distillers grains, who he expects react faster than the regulatory agencies.
For example, Poet LLC announced a year ago that it was selling certified antibiotic-free distillers grains. The move was significant, considering Poet is the largest dry-grind ethanol producer in the world. The company spent a few years developing and testing a new process that eliminated the need for antibiotics. Although the process has been installed at all Poet plants, only customers specifically requesting it will receive certified antibiotic-free distillers grains, the company said.
DuPont markets its trademarked FermaSure, patent-pending, stabilized chlorine dioxide products, to ethanol plants around the world, according to Eric Sumner, business leader for the company’s FermaSure antimicrobials business. Since it was launched at the 2007 FEW, DuPont’s FermaSure is now used in about 50 U.S. ethanol plants, including Poet’s facilities. “DuPont has certainly seen very strong growth in our FermaSure products sales, and away from antibiotics,” Sumner told EPM. “Most of our customers do not use any antibiotics. Some customers choose to use both FermaSure stabilized chlorine dioxide and antibiotics.” The company believes this is due to the practice of rotation to prevent development of resistant bacteria strains, something that it says is not necessary with DuPont’s FermaSure.
Ferm Solutions is looking to nature to develop antimicrobial products for the fuel ethanol industry. The company has, so far, selected 23 natural exudates for commercial application, including one called Naturyl, currently undergoing trials at both batch and continuous ethanol plants, Kauers said. The data shows that, under high bacterial pressure, applications of 2 ppm Naturyl can result in yield increases. The result of one trial showed that using the 100 percent natural product in a bacteria-infected fermentation resulted in 12.893 percent yield, compared to 12.784 percent yield in the control with no bacteria added. The treatment with bacteria, but no Naturyl, yielded only 8.833 percent. “Naturyl appears to be a viable alternative to antibiotics for controlling bacteria in fuel ethanol applications,” he said, adding that the company is now working to gain regulatory approval for use in the fuel ethanol industry.
Illustrating that bacterial infections aren’t a corn-ethanol problem alone, Jadyr Oliveira, managing director for Prozen Biosolutions, spoke at FEW about the Brazilian company’s efforts to develop Biozyn, a bio-based antimicrobial. The industry has been working on the problem for four or five years because dried yeast, a coproduct of the sugarcane-ethanol production process, is marketed to the animal industry, he said. Moving away from antibiotics is a challenge because those products are extremely efficient and a high sugar load makes sugarcane ethanol very susceptible to bacteria, he said. Prozen’s Biozyn works well in sugarcane ethanol production, however, and has also shown excellent results in industrial trials at corn-ethanol plants which, in Brazil, produce high-quality ethanol for the pharmaceutical industry.
Author: Holly Jessen
Features Editor of Ethanol Producer Magazine