Keeping Bacteria At Bay

Producers modify antimicrobial protocols in response to multiple process and input changes, including new yeast and enzyme offerings, as well as high-protein feed production.
By Susanne Retka Schill | April 13, 2021

While many aspects of the battle against bacterial infections have improved, the evolving process at ethanol plants continues to introduce new challenges. New yeast, new enzymes, new feed coproducts, new cleaning solutions, new tools are all impacting antimicrobial regimes in plants.

Long the mainstay of bacterial control in fermentation, antibiotic use at ethanol plants is order of magnitudes less today than it was when Jenny Forbes started working at an ethanol lab in the early 2000s. Forbes is vice president of products and services for Phibro Ethanol Performance Group. Over the years, she’s learned the shotgun approach—throwing more antibiotic in whenever infections threatened—is not necessarily the best approach.

“Rather than overuse a product that’s not doing the job for you, use the right amount of the right active,” Forbes says. In analyzing bacterial response to different antibiotics at different doses, Phibro has seen a species or bacterial consortium from one plant respond better to one active, while the same species or similar consortium from another customer does the opposite, she says. “We suggest customers use antimicrobials in a more informed manner.”

While plants once relied more on antimicrobials to control infections, producers increasingly have been using new tools to find infection hotspots and fine tuning their clean-in-place (CIP) protocols, Forbes says. “The shortcomings of caustic cleaning have been exposed, and plants are managing their caustic program differently or looking for an alternative.” 

The hydroxide molecule in caustic that provides cleaning action is unstable, she explains. “It can be consumed quickly in reactions and not be there for cleaning—reacting with residual mash or carbon dioxide.” While some plants compensate by adding more caustic, others are trying alternatives offered by Phibro and other venders.

Care needs to be taken in making changes, she adds. She’s seen plants that change cleaning procedures where the infection rate has gone up, while others switching to a noncaustic cleaning program will see a dramatic reduction in what had become chronic infections.

To help find infection sources, Phibro has deployed infrared technology and borescopes, Forbes says. “As plants age, things like valves, level indicators, flow indicators start to lose their integrity and you can have infections where you didn’t before.”

For example, valves on propagator or fermentation fill lines might no longer close properly, allowing small amounts of material to seep through, become stagnant and infected. “It doesn’t take much to get a major bacterial infection,” she says.  Using infrared technology to observe product flow can help producers find failing valves and places where cleaning solutions aren’t contacting all the surfaces they need to.

Borescopes can be run through lines to see whether they are being properly cleaned. If the borescope is covered in slime when it’s pulled out, biofilm is present, she adds. The borescope is also helpful in inspecting the carbon dioxide header off the fermentation tank, she says.  “If our evidence shows this is dirty, if there’s mash residue there, it’s worth the investment to get that cleaned out.”

Challenges From New Yeasts, Enzymes
The new generation of enzymes will potentially present infection challenges, Forbes continues. The new enzymes are liberating so much more from the corn kernel that the chances of having food sources for bacteria post-fermentation have increased. “You can now give bacteria a food source in the beer well, whereas 10 years ago, you didn’t,” she says.

The newer high-performance yeasts are presenting other challenges. “Some genetically modified yeasts seem very sensitive to the organic acids that are produced by bacteria, Forbes says. “Contamination is much more damaging, so plants have had to be more vigilant on infection management.”

The high-performance yeasts produce a lot more ethanol, “but it comes at a cost,” says Allen Ziegler, CEO of Archangel Inc. The company is introducing a new tool to help plants monitor bacteria. GenesisGene gives plants the ability to run rapid bacteria analysis in the ethanol lab by utilizing DNA technology to identify the type and amount of bacteria in a sample. Up to 14 samples can be run simultaneously, with primers chosen to identify specific species or to look for all organic acid-producing bacteria, Ziegler explains. Once baselines are established when the plant is running well, if organic acid levels in samples begin to rise, samples can be pulled from multiple locations in the process flow to compare and quickly determine the problem area. “This technology allows you to identify bacteria type and quantity quickly,” Ziegler says. They’ve found elevated bacteria counts in heat exchangers, ferm fill lines, the CO2 scrubber, even cook. “Some of these bacteria can be very hardy.”

Designed to test high-solids mash, Ziegler adds that customers have asked if the GenesisGene can test distillers grains. “It wasn’t developed for that, but it works,” he says. “Plants can test on-site and don’t have to wait to get the results.”

Feed Impacts
The move toward high-protein specialty feeds is another factor prompting ethanol producers to improve their antimicrobial programs. “In the past, if elevated organic acids occurred, it was difficult, time consuming and problematic to pinpoint the source,” Ziegler says. “The on-site methods can only find 1% of the bacteria and are prone to a high degree of error, which often leads to treating the symptom rather than the disease.  While there is a potential for auditing under provisions of the Food Safety Modernization Act, the goal for all facilities is to minimize the utilization of antibiotics, and GenesisGene is one tool that can help get you there.”

Long-time provider of hops-based antimicrobials BetaTec is seeing increased interest in antibiotic-free treatments, says Jason Lanham, director of sales and marketing for BetaTec North America. In the past couple of years, as ethanol plants begin to produce high-value, high-protein feeds, they are encountering a no antibiotic ever (NAE) movement working its way up the food chain. Poultry producers such as Tyson and Perdue announced, for example, that all branded chicken products are raised with NAE. “We now see ethanol plants testing and finding antibiotic residuals in coproducts,” he says, noting that antibiotic-free DDGS is 100% achievable when using hops technology.

As BetaTec reps work with producers in implementing a custom program, they see plants changing all the time, Lanham says. “Plants are constantly trying to increase yield and production efficiency. They’re trialing several technologies throughout the year—different enzymes, different cleaning agents. We can go into five of the same design plants—an ICM 50, for instance—and all five potentially use various treatment plans of our product because each may have a different process, including CIP times or even bacteria load variability.”  

Delayed Introductions
A year ago, when the COVID pandemic first hit, BetaTec introduced FermaHop Pro to respond to some of those industry changes. The company’s innovation team, based in the UK, had developed a new proprietary blend of hops extract that maintains high antimicrobial activity levels in a broad pH range. “Shortly after we introduced our new product, people stopped traveling and the ethanol industry experienced a dip in production due to the pandemic,” Lanham says. “We instantly saw a halt in all new product trials.” As the industry started to adapt to the new norm, BetaTec relaunched FermaHop Pro.

Similarly, Phibro had completed demonstration trials on a new automation technology, trademarked PhibroMat, when the pandemic put the full rollout in slow gear, Forbes says. For years, antibiotic addition has been done manually, but plants are increasingly keen on automation. The new system vends the powdered product into liquid and injects that into process lines. “There are advantages to the plant, more than just the hands-free addition,” she explains. It helps with traceability and inventory management, plus provides a secured storage space for the antimicrobial.

Archangel’s roll out of its GenesisGene was impacted by the pandemic as well, Ziegler says. “The guts of the box is the same as what they use for COVID-19 testing,” he says, which resulted in his equipment orders being diverted to the pandemic response. On the positive side, the efforts to streamline the DNA testing protocols meant a time-consuming centrifuge step was replaced with a simpler, quicker sample separation method.

All three company representatives report that producers know from experience that longer hold times and slower product flows increase the potential for infections. So, while responding to the pandemic with slower run rates, bad infections were rare as producers also increased their CIP cycles and upped their antimicrobial regimes.

Author: Susanne Retka Schill
Freelance Journalist