Biofilms can form anywhere, but can be scrubbed out

By Tim Albrecht | June 13, 2018

Biofilms have gained attention recently across the ethanol industry. They really have an impact on all industries, Wayne Mattsfield, staff scientist for Phibro Ethanol Performance Group, said during the panel, “The Ongoing Effort to Curtail the Impact of Bacterial Infection and Biofilms at Ethanol Plants,” at the Fuel Ethanol Workshop & Expo in Omaha.

Joining Mattsfield on the panel were Andrew Ledlie, North America marketing manager for Solenis LLC, Stephanie Gleason, technical service leader for DuPont Industrial Biosciences, and Carlie LaTourell, technical services manager for Lallemand Biofuels & Distilled Spirits.

The panel discussed what biofilms are and how to eliminate them, microbial metabolites and bacterial contamination in ethanol plants.

The formation of biofilm is a very simple process and can occur rather quickly, Ledlie said. “As soon as anything gets on a surface that roughs it up or creates a deposit, biofilm and bacteria has an area to attach to. Biofilm can form in just one week on a system.”

It's very easy for biofilm, even a very small amount, to create plenty of problems, Ledlie added. “The glue on scotch tape is 20 microns thick, that amount of biofilm can reduce heat transfer in your heat exchanger by more than 5 percent.”

There are three types of bacteria, including sensitive, persistent and resistant. The gray area in the middle is persistence, Mattsfield said. “Persistence is a case where some bacteria may not be affected by initial treatment but that doesn’t mean they aren’t sensitive to the antimicrobial.”

Persister bacteria aren’t formed in response to the pressure of antimicrobial treatment, they don’t really do anything usually but are always around. Their job is to repopulate if the bacteria run into a problem, Mattsfield said. “They are the ones that are just always kind of there.”

Gleason shifted gears a bit midway through the panel to discuss metabolites and the impact they can have on your facility. Metabolites are often small molecules that are formed during or as a result of metabolism. In fermentation the primary source of all these compounds present is the ethanol producing yeast, but other bacteria can influence the “diversity of what compounds are present in the mash,” Gleason said.

Often when metabolites are present at high levels they can cause a stress response in yeast. Stress results in lower titers, lower yields, slower kinetics, and so on, Gleason said. Ultimately it affects a producers revenues.”

“The sooner you realize you have a problem the quicker you can resolve the problem. Through quick identification of ‘bad’ metabolites and taking corrective action the impact of their presence can be limited or mitigated all together. Consistent, standardized practices throughout the plant will go a long way to controlling the ‘bad’ metabolites. Routine hygiene audits to assess if measures are working will help as well,” Gleason said.

Gleason used a common sports phrase to convey safe guarding against metabolites saying, “Sometimes the best offense is a good defense.”