Resolving bacterial contamination of fuel ethanol fermentations with beneficial bacteria – an alternative to antibiotic treatment

Authors: Rich, Joseph; Bischoff, Kenneth; Leathers, Timothy; Anderson, Amber; Liu, Siqing; Skory, Christopher - Chris

Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2017
Publication Date: 9/14/2017
Publication URL: http://handle.nal.usda.gov/10113/5818830
Citation: Rich, J.O., Bischoff, K.M., Leathers, T.D., Anderson, A.M., Liu, S., Skory, C.D. 2017. Resolving bacterial contamination of fuel ethanol fermentations with beneficial bacteria – an alternative to antibiotic treatment. Bioresource Technology. 247:357-362. https://doi.org/10.1016/j.biortech.2017.09.067.
DOI: https://doi.org/10.1016/j.biortech.2017.09.067

Interpretive Summary: The chronic bacterial infection of fuel ethanol fermentations is believed to decrease yield and increase operational costs due to more frequent cleaning and the use of antibiotic treatments. Frequently these infections lead to "stuck" fermentations that requires even more extensive cleaning during plant shutdowns. While certain bacteria have been shown to lower ethanol production in yeast, possibly related to their production of acetic acid, we demonstrate herein the ability of other related bacteria to reverse the negative impact of bacterial infections. Interestingly, certain strains of a given bacteria are able to completely negate the negative impacts. Such a probiotic approach to controlling infections in industrial fermentations could minimize or eliminate the use of antibiotics and this will benefit ethanol manufacturers, as well as livestock producers and consumers.

Technical Abstract: Fuel ethanol fermentations are not performed under aseptic conditions and microbial contamination reduces yields and can lead to costly “stuck fermentations.” Antibiotics are commonly used to combat contaminants, but these may persist in the distillers grains co-product. Among contaminants, it is known that certain strains of lactic acid bacteria are capable of causing stuck fermentations, while other strains appear to be harmless. However, it was not previously known whether or how these strains interact one with another. In this study, more than 500 harmless strains of lactic acid bacteria were tested in a model system in combination with strains that cause stuck fermentations. Among these harmless strains, a group of beneficial strains was identified that restored ethanol production to near normal levels. Such beneficial strains may serve as an alternative approach to the use of antibiotics in fuel ethanol production.