Pre-treatment step with Leuconostoc mesenteroides or L. pseudomesenteroides strains removes furfural from Zymomonas mobilis ethanolic fermentation broth

Authors: Hunter, William; Manter, Daniel

Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/26/2014
Publication Date: 7/3/2014
Publication URL: http://DOI:10/1016/j.biortech.2014.06.097
Citation: Hunter, W.J., Manter, D.K. 2014. Pre-treatment step with Leuconostoc mesenteroides or L. pseudomesenteroides strains removes furfural from Zymomonas mobilis ethanolic fermentation broth. Bioresource Technology. 169:162-168. DOI:10/1016/j.biortech.2014.06.097..

Interpretive Summary: Dilute acid hydrolysis is a common and necessary early step in the processing of biomass that is to be converted to ethanol for fuel. During this process furfural forms. This is bad as it is a known inhibitor of growth and ethanol production by the bacteria Zymomonas mobilis. The present study investigated the use of a biological pre-treatment to reduce that amount of furfural present in biofuel fermentation broths. The pre-treatment involved inoculating and incubating the fermentation broth with strains of the bacteria Leuconostoc mesenteroides or L. pseudomesenteroides prior to the ethanolic fermentation with Z. mobilis. Three Leuconostoc strains were investigated and found to lower the toxicity of furfural by converting it to furfuryl alcohol. Coupling this biological pre-treatment to a Z. mobilis ethanolic fermentation was found to reduce the amount of furfural present in the fermentation broth and to improve the growth of Z. mobilis, and to increase dextrose uptake and ethanol formation by these bacteria. The use of the pre-treatment and the presence of the Leuconostoc strains in the fermentation broth did not interfere with the Z. mobilis ethanolic fermentation process or reduce the amounts of ethanol produced. The method suggests a possible technique for reducing the effect that furfural has on the production of ethanol for use as a biofuel.

Technical Abstract: Furfural (furan-2-carboxaldehyde), formed during dilute acid hydrolysis of biomass, is an inhibitor of growth and ethanol production by Zymomonas mobilis. The present study used a biological pre-treatment to reduce that amount of furfural in a model biofuel fermentation broth. The pre-treatment involved inoculating and incubating the fermentation broth with strains of Leuconostoc mesenteroides or L. pseudomesenteroides prior to the ethanolic fermentation with Z. mobilis. Three Leuconostoc strains, isolated from environmental samples on agar plates containing furfural, grew in the presence of up to 4.5 g L-1 furfural and lowered its toxicity by converting it to furfuryl alcohol. Coupling this biological pre-treatment to a Z. mobilis ethanolic fermentation reduced furfural in the fermentation broth, improving Z. mobilis growth, dextrose uptake and ethanol formation. The pre-treatment also permitted the formation of ethanol in the presence of amounts of furfural, 5.2 g L-1, that otherwise inhibited ethanol formation. The use of the pre-treatment and the presence of the Leuconostoc strains in the fermentation broth did not interfere with the Z. mobilis ethanolic fermentation or the amounts of ethanol produced. The method suggests a possible technique for reducing the effect that furfural has on the production of ethanol for use as a biofuel.