Homo-and heterofermentative lactobacilli are differently affected by lignocellulosic inhibitory compounds

Abstract

Second generation (2G) ethanol is produced using lignocellulosic biomass. However, the pre-treatment processes generate a variety of molecules (furan derivatives, phenolic compounds, and organic acids) that act as inhibitors of microbial metabolism, and thus reduce the efficiency of the fermentation step in this process. In this context, the present study aimed to investigate the effect of furan derivatives on the physiology of lactic acid bacteria (LAB) strains that are potential contaminants of ethanol production. Homofermentative and heterofermentative strains of laboratory LAB and isolated from first generation ethanol fermentation were used. LAB strains were challenged to grow in the presence of furfural and hydroxymethyylfurfural (HMF). We found that the effect of HMF and furfural on the growth rate of LAB is dependent of the metabolic type, and growth kinetics in the presence of these compounds is enhanced for heterofermentative LAB, whereas is inhibitory to homofermentative LAB. Sugar consumption and product formation were also enhanced in the presence of furaldehydes in heterofermentative LAB, that displayed effective detoxification kinetics when compared to the homofermentative LAB. This knowledge is important because lactic acid bacteria can be explored within the scope of bio-detoxification, as well as to guide metabolic engineering strategies to yeast biocatalysts based on the mechanisms used by these bacteria.