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

Abstract

Second generation (2G) ethanol is produced through the use of lignocellulosic biomass. However, the pretreatment processes generates 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 challenge 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 an effective detoxification kinetics when compared to the homofermentative LAB. This knowledge is important because LAB can be explored both within the scope of bio-detoxification, being applied before the fermentation. Key points- Heterofermentative LAB presented the ability to decrease the concentrations of furfural and HMF - LAB can be used in the bio-detoxification to remove the inhibitors before fermentations - The presence of furan derivatives had a growth stimulus observed in heterofermentative LAB