Identification of lignocellulosic derivatives inhibiting succinic acid fermentation and molecular mechanism investigation

Phenolic derivatives from lignocellulosic biomass under harsh pretreatment conditions may inhibit microorganisms. Waste liquid produced from alkali pretreatment of sugarcane bagasse (SCB) was qualitatively and quantitatively analyzed. Model compounds were used to evaluate the effects of major derivatives of alkali pretreatment liquid (APL) on the growth and succinic acid (SA) synthesis of Actinobacillus succinogenes ATCC 55618, and molecular mechanisms were analyzed with transcriptome and proteome sequencing. The 10 most abundant measured components in APL were all lignin degradation products, and they showed different degrees of inhibitory effects on A. succinogenes. Benzoic acid and p-hydroxy benzaldehyde exhibited most serious inhibition to A. succinogenes, causing biomass and SA concentration to decrease by over 30 % and 45 %, respectively. This could be attributed to the presence of inhibitors caused the down-regulation of genes including phosphofructokinase, xylulose kinase, pyruvate carboxylase, and acetate kinase, which are crucial in pathways for sugar uptake, CO₂ fixation, and reducing power supply.