Inhibitory effects of lignocellulose pretreatment degradation products (hydroxymethylfurfural and furfural) on succinic acid producing Actinobacillus succinogenes

Pretreatment is crucial step to overcome the stiffness of lignocellulosic materials so as to make sugars available for subsequent enzymatic hydrolysis and microbial fermentation. Unfortunately, commonly used pretreatment methods cause formation of various toxic degradation products that have inhibitory effect on growth and fermentation. Hydroxymethylfurfural (HMF) and furfural are furan derivative inhibitors generated via degradation of hexoses and pentoses, respectively. In this study, inhibitory effects of HMF and furfural (0-10 g/L) on succinic acid producing Actinobacillus succinogenes were investigated using lignocellulosic model sugars of glucose and xylose. To this end, A. succinogenes attained explicable level of tolerance against these inhibitors but better performance with HMF than furfural. Nevertheless, synergetic effect of these inhibitors was severer compared with individual one. Overall, this study could provide vital notions to understand strain's tolerance level, and thereby helps to apply efficient pretreatment methods, utilize appropriate substrates, and develop robust biocatalysts.