Investigating the ability of Rhodosporidium toruloides-1588 to use furfural as a carbon source and its degradation: an enzyme identification study

Abstract

Lignocellulosic biomass has been regarded as a sustainable feedstock for the biorefinery industry. In general, pretreatment and saccharification are required to breakdown the complex link between lignin, cellulose and hemicellulose, thus releasing the fermentable sugars such as glucose, xylose or arabinose. However, microbial growth inhibitors such as furans, phenolic compounds and organic acids are also produced during the pretreatment of lignocellulosic biomass. Among all, furfural is specifically notorious for negatively affecting microbial growth and their product accumulation ability. In this sense, the present study aims to identify the ability of Rhodosporidium toruloides-1588 to use furfural as a carbon source and to accumulate lipids and carotenoids. R. toruloides-1588 was able to grow in 2 g L⁻¹ of furfural and degrade it into non-toxic products. Upon proteomic evaluation of R. toruloides-1588, furfural degrading enzymes such as alcohol dehydrogenase and aldehyde dehydrogenase were identified to be responsible for furfural degradation into furfuryl alcohol and 2-furoic acid. The maximum furfural degradation rate was observed to be 25 mg L⁻¹ h⁻¹ in minimal media containing glucose and furfural, while it was 15 mg L⁻¹ h⁻¹ in minimal media containing furfural. Additionally, the role of carotenoid accumulation and its impact during furfural exposure have been identified. The study shows the capacity of R. toruloides–1588 to use furfural as an energy source and the presence of potential furfural degrading enzymes. This research paves the way for in situ detoxification of hydrolysates as a major step towards the efficient utilization of lignocellulosic biomass and decreasing the biofuel production cost.