Triacylglycerol production from corn stover using a xylose-fermenting Rhodococcus opacus strain for lignocellulosic biofuels

Abstract

Triacylglycerols (TAGs) are in the spotlight as a feasible source of hydrocarbon-based biofuels. Rhodococcus opacus PD630 produces large amounts of intracellular TAGs in cultivations containing high concentrations of glucose, but it does not utilize xylose present in all hydrolysates of lignocellulosic biomass. We constructed a highpotency xylose-fermenting R. opacus strain MITXM-61 that exhibited robust growth and TAG biosynthesis on high concentrations of xylose by activating potential xylose-metabolism genes. MITXM-61 had the uncommon capacity to grow in defined media supplemented with xylose at concentrations of greater than 200 gl-1. MITXM-61 grown in corn stover hydrolysates containing 118 gl-1 of initial total sugars was capable of completely and simultaneously utilizing both xylose and glucose in the genuine lignocellulosic feedstock, and yielded 15.9 gl-1 of TAGs, corresponding to 54% of the cell dry weight. The oleaginous bacterium R. opacus strain proved useful for developing a new manufacturing paradigm to generate advanced lignocellulosic biofuels.