Inverse metabolic engineering of Bacillus subtilis for xylose utilization based on adaptive evolution and whole-genome sequencing.

Efficient utilization of xylose by bacteria is essential for production of fuels and chemicals from lignocellulosic biomass. In this study, Bacillus subtilis 168 was subjected to laboratory adaptive evolution, and a mutant E72, which could grow on xylose with a maximum specific growth rate of 0.445 h(-1), was obtained. By whole-genome sequencing, 16 mutations were identified in strain E72. Through further analysis, three of them, which were in the coding regions of genes araR, sinR, and comP, were identified as the beneficial mutations. The reconstructed strain 168ARSRCP harboring these three mutations exhibited similar growth capacity on xylose to the evolved strain E72, and the average xylose consumption rate of this strain is 0.530 g/l/h, much higher than that of E72 (0.392 g/l/h). Furthermore, genes acoA and bdhA were deleted and the final strain could utilize xylose to produce acetoin at 71 % of the maximum theoretical yield. These results suggested that this strain could be used as a potential platform for production of fuels and chemicals from lignocellulosic biomass.