초록
<P>Glucose, xylose and arabinose are the three most abundant monosaccharide found in lignocellulosic biomass. Effectively and simultaneously utilization of these sugars by microorganisms for production of the biofuels and bio-chemicals is essential toward directly fermentation of the lignocellulosic biomass. In our previous study, the recombinant <I>Bacillus subtilis</I> 168ARSRCPΔ<I>acoA</I>Δ<I>bdhA</I> strain was already shown to efficiently utilize xylose for production of acetoin, with a yield of 0.36 g/g xylose. In the current study, the <I>Bacillus subtilis</I>168ARSRCPΔ<I>acoA</I>Δ<I>bdhA</I> strain was further engineered to produce acetoin from a glucose, xylose, and arabinose mixtures. To accomplish this, the endogenous xylose transport protein AraE, the exogenous xylose isomerase gene <I>xylA</I> and the xylulokinase gene <I>xylB</I> from <I>E</I>. <I>coli</I> were co-overexpressed in the <I>Bacillus subtilis</I> 168ARSRCPΔ<I>acoA</I>Δ<I>bdhA</I> strain, which enabled the resulting strain, denoted ZB02, to simultaneously utilize glucose and xylose. Unexpectedly, the ZB02 strain could simultaneously utilize glucose and arabinose also. Further results indicated that the transcriptional inhibition of the arabinose transport protein gene <I>araE</I> was the main limiting factor for arabinose utilization in the presence of glucose. Additionally, the arabinose operon in <I>B</I>. <I>subtilis</I> could be activated by the addition of arabinose, even in the presence of glucose. Through fed-batch fermentation, strain ZB02 could simultaneously utilize glucose, xylose, and arabinose, with an average sugar consumption rate of 3.00 g/l/h and an average production of 62.2 g/l acetoin at a rate of 0.864 g/l/h. Finally, the strain produced 11.2 g/l acetoin from lignocellulosic hydrolysate (containing 20.6g/l glucose, 12.1 g/l xylose and 0.45 g/l arabinose) in flask cultivation, with an acetoin yield of 0.34 g/g total sugar. The result demonstrates that this strain has good potential for the utilization of lignocellulosic hydrolysate for production of acetoin.</P>