초록
<P><B>Background</B></P><P><I>Bacillus amyloliquefaciens</I> B10-127 exhibited an excellent ability for industrial-scale microbial fermentation of 2,3-butanediol (2,3-BD) from biodiesel-derived glycerol. However, the accumulation of by-products (acetoin, acetoin, lactate and succinate) and the 2,3-BD yield remains prohibitively low for commercial production.</P><P><B>Results</B></P><P>Several strategies were developed to manipulate the carbon flux to 2,3-BD branch in a designed <I>B. amyloliquefaciens</I>. Firstly, extra copies of NADH/NAD<SUP>+</SUP> regeneration system were introduced into <I>B. amyloliquefaciens</I> by co-overproduction of glycerol dehydrogenase and acetoin reductase, which resulting in improvement of 2,3-BD production and suppression of by-products accumulation. Subsequently, the transcriptional regulator ALsR under the control of a moderate promoter P<SUB>bdhA</SUB> was introduced into <I>B. amyloliquefaciens</I>, which increased carbon flux to 2,3-BD branch. Finally, a three-stage dissolved oxygen control strategy were proposed based on analysis of the characteristic of 2,3-BD fermentation, and a two-stage pH control strategy were proposed based on different pH preferences of ACR for reduction and oxidation. Following these strategies, a high titer (102.3 g/L), yield (0.44 g/g), and productivity (1.16 g/L/h) of 2,3-BD were achieved.</P><P><B>Conclusions</B></P><P>To our knowledge, this is the highest reported 2,3-BD production using biodiesel-derived glycerol as substrate, and this designed <I>B. amyloliquefaciens</I> should be an excellent candidate for producing 2,3-BD on an industrial scale.</P>