초록
<P><B>Background</B></P><P>1,3-Propanediol (1,3-PDO) is important building blocks for the bio-based chemical industry, <I>Klebsiella pneumoniae</I> can be an attractive candidate for their production. However, 1,3-PDO production is high but productivity is generally low by <I>K. pneumoniae</I>. In this study, repeated fed-batch cultivation by a lactate and 2,3-butanediol (2,3-BDO) deficient mutant of <I>K. pneumoniae</I> were investigated for efficient 1,3-PDO production from industrial by-products such as crude glycerol.</P><P><B>Results</B></P><P>First, optimal conditions for repeated fed-batch fermentation of a Δ<I>ldhA</I> mutant defective for lactate formation due to deletion of the lactate dehydrogenase gene (<I>ldhA</I>) were determined. Maximal 1,3-PDO production level and productivity obtained by repeated fed-batch fermentation under optimized conditions were 81.1 g/L and 3.38 g/L/h, respectively, and these values were successfully maintained for five cycles of fermentation without any loss of fermentation capacity. This results were much higher than that of the normal fed-batch fermentation. The levels of 2,3-BDO, which is a major by-product, reaching up to ~ 50% of the level of 1,3-PDO, were reduced using a mutant strain [Δ(<I>ldhA als</I>)] containing an additional mutation in the biosynthetic pathway of 2,3-BDO (deletion of the acetolactate synthase gene). The levels of 2,3-BDO were reduced to about 20% of 1,3-PDO levels by repeated fed-batch fermentation of Δ(<I>ldhA als</I>), although maximal 1,3-PDO production and productivity also decreased owing to a defect in the growth of the 2,3-BDO-defective mutant strain.</P><P><B>Conclusion</B></P><P>This repeated fed-batch fermentation may be useful for reducing the cost of 1,3-PDO production and may be promising industrialization prospect for the 1,3-PDO production.</P>