초록
<P><B>ABSTRACT</B></P><P>Free fatty acids (FFAs) can be used as precursors for the production of biofuels or chemicals. Different composition of FFAs will be useful for further modification of the biofuel/biochemical quality. Microbial biosynthesis of even chain FFAs can be achieved by introducing an acyl‐acyl carrier protein thioesterase gene into <I>E</I>. <I>coli</I>. In this study, odd straight medium chain FFAs production was investigated by using metabolic engineered <I>E</I>. <I>coli</I> carrying acyl‐ACP thioesterase (TE, <I>Ricinus communis</I>), propionyl‐CoA synthase (<I>Salmonella enterica</I>), and β‐ketoacyl‐acyl carrier protein synthase III (four different sources) with supplement of extracellular propionate. By using these metabolically engineered <I>E. coli</I>, significant quantity of C13 and C15 odd straight‐chain FFAs could be produced from glucose and propionate. The highest concentration of total odd straight chain FFAs attained was 1205 mg/L by the strain HWK201 (pXZ18, pBHE2), and 85% of the odd straight chain FFAs was C15. However, the highest percentage of odd straight chain FFAs was achieved by the strain HWK201 (pXZ18, pBHE3) of 83.2% at 48 h. This strategy was also applied successfully in strains carrying different TE, such as the medium length acyl‐ACP thioesterase gene from <I>Umbellularia californica</I>. C11 and C13 became the major odd straight‐chain FFAs. Biotechnol. Bioeng. 2014;111: 2209–2219. © 2014 Wiley Periodicals, Inc.</P>