BioChem - DOS

Engineering of Ralstonia eutropha H16 for autotrophic and heterotrophic production of methyl ketones

Applied and environmental microbiology

Mü ller, Jana; MacEachran, Daniel; Burd, Helcio; Sathitsuksanoh, Noppadon; Bi, Changhao; Yeh, Yi-Chun; Lee, Taek Soon; Hillson, Nathan J.; Chhabra, Swapnil R.; Singer, Steven W.; Beller, Harry R.

<P><I>Ralstonia eutropha</I> is a facultatively chemolithoautotrophic bacterium able to grow with organic substrates or H<SUB>2</SUB> and CO<SUB>2</SUB> under aerobic conditions. Under conditions of nutrient imbalance, <I>R. eutropha</I> produces copious amounts of poly[(<I>R</I>)-3-hydroxybutyrate] (PHB). Its ability to utilize CO<SUB>2</SUB> as a sole carbon source renders it an interesting new candidate host for the production of renewable liquid transportation fuels. We engineered <I>R. eutropha</I> for the production of fatty acid-derived, diesel-range methyl ketones. Modifications engineered in <I>R. eutropha</I> included overexpression of a cytoplasmic version of the TesA thioesterase, which led to a substantial (&#x003E;150-fold) increase in fatty acid titer under certain conditions. In addition, deletion of two putative &#x03B2;-oxidation operons and heterologous expression of three genes (the acyl coenzyme A oxidase gene from <I>Micrococcus luteus</I> and <I>fadB</I> and <I>fadM</I> from <I>Escherichia coli</I>) led to the production of 50 to 65 mg/liter of diesel-range methyl ketones under heterotrophic growth conditions and 50 to 180 mg/liter under chemolithoautotrophic growth conditions (with CO<SUB>2</SUB> and H<SUB>2</SUB> as the sole carbon source and electron donor, respectively). Induction of the methyl ketone pathway diverted substantial carbon flux away from PHB biosynthesis and appeared to enhance carbon flux through the pathway for biosynthesis of fatty acids, which are the precursors of methyl ketones.</P>

2013

American Society for Microbiology

0099-2240

1098-5336

79

14

pp.4433-4439

10.1128/aem.00973-13

http://click.ndsl.kr/servlet/OpenAPIDetailView?keyValue=05787966&target=NART&cn=NART70836885

https://aem.asm.org/content/aem/79/14/4433.full.pdf