AUTHOR=Xiao Kang , Yue Xiu-Hong , Chen Wen-Chao , Zhou Xue-Rong , Wang Lian , Xu Lin , Huang Feng-Hong , Wan Xia 

TITLE=Metabolic Engineering for Enhanced Medium Chain Omega Hydroxy Fatty Acid Production in Escherichia coli

JOURNAL=Frontiers in Microbiology

VOLUME=9

YEAR=2018

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2018.00139

DOI=10.3389/fmicb.2018.00139

ISSN=1664-302X

ABSTRACT=<p>Medium chain hydroxy fatty acids (HFAs) at ω-1, 2, or 3 positions (ω-1/2/3) are rare in nature but are attractive due to their potential applications in industry. They can be metabolically engineered in <italic>Escherichia coli</italic>, however, the current yield is low. In this study, metabolic engineering with P450<sub>BM3</sub> monooxygenase was applied to regulate both the chain length and sub-terminal position of HFA products in <italic>E. coli</italic>, leading to increased yield. Five acyl-acyl carrier protein thioesterases from plants and bacteria were first evaluated for regulating the chain length of fatty acids. Co-expression of the selected thioesterase gene <italic>CcFatB1</italic> with a fatty acid metabolism regulator <italic>fadR</italic> and monooxygenase <italic>P450</italic><sub><italic>BM</italic>3</sub> boosted the production of HFAs especially ω-3-OH-C14:1, in both the wild type and <italic>fadD</italic> deficient strain. Supplementing renewable glycerol to reduce the usage of glucose as a carbon source further increased the HFAs production to 144 mg/L, representing the highest titer of such HFAs obtained in <italic>E. coli</italic> under the comparable conditions. This study illustrated an improved metabolic strategy for medium chain ω-1/2/3 HFAs production in <italic>E. coli</italic>. In addition, the produced HFAs were mostly secreted into culture media, which eased its recovery.</p>