(485v) Toward A Chemical Revolution: Solving Biocatalyst Inhibition for the Production of Fatty Acids

Cracking
crude oil into light olefins gave birth to chemical industry in the
early 1900s. Olefins were used to synthesize a variety of chemical
compounds that were marketed for specific applications. The
combination of depleting petroleum reserves and unstable crude oil
market prices gives rise to the need for a sustainable raw base for
the chemical industry. Short Chain Fatty Acids (SCFAs) produced in
high titer by biocatalysts are great candidates as a biorenewable
feedstock for the chemical industry. Small organic molecules produced
by biocatalysts can be defunctionalized by traditional chemical
catalysis to synthesize a plethora of precursor molecules used in the
chemical industry. SCFAs are intermediate metabolites that are used
within the cell as substrates for producing longer chain fatty acids
for membrane components. Unfortunately, SCFAs are inhibitory to cell
growth, thereby the production of SCFAs via biocatalyst is difficult.
In this work, the minimum inhibitor concentration (MIC) under
anaerobic conditions for hexanoic (C6), octanoic (C8), and decanoic
acids (C10) are determined to be 2.5 mM, 5 mM, and 10 mM
respectively. The MIC under aerobic condtions are 5mM, 10mM, and 20mM
for C6, C8, and C10 respectively. The base Escherichia coli
biocatalyst used, MG1655, is comparable to other industrial strains
8739 and 9637. Under aerobic conditions, the cells are able to
metabolize the SCFAs in the growth medium. Deletion mutants
MG1655â??fadAB, MG1655â??fadIJ, MG1655â??fadABIJ
show that the genes encoding the fatty acid degradation pathway aid
cell growth under aerobic conditions. The deletion mutant MG1655â??fadR
shows that the gene fadR inhibits the fatty acid degradation
pathway leading to cell growth inhibition.