Propionate is used as an important preservative and important chemical
intermediate for the synthesis of cellulose fibers,
herbicides, perfumes, and
pharmaceuticals. Biosynthetic propionate has mainly been produced by
Propionibacterium, which has various limitations for industrial application.
Jing Li led a group of scientists from the Chinese Academy of Sciences and
engineered Escherichia coli, combining a reduced TCA cycle with the native
sleeping beauty mutase (Sbm) cycle to construct a fermentation pathway for
anaerobic propionate production. The team overexpressed the Sbm operon in E.
coli MG1655, yielding 0.24 g/L of propionate.
Genetic modification was also done to convert mixed fermentation products to
succinate to increase precursors, thus, slightly increasing yield. Different
types of promoters were also evaluated to maximize the Sbm operon. The
constitutive promoter Pbba led to the highest titer of 2.34 g/L.
Methylmalonyl CoA mutase from Methylobacterium extorquens AM1 was also added
to strain T110 (pbba-Sbm) to enhance this process.
This study lays the groundwork for industrial propionate production using E.
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