Synthetic biology approach for the design of butyrate producing bacteria for colon cancer therapy

Kızıl, Cihat Burak
Butyric acid is a short chain fatty acid (SCFA) that is generated in the colon by butyrate-producing bacteria. Butyrate, along with other SCFAs, serve as substrates for energy production in the gut epithelium. Additionally, these compounds are known to reduce inflammation and enhance differentiation of mammalian cells. Several species of bacteria are known to produce butyrate in the gut through different biochemical pathways. In this study we have aimed to generate a butyrate producing commensal E. coli K12 strain that is known to be non butyrogenic. For this, we have used a strain in which fermentation related pathways have been deleted (ΔadhE, Δldha, ΔackA-pta, ΔfrdC) while enzymes for the reversal of β-oxidation (AtoB, FadB, FabI) and butyrate production [Butyryl-CoA: Acetate-CoA transferase (ButCoAT)] have been overexpressed. The E. coli K12 strain engineered with these alterations was capable of synthesizing mM amounts of butyrate. Caco-2 colon cancer cell line was incubated with a 1:1(v/v) mixture of conditioned medium generated from the engineered E. coli K12 strain and culture medium. A strong activation of the Mitogen Activated Protein Kinase (MAPK) family protein p38 and its downstream target MAPKAPK2 (MK2) was observed in cells treated with the conditioned medium compared to controls. The MAPK pathway orchestrates several regulatory mechanisms in epithelial cells. Our study suggests that engineered bacteria can be used to regulate gene expression in the gut.
Citation Formats
C. B. Kızıl, “Synthetic biology approach for the design of butyrate producing bacteria for colon cancer therapy,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Biology., Middle East Technical University, 2019.