Curcumin production by engineered Escherichia coli biofilms

In recent years, microbial biofilms have emerged as a new generation of biocatalysts due to their potential for the production of value-added compounds such as recombinant proteins. The production of the recombinant protein curcumin using an artificial pathway in Escherichia coli was first described by Katsuyama et al., and subsequent studies have been performed to evaluate the potential of this pathway in suspended cell cultures. A curcumin concentration of 563 mg/mL was achieved using ferulic acid. Curcumin has been used as an antioxidant, flavoring agent and natural colorant in various food products. This work aimed to evaluate the impact of temperature and induction conditions on biofilm development and curcumin production by E. coli JM109(DE3) cells harbouring the At4CL_DCS_CURS plasmid for the artificial synthesis of curcumin.

The biofilm assay was performed in 12-well plates with PVC surfaces for 7 days at different temperatures (30 ºC and 26 ºC), with and without induction with isopropyl β-d-1-thiogalactopyranoside (IPTG) and ferulic acid. Biofilm and planktonic states were monitored by the number of culturable cells in Colony-Forming Units (CFUs) and curcumin production by High-Performance Liquid Chromatography (HPLC). The biofilm structure was also assessed using Optical Coherence Tomography (OCT).

The results showed that the addition of IPTG and ferulic acid negatively affected the viability of planktonic and biofilm cells. Nevertheless, the curcumin production was about 12-fold higher in biofilms cells than in planktonic cells under the tested conditions. These preliminary data may be a promising indication that biofilms can be a good platform for the production of recombinant proteins and other value-added compounds.