• Poster No.: 2S-Ba03
  • Presentation Time: September 10, 2014　10:05-
  • Title: Enzymatic CO2 conversion to formic acid
  • Author(s): HyoJin Hwang, ○Yong Hwan Kim (Dept. Chem. Eng., Kwangwoon Univ. Seoul, Korea)

Abstract

The fixation of CO2 is one of the most important approaches to prevent global warming. The enzymatic reduction of CO2 using formate dehydrogenase (FDH) has been widely studied to produce valuable chemicals such as formic acid and methanol. Formic acid is considered a promising replacement for methanol in miniature fuel cells. Formic acid can be produced by the hydrolysis of methyl formate, which is synthesized via methanol carbonylation in commercial processes. Therefore, it would be very attractive to prepare formic acid by the direct enzymatic reduction of CO2.
In contrast to plenty of chemical CO2-reducing catalysts, there are few biocatalysts used in direct CO2; currently, the only biocatalysts are Nicotinamide adenine dinucleotide (NAD)-independent or NAD-dependent FDHs. NAD-independent FDHs have high CO2 reduction activity but include extremely oxygen-sensitive catalytic components such as metal ions (tungsten or molybdenum), iron-sulfur clusters, and selenocysteine, making these FDHs unsuitable for industrial applications. Recently, NAD-dependent FDHs were utilized in a CO2 reduction system as an alternative to NAD-independent FDHs. Although the commercially available Candida boidinii formate dehydrogenase (CbFDH) has been widely adopted for the regeneration of NADH in enzyme-coupled reaction systems, it is also employed as a CO2-reducing biocatalyst in electrochemical and enzymatic reactions. Unfortunately, the CO2 reduction activity of CbFDH is too low to allow efficient CO2 conversion, which leads us to search for alternatives.
In this presentation, two kinds approach will be discussed using efficient NADH dependent formate dehydrogenase as well as NADH independent/O2 resistant formate dehydrogenase to produce formate from CO2. Since newly discovered NADH independent formate dehydrogenase showed much excellent CO2 reduction activity using electrons supplied from cathode, it is anticipated to play a pivotal role in the scale-up of bioelectrochemical production of formate.