Invited Talk 21st International Conference on Biological Inorganic Chemistry 2025

Visible-light driven production of biodegradable plastic precursor from gaseous CO2 with photo/bio-hybrid catalytic system (121663)

Yutaka Amao 1
  1. Osaka Metropolitan University, Osaka, Japan

While various plastics are inexpensive, lightweight, durable, and ductile multifunctional materials, the issue of environmental pollution caused by plastic waste has recently come under close scrutiny.  Substituting biodegradable plastics is attracting attention as a means of solving serious environmental problems such as marine floating plastic debris. Biodegradable plastics are usually manufactured from petrochemicals, which are renewable raw materials that are eventually broken down by living organisms into water and CO2.  Among these biodegradable plastics, poly-3-hydroxybutyrate (PHB)-based plastics are an attractive alternative to conventional plastics because these are compostable, made from renewable raw materials, and biodegradable.  A new biodegradable plastics precursor production from gaseous CO2 using visible-light driven catalytic system consisting of triethanol amine (TEOA), zinc porphyrin (ZnP), [Cp*Rh(bpy)(H2O)]2+ (Cp*: 1,2,3,4,5-pentamethylcyclopentadien, bpy: 2,2’-bipyridine), NAD+ and biocatalysts is a candidate for a useful green process method. 

In this lecture, an enzyme extract containing acetone carboxylase (AC) and 3-hydroxybutyrate dehydrogenase (HBDH) from a purple nonsulfur photosynthetic bacterium was applied as the biocatalysts for the visible light-driven 3-hydroxybutyrate production from acetone and gaseous CO2 system consisting of TEOA, zinc tetraphenylporphyrin tetrasulfonate (ZnTPPS) ,[Cp*Rh(bpy)(H2O)]2+ and NAD+ was introduced as an example for a PHB-based plastic precursor production with the photo/bio-hybrid catalytic system [1-4].

When the sample solution containing acetone (0.5 mM), TEOA (0.2 M), ZnTPPS (50 μM), [Cp*Rh(bpy)(H2O)]2+ (5.0 μM), NAD+ (2.0 mM), ATP (2.0 mM), MgCl2 (2.0 mM) and enzyme extract (AC and HBDH) in HEPES-NaOH buffer with CO2 gas was irradiated with a halogen lamp for 7 h, ca.0.4 mM of 3-hydroxybutyrate was produced and yield for acetone to 3-hydroxybutyrate was estimated to be ca.80%. Thus, the producing visible light-driven 3-hydroxybutyrate using CO2 gas and acetone as raw materials is succeeded.

This work was partially supported by Grant-in-Aid for Specially promoted Research (23H05404), Scientific Research (B) (22H01872), (22H01871) and by Institute for Fermentation, Osaka (IFO) (G-2023-3-050).

  1. Y. Kita and Y. Amao, Chem. Commun., 2022, 58, 11131.
  2. Y. Kita, R. Fujii and Y. Amao, Sustainable Energy Fuels 2023, 7, 360.
  3. Y. Kita and Y. Amao, Bull. Chem. Soc. Jpn., 2023, 96, 328.
  4. Y. Kita and Y. Amao, Green Chem., 2023, 25, 2699.