Chem-bio interface design for rapid conversion of CO2 to bioplastics in an integrated system

•CO2 conversion via EMC2 intermediate•Soluble C2 intermediates play critical roles in the efficient integration•Systematic design enables continuous and rapid of CO2 to bioproducts•EMC2 produces PHA with substantially improved productivity product chain length The research uniquely addresses two daunting challenges our generation faces: global climate change plastic waste accumulation. We demonstrated an route for converting biodegradable plastics a systematic electrocatalysis, chemical-biological interface, microbes. integration chemical biological conversions must overcome intermediate incompatibility, harsh catalysis conditions, inefficient mass, energy, electron transfers. This study overcomes these by exploiting soluble two-carbon molecules as from electrocatalytic reduction bioconversion. These are better carriers electrons facilitate mass transfer, can readily enter primary metabolism building blocks bioproduction. Moreover, achieved integrated, continuous, microbial biomass production record-level productivity. Integrating catalytic bioconversion could advance carbon capture utilization mitigate change. However, state-of-the-arts limited transfers, unfavorable metabolic kinetics, inadequate molecular blocks. barriers (chem-bio) microorganisms enable electro-microbial (EMC2) intermediates. metabolism, have less toxicity, carry more energy electrons, serve many microorganisms. multi-tier chem-bio interface delivered system achieve 6 8 times increase compared C1 hydrogen-driven routes, respectively. multi-module synthetic biology produced medium-chain-length polyhydroxyalkanoates (PHAs), polymers, representing much higher than platforms based on intermediates, hydrogen, or electrons. synthesis fuels, chemicals, materials is fundamental human society.1Ort D.R. Merchant S.S. Alric J. Barkan A. Blankenship R.E. Bock R. Croce Hanson M.R. Hibberd J.M. Long S.P. et al.Redesigning photosynthesis sustainably meet food bioenergy demand.Proc. Natl. Acad. Sci. USA. 2015; 112: 8529-8536https://doi.org/10.1073/pnas.1424031112Crossref PubMed Scopus (577) Google Scholar In biosphere, plants, algae convert through macromolecules diverse chemicals sustain their own growth feed other heterotrophic organisms. facing increasing concentration caused activities, alternative were developed manufacture valuable industrial products.2Hepburn C. Adlen E. Beddington Carter E.A. Fuss S. Mac Dowell N. Minx J.C. Smith P. Williams C.K. technological economic prospects removal.Nature. 2019; 575: 87-97Crossref (755) Even though has successfully converted into selective compounds (e.g., urea) at commercial scale, scope still limited. Such challenge be coupling electrochemical novel routes produce macromolecules, multi-carbon commodity which leverages biosynthesis pathways while circumventing low efficiencies photosynthesis.3Zhang Dai S.Y. Yuan J.S. Producing “molecules life” hybrid relay.Chem. 2021; 7: 3200-3202https://doi.org/10.1016/j.chempr.2021.11.018Abstract Full Text PDF (4) Scholar,4Overa Feric T.G. Park A.-H.A. Jiao F. Tandem processes dioxide utilization.Joule. 5: 8-13https://doi.org/10.1016/j.joule.2020.12.004Abstract (36) Scholar,5Cai T. Sun H. Qiao Zhu L. Zhang Tang Z. Wei X. Yang Q. al.Cell-free chemoenzymatic starch dioxide.Science. 373: 1523-1527https://doi.org/10.1126/science.abh4049Crossref (164) Scholar,6Claassens N.J. Sánchez-Andrea I. Sousa D.Z. Bar-Even Towards sustainable feedstocks: A guide donors fixation.Curr. Opin. Biotechnol. 2018; 50: 195-205https://doi.org/10.1016/j.copbio.2018.01.019Crossref (55) Scholar,7Li Opgenorth P.H. Wernick D.G. Rogers Wu T.Y. Higashide W. Malati Huo Y.X. Cho K.M. Liao Integrated electromicrobial alcohols.Science. 2012; 335: 1596https://doi.org/10.1126/science.1217643Crossref (520) scientific therefore identification optimal fixation bioproduction.6Claassens Earlier work established that reduced inorganic one-carbon (C1) such CO syngas high Faradaic efficiency (FE) (route 1 Figure 1A), further fed bioconversion.8Haas Krause Weber Demler M. Schmid G. Technical involving electrolysis fermentation.Nat. Catal. 1: 32-39https://doi.org/10.1038/s41929-017-0005-1Crossref (351) Although anaerobic CO-utilizers efficient, gas-to-liquid transfer rate, electron-carrying capacity CO, strain choices profiles, often slower bioproduction rates those Pseudomonas putida (Figure 1A).9Abubackar H.N. Veiga M.C. Kennes Biological monoxide: rich gases bioethanol.Biofuels Bioprod. Bioref. 2011; 93-114https://doi.org/10.1002/bbb.256Crossref (182) To some challenges, prior electrocatalytically like formate bioconversions 2A 1A). contains lower content methanol ethanol due its structure. assimilation serine cycle improve efficiency. recently proposed reductive glycine pathway (rGlyP)10Bar-Even Formate assimilation: architecture natural pathways.Biochemistry. 2016; 55: 3851-3863https://doi.org/10.1021/acs.biochem.6b00495Crossref (96) Scholar,11Claassens Bordanaba-Florit Cotton C.A.R. De Maria Finger-Bou Friedeheim Giner-Laguarda Munar-Palmer Newell Scarinci al.Replacing Calvin Cupriavidus necator.Metab. Eng. 2020; 62: 30-41https://doi.org/10.1016/j.ymben.2020.08.004Crossref (56) Scholar,12Sánchez-Andrea Guedes I.A. Hornung B. Boeren Lawson C.E. Claassens Stams A.J.M. allows autotrophic Desulfovibrio desulfuricans.Nat. Commun. 11: 5090https://doi.org/10.1038/s41467-020-18906-7Crossref (87) Scholar,13Yishai O. Bouzon Döring V. vivo Escherichia coli.ACS Synth. Biol. 2023-2028https://doi.org/10.1021/acssynbio.8b00131Crossref (98) ATP empower used substrate 1; Table S1). Nevertheless, inherent content, formate’s remains according previous analysis, regardless go (Table S1).14Claassens Kopljar D. Making quantitative sense production.Nat. 2: 437-447https://doi.org/10.1038/s41929-019-0272-0Crossref (111) particular, relatively 1) make optimized aerobic fermentation. As formate, carries per 2B use carrier challenging. On one hand, kinetics using NAD+ acceptor redox potential oxidation.6Claassens even quinone-dependent dehydrogenase (MDH) it lowers overall dissipation quinones.14Claassens 2 leveraging cell-free system, where coupled enzymatic covert starch.5Cai chemo-enzymatic advances enzyme yet fails integrated production. temperature conditions incompatible biocatalysis, leads disjointed syntheses.3Zhang steps themselves also separated, activity only last few hours.5Cai Besides reduction, another relies direct indirect usage electrode microbes reduce 5 studies been carried 5, process typically suffers rate between microorganism, products short-chain small applications, biochemical Wood-Ljungdahl (W-L pathway).15Satanowski path fixing CO2: compounds, upgraded fermentation, become key valorization chemicals.EMBO Rep. 21e50273https://doi.org/10.15252/embr.202050273Crossref (21) Scholar,16Anwer A.H. Khan Umar M.F. Rafatullah M.Z. Electrodeposited biocathode-based electro-catalysis biofuels.Membranes. 223https://doi.org/10.3390/membranes11030223Crossref (6) thus requires large surface area volumetric chemolithotrophic, exoelectrogenic, acetogenic microbes.17Prévoteau Carvajal-Arroyo Ganigué Rabaey K. Microbial electrosynthesis forever promise?.Curr. 48-57Crossref (173) Furthermore, 6, 1A) bypass utilizes electrochemically generated hydrogen drive Ralstonia eutropha (also known necator).18Liu Colón B.C. Ziesack Silver P.A. Nocera Water splitting–biosynthetic exceeding photosynthesis.Science. 352: 1210-1213https://doi.org/10.1126/science.aaf5039Crossref (633) titer, fermentation fundamentally slow oxidation, Calvin-Benson regeneration, RuBisCo fixation.6Claassens choice species hydrogenotrophic growth.3Zhang Recent copper-based catalysts opened new avenues address fixation.19Dinh C.T. Burdyny Kibria M.G. Seifitokaldani Gabardo C.M. García de Arquer F.P. Kiani Edwards J.P. Luna Bushuyev O.S. al.CO2 electroreduction ethylene hydroxide-mediated copper abrupt interface.Science. 360: 783-787https://doi.org/10.1126/science.aas9100Crossref (1228) Scholar,20Wang Wang Dinh C.-T. Ozden Li Y.C. Nam D.-H. Liu Y.-S. Wicks al.Efficient electrically powered CO2-to-ethanol suppression deoxygenation.Nat. Energy. 478-486https://doi.org/10.1038/s41560-020-0607-8Crossref (252) Scholar,21Overa Ko B.H. Zhao Y. Electrochemical approaches chemicals: journey toward practical applications.Acc. Chem. Res. 2022; 638-648https://doi.org/10.1021/acs.accounts.1c00674Crossref (45) Scholar,22Kuhl K.P. Cave E.R. Abram D.N. Jaramillo T.F. New insights metallic surfaces.Energy Environ. 7050-7059https://doi.org/10.1039/c2ee21234jCrossref (2046) Scholar,23Gu Shen Chen Ji C2+ alcohols defect-site-rich Cu Surface.Joule. 429-440https://doi.org/10.1016/j.joule.2020.12.011Abstract (102) 3 not amenable bioconversion, others 4A acetate 4B substrates broader application.24Zhu Ma Kang Zheng Han Carbon over copper-cuprous oxide derived electrosynthesized complex.Nat. 10: 3851https://doi.org/10.1038/s41467-019-11599-7Crossref (217) Both donation formate.14Claassens both acetyl-CoA three rapidly sources 4, fewer favorable bioproducts longer chain. faster conversion, cell growth, bioproduct yield adaptation, biocompatibility current systems (routes 1, 2, 1A; S2). multi-step bioconversion,25Hu Chakraborty Kumar Woolston Emerson Stephanopoulos bioprocess gaseous liquids.Proc. 113: 3773-3778https://doi.org/10.1073/pnas.1516867113Crossref (125) Scholar,26Lehtinen Efimova Tremblay P.-L. Santala Production long alkyl esters electricity two-stage bacterial process.Bioresour. Technol. 2017; 243: 30-36https://doi.org/10.1016/j.biortech.2017.06.073Crossref (35) Scholar,27Al Rowaihi I.S. Kick Grötzinger S.W. Burger Karan Weuster-Botz Eppinger Arold S.T. gas liquid bioplastic.Bioresour. 61-68https://doi.org/10.1016/j.biteb.2018.02.007Crossref (19) us maximize benefits step carrying, efficiency, drastically rate. Despite potential, electrocatalysis before. No concept feasibility, overcame this study, we designed implemented 4 namely seamless chemical, cellular, levels, enabling With broadly adopted putida. innovative platform significantly state-of-the-art 6) photosynthetic systems. highlighted broad applicability macromolecule products. four-tier reaction (CO2RR) 1B). first tier focuses selection electrolyzer, catalysts, electrolytes need ensure CO2RR under biocompatible conditions. second sure does interfere third fourth efficiently channel tricarboxylic acid (TCA) enhance flux target will complete electrotrophic CO2, starting point generate sufficient bio-amicable constraints require electrolytes, 2A). First, flow electrolyzer equipped diffusion electrodes (GDEs) was selected production, considering potentially found cells GDE setting density conventional H-cell, feeding limited.21Overa Scholar,28Lees E.W. Mowbray B.A.W. Parlane F.G.L. Berlinguette C.P. Gas membranes electrolysers.Nat. Rev. Mater. 55-64https://doi.org/10.1038/s41578-021-00356-2Crossref (105) Second, critical. When CO2RR, whole operate cascade mode salt solution flows same catholyte media support growth. electrolyte needs suited cultivation. Frequently extreme alkaline solutions microorganism Considering neutral stable pH environment, investigated solutions. bicarbonate contained mixed NaHCO3 KHCO3 Na/K ratio suitable proven effective CO2RR.29Ren Joulié Salvatore Torbensen Robert Molecular electrocatalysts mediate fast, cell.Science. 365: 367-369https://doi.org/10.1126/science.aax4608Crossref (442) “basal” mainly composed phosphate buffer (NaH2PO4 + K2HPO4 NaCl), widely but electrocatalysis. maintained close 7 allow integration, total ion concentrations kept minimize differences resistance. evaluate compatibility, source. 7.2 (with air bubbling), remained minimal after 72 h. While basal solution, had shown significant within 24 h 2B). prioritized performances identify best catalysts. Third, configuration productivity, especially biologically compatible several typical including CuO, Cu2O, Cu–B (copper NaBH4), none them appreciable when electrolyte. showed It likely undergo reconstruction process. strongly coordinating anions interact alternate properties, favor well hydrogen.30Zhao Canepa Yesibolati M.N. Sherburne Xu Sritharan Loo J.S.C. Ager III, J.W. al.Phosphate tuned electrodeposition promoted formic selectivity reduction.J. 11905-11916https://doi.org/10.1039/C7TA01871ACrossref Based discoveries, hypothesized maintain properties electrolyte, oxide-based chemically pre-reduced catalysts.31Nitopi Bertheussen Scott S.B. Engstfeld A.K. Horch Seger Stephens I.E.L. Chan Hahn al.Progress perspectives aqueous electrolyte.Chem. 119: 7610-7672https://doi.org/10.1021/acs.chemrev.8b00705Crossref (1774) catalyst, important consideration cathode diffusion. sputtering method deposit materials, coating thin layer metals substrates, forming conductive layer. various porous layers (GDLs), non-conductive ones, GDE. Two Cu-based GDEs polytetrafluoroethylene film (PTFE film, catalyst denoted Cu/PTFE) paper (Sigracet 28 BC, Cu/28BC), Scanning electronic microscope (SEM) images confirmed uniformly coated around GDLs (Figures 2C 2D). morphologies vary original powder X-ray diffraction (XRD) analysis ratios (100) facets 2E), proving reliable repeatable fabricating electrodes. then evaluated designs (basal solution) electrocatalysis-favorable electrolytes. 2F shows FE densities ranging 100 200 mA cm−2, comparable relevant densities. main ethanol, amount 1-propanol co-produced. Compared (left group, 2F), phosphate-based (middle 2F). reached 15%, indicating subsequent grows 2B), CO2RR. t