ABSTRACT
We report a rationally designed membrane-intercalating conjugated oligoelectrolyte (COE), namely COE-IC, which endows aerobic N2 -fixing bacteria Azotobacter vinelandii with a light-harvesting ability that enables photosynthetic ammonia production. COE-IC possesses an acceptor-donor-acceptor (A-D-A) type conjugated core, which promotes visible light absorption with a high molar extinction coefficient. Furthermore, COE-IC spontaneously associates with A. vinelandii to form a biohybrid in which the COE is intercalated within the lipid bilayer membrane. In the presence of L-ascorbate as a sacrificial electron donor, the resulting COE-IC/A. vinelandii biohybrid showed a 2.4-fold increase in light-driven ammonia production, as compared to the control. Photoinduced enhancement of bacterial biomass and production of L-amino acids is also observed. Introduction of isotopically enriched 15 N2 atmosphere led to the enrichment of 15 N-containing intracellular metabolites, consistent with the products being generated from atmospheric N2 .
Subject(s)
Azotobacter vinelandii , Nitrogen Fixation , Ammonia , Bacteria , NitrogenABSTRACT
Interfacing bacteria as biocatalysts with an electrode provides the basis for emerging bioelectrochemical systems that enable sustainable energy interconversion between electrical and chemical energy. Electron transfer rates at the abiotic-biotic interface are, however, often limited by poor electrical contacts and the intrinsically insulating cell membranes. Herein, we report the first example of an n-type redox-active conjugated oligoelectrolyte, namely COE-NDI, which spontaneously intercalates into cell membranes and mimics the function of endogenous transmembrane electron transport proteins. The incorporation of COE-NDI into Shewanella oneidensis MR-1 cells amplifies current uptake from the electrode by 4-fold, resulting in the enhanced bio-electroreduction of fumarate to succinate. Moreover, COE-NDI can serve as a "protein prosthetic" to rescue current uptake in non-electrogenic knockout mutants.
Subject(s)
Bioelectric Energy Sources , Shewanella , Electron Transport/physiology , Electrons , Oxidation-Reduction , Electricity , Membrane Transport Proteins/metabolism , Shewanella/metabolism , Electrodes , Bioelectric Energy Sources/microbiologyABSTRACT
Fully conjugated macrocycles containing benzenoid rings rarely show global aromaticity/antiaromaticity. Herein, we report an annulene-like macrocycle CBTT and its S,S-dioxidized macrocycle DOCBTT with alternative quinoidal thiophene/1,1-dioxide thiophene and triphenyl amine moieties. They both showed temperature-dependent intramolecular dynamics and global antiaromatic character with 32π electrons at low temperature. However, CBTT and DOCBTT have different conjugated pathways.
