Living and Conducting: Coating Individual Bacterial Cells with In Situ Formed Polypyrrole

Abstract

Coating individual bacterial cells with conjugated polymers to endow them with more functionalities is highly desirable. Here, we developed an in situ polymerization method to coat polypyrrole on the surface of individual Shewanella oneidensis MR‐1, Escherichia coli, Ochrobacterium anthropic or Streptococcus thermophilus. All of these as‐coated cells from different bacterial species displayed enhanced conductivities without affecting viability, suggesting the generality of our coating method. Because of their excellent conductivity, we employed polypyrrole‐coated Shewanella oneidensis MR‐1 as an anode in microbial fuel cells (MFCs) and found that not only direct contact‐based extracellular electron transfer is dramatically enhanced, but also the viability of bacterial cells in MFCs is improved. Our results indicate that coating individual bacteria with conjugated polymers could be a promising strategy to enhance their performance or enrich them with more functionalities.

Algal cell bionics as a step towards photosynthesis-independent hydrogen production

“…Recently, mesoporous microspheres 32 , platinum nanoclusters 33 , and polypyrole 34 have been employed to fabricate biohybrids capable of cell-free hydrogen production, tunable electrical conductivity or self-enhancing photoactivity. In addition, construction of bionic functional layers around living cells with ultra-thin shells of a coacervate phase 35 , semiconductors and carbon nanotubes 36 , polypyrole 37 or calcium carbonate 38 has proved to be an effective strategy for enhancing natural cellular properties and augmenting living organisms with non-natural functions.…”

Mechano-control of Extracellular Electron Transport Rate via Modification of Inter-heme Coupling in Bacterial Surface Cytochrome

“…Multi-heme-mediated electron transport in outer-membrane cytochrome (OMC) complexes, referred to as extracellular electron transport (EET), is critical for bacterial bio-electrocatalysis . While past studies have increased the catalytic current by selecting specific electrode materials or redox mediators, enhancement of the electron flux per OMC remains a challenge. − Extensive efforts in delineating the structures of cytochrome complexes and simulation studies have unveiled that the EET rate is associated with inter-heme distances and spatial orientations, referred to as heme coupling. , Briefly, appropriate heme coupling contributed to a higher EET rate, which is supported by the observation of the inter-heme electron transport kinetics varying up to even a thousand times because of the improved π-stacking between hemes . Therefore, modification of heme coupling is a promising strategy, and differences in heme alignment have previously resulted in >10-fold change in the electron flux per OMC .…”

Conjugated Polyelectrolyte/Bacteria Living Composites in Carbon Paper for Biocurrent Generation

“…[16,17] Other methods for developing 3D electrodes have relied on the design of electrodes with shape-adaptability. [18,19] Desirable properties include biocompatibility, ease of assembly, conductivity in aqueous media, and tunable optoelectronic properties while maintaining diffusion of nutrients and waste. Strategically designed organic semiconductors (OSC) can help in this regard.…”

“…A living biocomposite was also fixed on carbon cloth by encapsulating S. oneidensis MR-1 with polypyrrole (PPy), resulting in a 5-fold biocurrent extraction increase over control experiments. [18] As a final example, graphene oxide was combined with S. oneidensis MR-1 to create hybridized biofilms on the terminal electron acceptor that increased biocurrent generation through increased biomass and EASA usage. [29,30] Conjugated polyelectrolytes (CPEs) can be designed to be water-soluble and thereby offer the possibility of exploring their integration with bacteria in aqueous media.…”