Researchers find Shewanella transfers electrons

Shewanella oneidensis is a bacterium that researchers have studied for years because it can move electrons across its cell envelope and exchange them with materials outside the cell. A new paper published April 29 in Nature Catalysis says that process can run in reverse with a semiconductor: the microbe can take up electrons from shaped hematite particles. The work adds a directly measured case of electron transfer at a microbe-semiconductor interface, a system researchers are building for solar-to-chemical conversion. The study circulated more widely on May 22 after social-media posts linked to the paper and described the result as bacteria “injecting” electrons into semiconductors, but the paper itself is about quantifying reverse electron transfer between the microbe and hematite. ### Which organism and material are actually in the paper? The paper names Shewanella oneidensis MR-1 and shaped hematite, an iron-oxide semiconductor, as the paired biological and inorganic components. Nature’s summary says the researchers used a multimodal optical imaging platform to probe charge-transfer efficiency between the bacterium and hematite with different exposed crystal facets. Cornell Chronicle described Shewanella oneidensis in February as “the most well-known and extensively studied microbe used for electron transport,” and said Cornell researchers had been exploring how electroactive bacteria interact with semiconducting materials. (nature.com) That earlier Cornell report involved Peng Chen and Buz Barstow and helps place the new paper in an ongoing line of work on microbe-semiconductor interfaces. ### Did the researchers show electrons going into the bacteria or out of them? (nature.com) Nature Catalysis says the team quantified “reverse extracellular electron-transfer capabilities” of Shewanella oneidensis MR-1 through non-hydrogen-mediated pathways. In plain terms, that means the direction of charge flow examined here is from the semiconductor side toward the microbe, not the more familiar case of the bacterium dumping electrons onto an external surface. A 2021 Communications Biology paper had already identified a pathway for electron uptake in Shewanella, showing the organism’s electron-transport machinery can operate in that inward direction. (news.cornell.edu) The new Nature Catalysis paper appears to extend that picture to a shaped hematite interface and to direct imaging of efficiency at very small scales. That comparison is an inference from the two papers, not a quote from either study. ### What is new beyond the basic idea that Shewanella moves electrons? (nature.com) The April 29 paper says it measured the interaction at single-particle and single-cell levels, in vivo and operando. Nature’s summary also says the researchers found a facet-dependent effect: hematite’s {110} facets showed stronger cell-binding ability and higher charge-transfer efficiency than the comparison facet. A March 2025 Cornell report on a related quantum-dot system said researchers had previously identified two routes for electrons entering a microbe from a semiconductor nanocrystal — a direct path and an indirect path via shuttle molecules. (nature.com) That work did not use hematite, but it shows the same group had already been trying to resolve exactly how electrons cross the nano-bio interface. ### Does this mean bacteria are now making solar fuels? The Nature summary says understanding charge transfer at microbe-semiconductor interfaces is valuable for advancing solar-to-chemical conversion. (nature.com) That is the application researchers cite, but the paper summary available publicly does not provide the kind of device-level solar-fuel efficiency figures that would show a finished energy platform. The social-media shorthand that bacteria can “inject electrons into semiconductors” compresses the result too far. (news.cornell.edu) The verified finding is narrower: researchers measured reverse electron transfer efficiency between Shewanella oneidensis MR-1 and shaped hematite and reported that the efficiency depends on which crystal facet the cells contact. ### Who did the work, and where can readers check it? Nature Catalysis lists the article as “Single-particle imaging uncovers reverse electron transfer efficiency between Shewanella oneidensis MR-1 and shaped haematite,” published April 29, 2026. (nature.com) A Cambridge chemistry profile and a research-group publications page both list the paper and its author roster, which includes Y. Liu, W. Song, W. Zhang, Y. Liang, M. Saini, Y. He, J. Zhu, Z. Chen, G. Zhang, J. Xie, X. Xu, G.C. Bazan, J.L. Foo, M.W. Chang, B. Liu and X. Mao. (nature.com) Cornell’s related coverage names Peng Chen, Tobias Hanrath and Buz Barstow in the broader effort to study electroactive bacteria with semiconducting materials. Readers looking for the primary result should start with the Nature Catalysis paper published April 29, 2026, then use the Cornell reports from March 18, 2025 and February 23, 2026 for background on the measurement methods and Shewanella’s electron-transfer machinery. (news.cornell.edu) (nature.com)