Biogeochemical fingerprinting of magnetotactic bacterial magnetite Perez Huerta, Alberto Cappelli, Chiara Jabalera Ruz, Ylenia María Prozorov, Tanya Jiménez López, Concepción Bazylinski, Dennis A. Biomagnetite Bacteria Biogeochemistry Atom probe tomography Magnetofossils Data Availability. All data related to the manuscript, including samples and aspects of methodology, are included in the main manuscript or as part of SI Appendix. Requests for additional data (i.e., APT data files), details of protocols, materials, and for any questions related to the manuscript, should be addressed to the corresponding author, Dr. Alberto Pérez-Huerta (aphuerta@ua.edu). Original IVAS files (RHIT and HITS) data are available in Figshare (45). ACKNOWLEDGMENTS. This work is supported by NSF grants EAR-1647012 and EAR-150779 grants awarded to A.P.-H. D.A.B. is supported by NSF grant EAR-1423939. C.J.L. wishes to thank Junta de Andalucía (Spain) projects B-BIO-432-UGR20 and P20_00208 and Ministerio de Ciencia y Educación (Spain) projects PDC2021-121135-I00 and CGL 2016-76723. T.P. acknowledges support of Laboratory Directed Research and Development Program through Ames Laboratory. This work at the Ames National Laboratory was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. Electron microscopy work (FIBelectron microscopy and scanning and transmission electron microscopy imaging) was performed at the UA AARC, the Ames National Laboratory, and the Universidad de Granada. Electron microscopy imaging and FIB work in the Ames Laboratory was performed using instruments in the Sensitive Instrument Facility. The Ames National Laboratory is operated for the U.S. Department of Energy by Iowa State University under contract No. DE-AC02-07CH11358. The authors also acknowledge the work of Drs. Fernando Laiginhas and Alejandra Londoño-Calderon in FIB-scanning electron microscopy sample preparation, Dr. Matthew Lynn for help with FIB training and specimen preparation, and the invaluable assistance of Dr. Lynda Williams and Dr. Maitrayee Bose for the SIMS and nano-SIMS analyses, respectively, using instruments in the NSF-supported Multiuser Facility at Arizona State University. This article contains supporting information online at http://www.pnas.org/lookup/suppl/doi:10.1073/pnas. 2203758119/-/DCSupplemental. Biominerals are important archives of the presence of life and environmental processes in the geological record. However, ascribing a clear biogenic nature to minerals with nanometer-sized dimensions has proven challenging. Identifying hallmark features of biologically controlled mineralization is particularly important for the case of magnetite crystals, resembling those produced by magnetotactic bacteria (MTB), which have been used as evidence of early prokaryotic life on Earth and in meteorites. We show here that magnetite produced by MTB displays a clear coupled C–N signal that is absent in abiogenic and/or biomimetic (protein-mediated) nanometer-sized magnetite. We attribute the presence of this signal to intracrystalline organic components associated with proteins involved in magnetosome formation by MTB. These results demonstrate that we can assign a biogenic origin to nanometer-sized magnetite crystals, and potentially other biominerals of similar dimensions, using unique geochemical signatures directly measured at the nanoscale. This finding is significant for searching for the earliest presence of life in the Earth’s geological record and prokaryotic life on other planets 2022-09-26T08:23:44Z 2022-09-26T08:23:44Z 2022-07-28 info:eu-repo/semantics/article Pérez-Huerta, A., Cappelli, C., Jabalera, Y., Prozorov, T., Jimenez-Lopez, C., & Bazylinski, D. A. Biogeochemical fingerprinting of magnetotactic bacterial magnetite. 119 (31) e2203758119 [https://doi.org/10.1073/pnas.2203758119] https://hdl.handle.net/10481/76959 10.1073/pnas.2203758119 eng http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess Attribution-NonCommercial-NoDerivatives 4.0 Internacional National Academy of Sciences