My research focuses on the biodiversity, ecology, and evolution of marine microbes, with particular emphasis on nitrogen fixation, a key process for primary production and carbon sequestration in the ocean. Throughout my career, I have been working in different research institutions (ICM-CSIC (Spain), University of California Santa Cruz (USA), CNRS/Sorbonne Université (France)), where I have explored the diversity of lifestyles and cellular organization of marine nitrogen-fixing bacteria through combining lab and field work (e.g., Tara Oceans, Malaspina expeditions), and using single-cell techniques, genomics, high-throughput sequencing, microscopy, and bioinformatics. My main goal is to ascertain how marine microbes interact each other by investigating symbioses between nitrogen-fixing bacteria and algae and, within this topic, I am particularly intrigued by nitrogen-fixing symbionts that are on the verge of becoming organelles, as they are useful emerging models to explore the early evolution of the eukaryotic cell.
Selected papers
Cornejo-Castillo, F.M., Inomura, K., Zehr, J.P., Follows, M.J. (2024) Metabolic tradeoffs constrain the cell size ratio in a nitrogen-fixing symbiosis. Cell, DOI: 10.1016/j.cell.2024.02.016.
Salas, K., Cabello, A.M., Turk-Kubo, K.A., Zehr, J.P., Cornejo-Castillo, F.M. (2023) Primer design for the amplification of the ammonium transporter genes from the uncultured haptophyte algal species symbiotic with the marine nitrogen-fixing cyanobacterium UCYN-A1. Frontiers in Microbiology. DOI: 10.3389/fmicb.2023.1130695.
Bonnet, S., Benavides, M, Le Moigne, F.A.C., (…), Cornejo-Castillo, F.M. (2023). Diazotrophs are overlooked contributors to carbon and nitrogen export to the deep ocean. The ISME Journal, DOI: 10.1038/s41396-022-01319-3.
Turk-Kubo, K.A., Gradoville, M.R., Cheung, S., Cornejo-Castillo, F.M., Harding, K., Morando, M., Mills, M., Zehr, J.P. (2022) Non-cyanobacterial diazotrophs: Global diversity, distribution, ecophysiology, and activity in marine waters. FEMS Microbiology Reviews, DOI: 10.1093/femsre/fuac046.
Cornejo-Castillo, F. M. & Zehr, J.P. (2021) Intriguing size distribution of the uncultured and globally widespread marine non-cyanobacterial diazotroph Gamma-A. The ISME Journal, DOI: 10.1038/s41396-020-00765-1.
Cornejo-Castillo, F. M. & Zehr, J.P. (2019) Hopanoid lipids may facilitate aerobic nitrogen fixation in the ocean. PNAS, DOI:10.1073/pnas.1908165116.
Cornejo-Castillo, F.M., Muñoz-Marin, MdC, Turk-Kubo, K.A., Royo-Llonch, M., Farnelid, H., Acinas, S.G., Zehr, J.P. (2019) UCYN-A3, a newly characterized open ocean sublineage of the symbiotic N2-fixing cyanobacterium Candidatus Atelocyanobacterium thalassa. Environmental Microbiology, DOI: 10.1111/1462-2920.14429
Cornejo-Castillo, F.M., Cabello, A.M., Salazar, G., (…), Acinas, S.G. (2016). Cyanobacterial symbionts diverged in the late Cretaceous towards lineage-specific nitrogen fixation factories in single-celled phytoplankton.Nature Communications, DOI:10.1038/ncomms11071.
Cabello, A.M., Cornejo-Castillo, F.M., Raho, N., (…), Massana, R. (2016). Global distribution and vertical patterns of a prymnesiophyte–cyanobacteria obligate symbiosis. The ISME Journal, DOI:10.1038/ismej.2015.147.