title: Mechanisms of increased Trichodesmium fitness under iron and phosphorus co-limitation in the present and future ocean.
abstract: Nitrogen fixation by cyanobacteria supplies critical bioavailable nitrogen to marine ecosystems worldwide; however, field and lab data have demonstrated it to be limited by iron, phosphorus and/or CO2. To address unknown future interactions among these factors, we grew the nitrogen-fixing cyanobacterium Trichodesmium for 1 year under Fe/P co-limitation following 7 years of both low and high CO2 selection. Fe/P co-limited cell lines demonstrated a complex cellular response including increased growth rates, broad proteome restructuring and cell size reductions relative to steady-state growth limited by either Fe or P alone. Fe/P co-limitation increased abundance of a protein containing a conserved domain previously implicated in cell size regulation, suggesting a similar role in Trichodesmium. Increased CO2 further induced nutrient-limited proteome shifts in widespread core metabolisms. Our results thus suggest that N2-fixing microbes may be significantly impacted by interactions between elevated CO2 and nutrient limitation, with broad implications for global biogeochemical cycles in the future ocean.
authors.affiliation: Marine and Environmental Biology, Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, California 90089, USA.
authors.forename: Nathan G
authors.initials: NG
authors.lastname: Walworth
authors.affiliation: Marine and Environmental Biology, Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, California 90089, USA.
authors.forename: Fei-Xue
authors.initials: FX
authors.lastname: Fu
authors.affiliation: Marine and Environmental Biology, Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, California 90089, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Webb
authors.affiliation: Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
authors.forename: Mak A
authors.initials: MA
authors.lastname: Saito
authors.affiliation: Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
authors.forename: Dawn
authors.initials: D
authors.lastname: Moran
authors.affiliation: Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Mcllvin
authors.affiliation: Marine and Environmental Biology, Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, California 90089, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Lee
authors.affiliation: Marine and Environmental Biology, Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, California 90089, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Hutchins