title: Phosphite utilization by the globally important marine diazotroph Trichodesmium.
abstract: Species belonging to the filamentous cyanobacterial genus Trichodesmium are responsible for a significant fraction of oceanic nitrogen fixation. The availability of phosphorus (P) likely constrains the growth of Trichodesmium in certain regions of the ocean. Moreover, Trichodesmium species have recently been shown to play a role in an emerging oceanic phosphorus redox cycle, further highlighting the key role these microbes play in many biogeochemical processes in the contemporary ocean. Here, we show that Trichodesmium erythraeum IMS101 can grow on the reduced inorganic compound phosphite as its sole source of P. The components responsible for phosphite utilization are identified through heterologous expression of the T. erythraeum IMS101 Tery_0365-0368 genes, encoding a putative adenosine triphosphate (ATP)-binding cassette transporter and nicotinamide adenine dinucleotide (NAD)-dependent dehydrogenase, in the model cyanobacteria Synechocystis sp. PCC6803. We demonstrate that only combined expression of both the transporter and the dehydrogenase enables Synechocystis to utilize phosphite, confirming the function of Tery_0365-0367 as a phosphite uptake system (PtxABC) and Tery_0368 as a phosphite dehydrogenase (PtxD). Our findings suggest that reported uptake of phosphite by Trichodesmium consortia in the field likely reflects an active biological process by Trichodesmium. These results highlight the diversity of phosphorus sources available to Trichodesmium in a resource-limited ocean.
authors.affiliation: Ocean and Earth Sciences, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, European Way, Southampton, SO14 3ZH, UK.
authors.forename: Despo
authors.initials: D
authors.lastname: Polyviou
authors.affiliation: Ocean and Earth Sciences, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, European Way, Southampton, SO14 3ZH, UK.|Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield, S10 2TN, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hitchcock
authors.affiliation: Ocean and Earth Sciences, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, European Way, Southampton, SO14 3ZH, UK.
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Baylay
authors.affiliation: Ocean and Earth Sciences, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, European Way, Southampton, SO14 3ZH, UK.
authors.forename: C Mark
authors.initials: CM
authors.lastname: Moore
authors.affiliation: Ocean and Earth Sciences, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, European Way, Southampton, SO14 3ZH, UK.
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Bibby
mesh_terms: D059001:Aquatic Organisms / Q000378:metabolism*; D000458:Cyanobacteria / Q000254:growth & development / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D023061:Gene Order; D009586:Nitrogen Fixation; D009792:Oceans and Seas; D017905:Phosphites / Q000378:metabolism*
chemical_list: D017905:Phosphites