title: Phosphite utilization by the marine picocyanobacterium Prochlorococcus MIT9301.
abstract: Primary productivity in the ocean's oligotrophic regions is often limited by phosphorus (P) availability. In low phosphate environments, the prevalence of many genes involved in P acquisition is elevated, suggesting that the ability to effectively access diverse P sources is advantageous for organisms inhabiting these regions. Prochlorococcus, the numerically dominant primary producer in the oligotrophic ocean, encodes high-affinity P transporters, P regulatory proteins and enzymes for organic phosphate utilization, but its ability to use reduced P compounds has not been previously demonstrated. Because Prochlorococcus strain MIT9301 encodes genes similar to phnY and phnZ, which constitute a novel marine bacterial 2-aminoethylphosphonate (2-AEPn) utilization pathway, it has been suggested that this organism might use 2-AEPn as an alternative P source. We show here that although MIT9301 was unable to use 2-AEPn as a sole P source under standard culture conditions, it was able to use phosphite. Phosphite utilization by MIT9301 appears to be mediated by an NAD-dependent phosphite dehydrogenase encoded by ptxD. We show that phosphite utilization genes are present in diverse marine microbes and that their abundance is higher in low-P waters. These results strongly suggest that phosphite represents a previously unrecognized component of the marine P cycle.
authors: Department of Civil and Environmental Engineering Division of Biological Engineering Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA. chon@mit.edu
authors: Asunción
authors: A
authors: Martínez
authors: Marcia S
authors: MS
authors: Osburne
authors: Adrian K
authors: AK
authors: Sharma
authors: Edward F
authors: EF
authors: DeLong
authors: Sallie W
authors: SW
authors: Chisholm
mesh_terms: D001419:Bacteria / Q000378:metabolism; D018977:Micronutrients / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism; D009792:Oceans and Seas; D017905:Phosphites / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D048929:Prochlorococcus / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014131:Trace Elements / Q000378:metabolism*
chemical_list: D018977:Micronutrients; D017905:Phosphites; D014131:Trace Elements; D010758:Phosphorus; D009247:NADH, NADPH Oxidoreductases; C429539:NAD phosphite oxidoreductase