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Growth kinetics of marine unicellular N2-fixing cyanobacterial isolates in continuous culture in relation to phosphorus and temperature

2005; Inter-Research; Volume: 285; Linguagem: Inglês

10.3354/meps285003

1616-1599

Luisa I. Falcón, S Pluvinage, EJ Carpenter,

Marine Biology and Ecology Research

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 285:3-9 (2005) - doi:10.3354/meps285003 Growth kinetics of marine unicellular N2-fixing cyanobacterial isolates in continuous culture in relation to phosphorus and temperature Luisa I. Falcón1,2,*, Sybille Pluvinage1, Edward J. Carpenter1 1Romberg Tiburon Center for Environmental Studies, San Francisco State University, Tiburon, California 94920, USA 2Present address: Instituto de Ecología, Universidad Nacional Autónoma de México, CP 04510, México DF, Mexico *Email: falcon@miranda.ecologia.unam.mx ABSTRACT: Unicellular N2-fixing cyanobacteria from tropical marine oligotrophic environments have been proposed to be major contributors to the global N cycle but still remain poorly characterized. These organisms are likely to be limited by phosphorus availability in situ. The aim of this study was to identify growth kinetics of isolates from the tropical North Atlantic and subtropical North Pacific in relation to phosphorus and temperature in continuous cultures. Cells from the Atlantic measured 2.5 µm in diameter (A-2.5). Genetically identical isolates from the Pacific showed 2 diameters depending on P-media concentrations (small: 3 µm, 1 µM PO4 [P-3] and large: 7 µm, 4 µM PO4 [P-7]). All 3 isolates were highly stenothermal, and optimal growth temperatures ranged between 26 and 30°C. Small cells (A-2.5 and P-3) had lower half-saturation constants (Ks) for PO4 than large cells (P-7) (0.06 to 0.21 µM vs. 0.20 to 0.25 µM). Maximum growth rates and N:P ratios increased with temperature for all isolates; N:P ratios were close to Redfield ratios (N:P = 16) when isolates approached maximum growth rates. N2-fixation activity did not vary between growth rates, but did increase with temperature; rates were consistently lower than previously published rates for the same isolates under non-P-limiting conditions. From these studies, we conclude that both Atlantic and Pacific unicellular cyanobacteria that have the capacity to fix N2 have a limited temperature range for growth and that smaller sized isolates could be better adapted for conditions of phosphorus limitation. KEY WORDS: Growth kinetics · Phosphorus · Temperature · Unicellular cyanobacteria · N2 fixation Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 285. Online publication date: January 19, 2005 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2005 Inter-Research.