Present address: Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA.
Molecular analysis of the phosphorus starvation response in Trichodesmium spp.
Article first published online: 25 JUN 2009
© 2009 Society for Applied Microbiology and Blackwell Publishing Ltd
Volume 11, Issue 9, pages 2400–2411, September 2009
How to Cite
Orchard, E. D., Webb, E. A. and Dyhrman, S. T. (2009), Molecular analysis of the phosphorus starvation response in Trichodesmium spp. Environmental Microbiology, 11: 2400–2411. doi: 10.1111/j.1462-2920.2009.01968.x
- Issue published online: 4 SEP 2009
- Article first published online: 25 JUN 2009
- Received 7 January, 2009; accepted 8 May, 2009.
The marine diazotroph Trichodesmium is a major contributor to primary production and nitrogen fixation in the tropical and subtropical oceans. These regions are often characterized by low phosphorus (P) concentrations, and P starvation of Trichodesmium could limit growth, and potentially constrain nitrogen fixation. To better understand how this genus responds to P starvation we examined four genes involved in P acquisition: two copies of a high-affinity phosphate binding protein (pstS and sphX) and two putative alkaline phosphatases (phoA and phoX). Sequence analysis of these genes among cultured species of Trichodesmium (T. tenue, T. erythraeum, T. thiebautii and T. spiralis) showed that they all are present and conserved within the genus. In T. erythraeum IMS101, the expression of sphX, phoA and phoX were sensitive to P supply whereas pstS was not. The induction of alkaline phosphatase activity corresponded with phoA and phoX expression, but enzyme activity persisted after the expression of these genes returned to basal levels. Additionally, nifH (nitrogenase reductase; involved in nitrogen fixation) expression was downregulated under P starvation conditions. These data highlight molecular level responses to low P and lay a foundation for better understanding the dynamics of Trichodesmium P physiology in low-P environments.