Present address: Department of Biology, University of Southern California, 3616 Trousdale Parkway, AHF 331, Los Angeles, CA 90089-0371, USA.
Diel rhythm of nitrogen and carbon metabolism in the unicellular, diazotrophic cyanobacterium Crocosphaera watsonii WH8501
Article first published online: 16 OCT 2009
© 2009 Society for Applied Microbiology and Blackwell Publishing Ltd
Volume 12, Issue 2, pages 412–421, February 2010
How to Cite
Mohr, W., Intermaggio, M. P. and LaRoche, J. (2010), Diel rhythm of nitrogen and carbon metabolism in the unicellular, diazotrophic cyanobacterium Crocosphaera watsonii WH8501. Environmental Microbiology, 12: 412–421. doi: 10.1111/j.1462-2920.2009.02078.x
- Issue published online: 26 JAN 2010
- Article first published online: 16 OCT 2009
- Received 17 April, 2009; accepted 31 August, 2009.
We examined the diel variation in nitrogen and carbon metabolism in Crocosphaera watsonii WH8501 at the physiological and gene expression level in order to determine the temporal constraints for N2 fixation and photosynthesis. N2 fixation and photosynthesis were restricted to the dark and light periods, respectively, during a 24 h light–dark cycle. All genes studied here except one (psbA2) showed diel variations in their expression levels. The highest variation was seen in nifH and nifX relative transcript abundance with a factor of 3–5 × 103 between light and dark periods. Photosynthesis genes showed less variation with a maximum factor of about 500 and always had high relative transcript abundances relative to other genes. At the protein level, the photosystems appeared more stable than the nitrogenase complex over a 24 h light–dark cycle, suggesting that C. watsonii retains the ability to photosynthesize during the dark period of the diel cycle. In contrast, nitrogenase is synthesized daily and exhibits peak abundance during the dark period. Our results have implications for field studies with respect to the interpretation of environmental gene expression data.