Prochlorococcus play a crucial role in the ocean's biogeochemical cycling, but it remains controversial how they will respond to global warming. Here we assessed the response to temperature (22-30°C) of the growth dynamics and gene expression profiles of a Red Sea Prochlorococcus strain (RSP50) in a non-axenic culture. Both the specific growth rate (0.55 - 0.80 d-1) and cell size (0.04 to 0.07 μm3) of Prochlorococcus increased significantly with temperature. The primary production released extracellularly ranged from 20 to 34%, with humic-like fluorescent compounds increasing up to 5-fold as Prochlorococcus reached its maximum abundance. At 30°C, genes involved in carbon fixation such as CsoS2 and CsoS3 and photosynthetic electron transport including PTOX were downregulated, suggesting a cellular homeostasis and energy saving mechanism response. In contrast, PTOX was found upregulated at 22 and 24°C. Similar results were found for transaldolase, related to carbon metabolism, and citrate synthase, an important enzyme in the TCA cycle. Our data suggest that in spite of the currently warm temperatures of the Red Sea, Prochlorococcus can modulate its gene expression profiles to permit growth at temperatures lower than its optimum temperature (28°C) but is unable to cope with temperatures exceeding 30°C.
Bibliographical noteKAUST Repository Item: Exported on 2022-12-28
Acknowledgements: This work was supported by King Abdullah University of Science and Technology (KAUST) baseline to X.A.G.M. We would like to acknowledge Miguel Viegas for analyzing Chlorophyll adata. We would like to thank Eman Sabbagh, Ghaida Hadaidi, Saeed Amin, and Najwa Al-Otaibi for their assistance with sample filtration. We would like also to thank KAUST Bioscience Core Lab (BCL) for sequencing.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics