Prochlorococcus and Synechococcus are pico-sized cyanobacteria that play a fundamental role in oceanic primary production, being particularly important in warm, nutrient-poor waters. Their potential response to nutrient enrichment is expected to be contrasting and to differ from larger phytoplankton species. Here, we used a metagenomic approach to characterize the responses to nutrient enrichment in the community of picocyanobacteria and to analyze the cyanophage response during a mesocosms experiment in the oligotrophic Red Sea. Natural picoplankton community was dominated by Synechococcus clade II, with marginal presence of Prochlorococcus (0.3% bacterial reads). Increased nutrient input triggered a fast Synechococcus bloom, with clade II being the dominant, with no response of Prochlorococcus growth. The largest bloom developed in the mesocosms receiving a single initial input of nutrients, instead of daily additions. The relative abundances of cyanophage sequences in cellular metagenomes increased during the experiment from 12.6% of total virus reads up to 40% in the treatment with the largest Synechococcus bloom. The subsequent collapse of the bloom pointed to a cyanophage infection on Synechococcus that reduced its competitive capacity, and was then followed by a diatom bloom. The cyanophage attack appears to have preferentially affected the most abundant Synechococcus clade II, increasing the evenness within the host population. Our results highlight the relevance of host-phage interactions on determining population dynamics and diversity of Synechococcus populations.
|Original language||English (US)|
|Journal||Frontiers in Microbiology|
|State||Published - Jun 3 2020|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We thank Tony Merle for the flow cytometry analysis, Laura Casas and Craig Michell for the DNA extraction and library construction. Further, we thank Naroa Aldanondo, Susana Carvalho, Amr Gusti, Karie Holtermann, Ioannis Georgakakis, Nazia Mojib, and Tane Sinclair-Taylor as well as the technical personnel of the Coastal and Marine Resources Core Laboratory (CMOR) for their help in undertaking the sampling. Funding. The research reported in this paper was supported by King Abdullah University of Science and Technology through base-line funding to XI, SA, and CD, and center funding to the Red Sea Research Center and the Computational Biology Research Center.