Physiology and transcriptome of a salt acclimated cyanobacterium- Prochlorococcus strain AS9601

  • Sumaya Al Hosani

Student thesis: Master's Thesis


The biological process of salt acclimation in salt sensitive cyanobacteria is not clearly understood. Studying and understanding salt acclimation has implications in biotechnology and ecological science. For biotechnology - understanding salt acclimation can lead to the design and use of salt-tolerant cyanobacteria for bioenergy in saline and/or brackish water. From an ecological science standpoint, understanding salt acclimation in cyanobacteria will allow us to predict the impact of rising ocean salinity due to climate change on primary production in the world's oceans. The organism Prochlorococcus strain AS9601 was chosen for this work because of its simplistic features (small genome and minimal nutrient requirement) and characteristics of its native environment. Prochlorococcus AS9601 was isolated from the Arabian Sea, an environment considered to have higher salinity and temperatures than what is reported for other seas around the world. Our experiments showed that Prochlorococcus AS9601 can sustainably grow in 5% w/v salt. Comparison of whole cell transcriptomics (RNAseq analysis) of two exponential-phase populations of AS9601 – acclimated to high salt (5% w/v) vs. normal seawater salt (3.8% w/v) enabled us to identify the major biochemical pathways in a cell that are impacted by elevated salt concentrations. Genes coding for transporters, osmolyte biosynthesis, carbon fixation and stress induced proteins were up-regulated, whereas genes coding for proteins involved in cell division, photosynthesis and fatty acid biosynthesis were down-regulated. These findings are in agreement with physiological measurements we have taken during the experiment. Namely, cells subjected to salinity stress exhibited lower photosynthetic efficiencies and slower growth rates when compared to controls.
Date of AwardMay 2014
Original languageAmerican English
SupervisorLina Yousef (Supervisor)


  • Hypothetical Protein; Cyanobacteria; RNAseq; Stress.

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