Transcriptomic response induced by iron limitation in the cyanobacteria Synechococcus sp. PCC 7002 (BMB04)

In this study, we characterized the homeostasis of the marine cyanobacteria Synechococcus sp. PCC7002 (BMB04) growing in chemically characterized synthetic seawater with three different levels of iron limitation representative of the modern ocean. Using transcriptomic approach, we identified the sequence of physiological responses to increasing Fe limitation. Our results showed an increase in the number of dysregulated genes and in the complexity of the response to increasing Fe limitation. Genes involved in photosynthesis were strongly down-regulated under MiFeL, while membrane transporters were up-regulated. Genes involved in regulation of energy metabolism responded under strong Fe limitation, while fine metabolic regulation of co-factors expression and activation of specific cellular mechanisms to minimize oxidative stress were only observed under severe Fe limitation. Additionally, our results demonstrate the limitations in the construct of the bioreporter BMB04 that hamper its application in areas of the ocean strongly Fe limited. Overall design: Twelve samples were analyzed. Three levels of Fe limitation were tested (0.41, 0.04 and 0.003 nM inorganic Fe), each biological triplicates. The control was Fe repleted (10.9 nM inorganic Fe), in biological replicates as well.