How diatom blooms are being formed: Identifying the genetic underpinnings of fast growth.

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Diatoms are responsible for about 25% of global carbon fixation as a result of their successful opportunistic 'bloom and bust' life cycle, which means they quickly dominate phytoplankton communities when conditions become favourable. A rapidly-changing environment has been regarded as the most important driver for diatoms' lifestyle. Decades of research confirm the importance of light, temperature and nutrients for bloom formation in the ocean. Bloom formation is characteristic for many different microalgal species in the ocean. They are able to quickly build up high cell concentrations and therefore biomass if conditions become favourable, which particularly is known from toxic algal blooms close to the shore. These blooms are quite often caused by a combination of elevated temperatures and high concentrations of nutrients. However, the majority of algal blooms in the ocean are not caused by toxic species. Most oceanic microalgae form seasonal blooms in spring and autum, which fuel the entire marine food web. The significance of this seasonal process on a global scale even visible from space is the reason why many different groups from all over the world have worked for decades to better understand how these blooms are being formed. Much has been learned from these studies over the past decades but our group has for the first time provided evidence that a specific conserved key regulator protein and a wider network of many still unknown proteins need to be present in order to be able for diatoms to form blooms. Ramifications of this discovery are significant for our understanding of bloom formation in the ocean but also for biotechnological applications based on microalgae (e.g. biofuel). This fundamental and new knowledge can help us to optimize growth of algae by means of reverse genetics in order to produce any algal product more efficiently and therefore to a cheaper prize. This small grant application aims to obtain a new piece of knowledge to better understand how one single protein and its genetic network can translate favorable environmental conditions into fast growth. We want to investigate the mechanism of action of the gene product of our bloom inducer gene (BIG1). Preliminary evidence shows that the BIG1 protein binds to DNA but we don't know whether it directly binds or via an interacting protein. Another open question is where it binds on the DNA. This grant application will help us to answer how and where the gene product of BIG1 binds to DNA and therefore activates other genes involved in cell division and therefore fast growth. This knowledge is essential for a better understanding of the genetic underpinnings of bloom formation in diatoms but also for biotechnological improvement of algal growth for any kind of product derived from marine microalgae.