Transcriptomic and metabolomic adaptation of Nannochloropsis gaditana grown under different light regimes

Omic technologies are a major source of information in understanding the cellular processes while their employment
for studying microalgal biomass and productivity is rapidly expanding. Microalgae are known for their
complex cellular metabolism. Environmental conditions affect intensely both their metabolic and transcriptomic
profiles, resulting in production of numerous compounds with applications in pharmaceuticals, cosmetics, nutrition
and biofuel. In an attempt to detect global changes occurring during environmental light alteration, an
integrated omics approach was employed while the results were evaluated using different statistical approaches.
An RT-qPCR based platform was utilized for the targeted transcript profiling of Nannochloropsis gaditana genes
involved in primary and secondary metabolism, while the metabolite profiles were analyzed by GC–MS and GCFID
analytical methods. The combined transcriptomic and metabolomic results revealed extensive metabolic
adaptations triggered by different chromatic qualities of light. In summary, an overall induction in both transcripts
and metabolites, involved mainly in amino acid metabolism, was observed under red filtered light. Blue
filtered light provoked decreased carbohydrate concentration but elevated polyunsaturated fatty acids content.
Moreover, green filtered light induced the lowest responses in metabolite and gene transcript levels, indicating
that its photons are poorly absorbed by N. gaditana. The current work suggests that spectral light changes leading
to biochemical and metabolic manipulation of microalga N. gaditana can be accomplished by light filtering of
solar irradiance, a cost-effective method which could be routinely applied in large scale photobioreactor cultivating
systems.