Inorganic and organic carbon utilization by extremophile red algae

Unicellular algae are a highly diverse group of photosynthetic microorganisms that inhabit a wide range of diverse habitats. As the only photosynthetic eukaryotes, red algae of the class Cyanidiales thrive in extreme environments with low pH 0-4, high temperatures (up to 56°C) and high salinity making them ideal candidates for large-scale cultivation and industrial applications. 

All three genera of Cyanidiales (Cyanidioschyzon, Cyanidium and Galdieria) grow photoautotrophically using inorganic CO₂ as a carbon source. However, Galdieria has evolved the ability to import and metabolize a wide range of organic carbon sources enabling heterotrophic and mixotrophic lifestyles. We want to understand (i) how inorganic carbon is efficiently fixed under low dissolved CO₂ conditions (low pH), (ii) if and how simultaneous carbon acquisition through photosynthetic CO₂ fixation and respiration of organic carbon facilitate mixotrophy in Galdieria, and (iii) how the mechanisms investigated in (i) and (ii) can be utilized or manipulated to increase growth rates and algal biomass. For this purpose, we perform comparative genomics of different algal strains, transcriptomic analyses (RNA-Seq) under different growth conditions, as well as analysis of steady-state metabolite levels and metabolic fluxes using isotope labeled metabolites by GC-MS and IC-MS.

Researcher: Philipp Westhoff