Climate change is an imminent process that will change the relations between all living organisms on Earth. Normally, more than 90% of planetary carbon is stored in algae, vegetation, and coral as biomass and organic compounds; nevertheless, the actual accumulation of anthropogenic gaseous CO2 in the atmosphere intensifies the greenhouse effect, which has increased the average temperature of the planet during the last decades. As primary producers and capable of performing photosynthesis, microalgae absorb sunlight (photons) and convert inorganic carbon (from the atmosphere or industrial emissions) into organic carbon biomass. Therefore, during the last decades, an exponential advance in research for alternative energies e.g. biofuels (in contrast to fossil fuels) and to increase the atmospheric CO2 fixation for biomass production has been achieved. This represents an alternative to confront the ongoing climate change crisis. However, nature has developed this strategy long time ago during the so-called “Great Oxidation Event” which occurred about 2.4 billion years ago when cyanobacteria ancestors dramatically changed the environment with the massive fixation of atmospheric CO2 and the use the sunlight energy to produce organic matter and O2. The sequestration of CO2 in microalgae systems has a number of advantages, like better light utilization efficiency, high growth rates, and larger biomass production comparing with terrestrial plants. Notably, this process flows in parallel with the production of a large variety of biomolecules which present potential as antioxidants, vitamins, biodiesel, or biomedical precursors. 

Microalgae are among the most ancient and diverse organisms on the planet. They result from rounds of endosymbiotic events, the very first one being the engulfment of a cyanobacterium by a heterotrophic eukaryote, from that the three contemporary algal lineages emerged: chlorophytes, glaucophytes and rhodophytes. Members of the chlorophytes and rhodophytes were engulfed by independent eukaryotic hosts resulting in lineages with secondary plastids. These events give rise to an extensive variety in the relations between the newly-born organelles and the host.

Even though the large diversification of the eukaryotic organisms, most of our bioenergetic knowledge arises from a small group of model organisms (mainly: Opisthokons, chlorophyta and rhodophyta). Studies are scare in other lineages, nevertheless, the study of organisms beyond the classical model has enriched our bioenergetic knownledge and has allowed us to answer some interesant questions.

Our research over the last decade contributed to elucidate the structure of two of the largest ATP synthases described so far: The chlorophycean and the euglenoid enzymes, both of the present stable dimeric structure.

Supercomplexes (SC) built by complexes I, III and IV and the larger respirasome (I/III2/IV) complex have been described in mitochondria from several model organism (yeast, mammals and flowering plants), but information is scarce in other lineages.

Microalgae are among the most diverse organisms on the planet. They have evolved to adapt to a wide range of environments and consequently the diversity of protein ortholog groups in algae is almost the double (67.7%) when compared with land plants (32.9%) or vertebrates (34.4%). In the case of Euglena Photosystems, both, PSI and PSII, have acquired an atypical architecture, which leads to unique functional mechanism.