**6. Conclusions**

The unicellular red alga *Galdieria* is an amazing organism, not only because of its ability to live in extreme habitats, but also because of its metabolic flexibility to grow photo-autotrophically, heterotrophically or mixotrophically on diverse carbon sources. These properties make it a suitable candidate for biotechnological applications, including those inappropriate for other organisms. The biotechnological potential of *Galdieria* lies in the tremendous variability of cultivation conditions under which it is able to grow, including the ability to accumulate toxic heavy metals as well as rare ones such as Au, Pt or lanthanides. This alga can also produce biotechnologically attractive products such as phycocyanin, glycogen, protein-rich or insoluble dietary fiber-rich additives for nutritional applications. This opens up fields for its use in a wide range of industries such as the food industry, pharmaceuticals, healthcare, waste management, the metal recycling industry, bioremediation, wastewater management, etc. *Galdieria* is certainly worth the effort to research it for future uses.
