The Five Different Faces of the Diatoms

Diatoms are one of the most important groups of photosynthetic microorganisms ubiquitous in all aquatic ecosystems. These inconspicuous organisms have achieved spectacular ecological success and furthermore, are used as model organisms in scientific research in the field of biochemistry and genetics. Their ecological success is provided by their ability to tolerance and fast acclimation to rapid changing environmental conditions. Ecological significance and the ease of culture facilitate investigation and attempts of explanation the mechanisms of processes occurring in these organisms on the physiological, biochemical and genetic level. This review describes a number of our investigation strategies and techniques to understand the phenomenon of these organisms. We focused on five important aspects of diatoms biology, presented here as the five different faces of these algae. Acclimation mechanisms to environmental factors (temperature, light, heavy metals, age of the culture), on physiological and biochemical level at short and long time exposition of diatoms, are presented as the first diatoms face. The second face presents diatoms as organisms useful for phytoremediation. The results of the molecular analyses of the selected enzymes involved in photoprotective mechanisms of diatoms is the third face of these algae. The significance of diatoms as a treasury of bioactive compounds (xanthophylls and long chain polyunsaturated fatty acids) important in human diet, is displayed as the fourth face. Finally, as the only one which has not been investigated in our laboratory, we describe the fifth face of diatoms – the rich source of biofuels. In our research we used two model diatoms species: Phaeodactylum tricornutum and Thalassiosira pseudonana.