Microbial Genome Sequencing: Genome Analysis of Galdieria sulphuraria - A Unique Unicellular Thermo-Acidophilic Photosynthetic Microorganism

Michigan State University, East Lansing MI

Investigators

Abstract

Extreme environments are frequently inhabited by extremophiles, which are almost always prokaryotic organisms. However, the red micro-alga Galdieria sulphuraria (Cyanidiales) is a eukaryote that can represent up to 90% of the biomass in extreme habitats such as hot sulfur springs (pH 0.05 to 4; temperatures up to 56 degrees C). The gene sequences of this living fossil should reveal much about the evolution of modern eukaryotes. Galdieria thrives on more than 50 different carbon sources, including a number of rare sugars and sugar alcohols - evidence of a large repertoire of metabolic genes equaled by few other organisms and a potentially rich source of thermo-stable enzymes for biotechnology. Moreover, this organism tolerates toxic metal ions such as cadmium, mercury, aluminum or nickel, suggesting potential use in bioremediation. Proteins isolated from thermophiles frequently crystallize more readily, making Galdieria proteins valuable for structural biology studies. Finally, the high temperatures under which Galdieria photosynthesizes are at the extreme ranges for this process; thus this organism will likely prove a useful model for physical studies on the photosynthetic apparatus. The genome of Galdieria sulphuraria will be sequenced. Sequences will be collated and annotated, provided to public databases, and specialized databases for the exploitation of this data will be developed. This research will generate a wealth of knowledge on the adaptation of eukaryotic organisms to extreme environments, on molecular mechanisms of protein thermo-stability, and on the coordination of gene regulation in adaptation of metabolic pathways to extreme stress. In addition, the project will add to the understanding of genome evolution, and the phylogeny of plants and plastids.