Polysaccharide Degradation and Synthesis by Extremely Thermophilic Anaerobes

Extremely thermophilic fermentative anaerobes (growth Topt ≥ 70°C) have the capacity to use a variety of carbohydrates as carbon and energy sources. As such, a wide variety of glycoside hydrolases and transferases have been identified in these microorganisms. The genomes of three model extreme thermophiles—an archaeon Pyrococcus furiosus (Topt = 98°C), and two bacteria, Thermotoga maritima (Topt = 80°C) and Caldicellulosiruptor saccharolyticus (Topt = 70°C)—encode numerous carbohydrate‐active enzymes, many of which have been characterized biochemically in their native or recombinant forms. In addition to their voracious appetite for polysaccharide degradation, polysaccharide production has also been noted for extremely thermophilic fermentative anaerobes; T. maritima generates exopolysaccharides that aid in biofilm formation, a process that appears to be driven by intraspecies and interspecies interactions.