Complete Genome Sequences for the Anaerobic, Extremely Thermophilic Plant Biomass-Degrading Bacteria Caldicellulosiruptor hydrothermalis , Caldicellulosiruptor kristjanssonii , Caldicellulosiruptor kronotskyensis , Caldicellulosiruptor owensensis , and Caldicellulosiruptor lactoaceticus

Abstract

The genus Caldicellulosiruptor contains the most thermophilic, plant biomass-degrading bacteria isolated to date. Previously, genome sequences from three cellulolytic members of this genus were reported (C. saccharolyticus, C. bescii, and C. obsidiansis). To further explore the physiological and biochemical basis for polysaccharide degradation within this genus, five additional genomes were sequenced: C. hydrothermalis, C. kristjanssonii, C. kronotskyensis, C. lactoaceticus, and C. owensensis. Taken together, the seven completed and one draft-phase Caldicellulosiruptor genomes suggest that, while central metabolism is highly conserved, significant differences in glycoside hydrolase inventories and numbers of carbohydrate transporters exist, a finding which likely relates to variability observed in plant biomass degradation capacity.

Comparative Analysis of Extremely Thermophilic Caldicellulosiruptor Species Reveals Common and Unique Cellular Strategies for Plant Biomass Utilization

“…To date, Caldicellulosiruptor species have been isolated globally from terrestrial hot springs and thermal features in locations including the United States (C. owensensis [2,3] and C. obsidiansis [4,5]), Russia (C. bescii [6,7]), C. kronotskyensis [2,8], and C. hydrothermalis [2,8]), New Zealand (C. saccharolyticus [9-11]), and Iceland (C. kristjanssonii [2,12] and C. lactoaceticus [2,13]). Characteristic of Caldicellulosiruptor species are multidomain extracellular and S-layer-associated glycoside hydrolases (GHs) that mediate the microbial conversion of complex carbohydrates (14-16).…”

“…Characteristic of Caldicellulosiruptor species are multidomain extracellular and S-layer-associated glycoside hydrolases (GHs) that mediate the microbial conversion of complex carbohydrates (14)(15)(16). Sequenced genomes for Caldicellulosiruptor species (2,4,6,10) indicate that some, but not all, encode GH48-containing enzymes (17), and these appear to be essential for crystalline cellulose degradation (18). The cellulolytic Caldicellulosiruptor species also utilize novel binding proteins (ta pirins) to adhere to plant biomass (19).…”

Dissecting and engineering metabolic and regulatory networks of thermophilic bacteria for biofuel production

“…Comparison of eight Caldicellulosiruptor genomes revealed significant inter-genome differences in glycoside hydrolase inventories and the number of carbohydrate transporters, even though their central metabolism pathways are highly conserved, indicating varied capacity in plant biomass degradation among members of Caldicellulosiruptor (Blumer-Schuette et al, 2011). Intriguingly, C. bescii is not only able to degrade various polysaccharides and unprocessed plant biomass, but also capable of degrading cellulose and xylan simultaneously (Dam et al, 2011).…”

“…Intriguingly, C. bescii is not only able to degrade various polysaccharides and unprocessed plant biomass, but also capable of degrading cellulose and xylan simultaneously (Dam et al, 2011). Genomic, transcriptomic and proteomic analysis revealed its several features in polysaccharide degradation (Blumer-Schuette et al, 2011;Dam et al, 2011), which included multi-modular, multifunctional carbohydrate-active (CAZy) protein genes organized into one large functional gene cluster, high dosage of certain CAZymes mediated by gene duplication, and acquisition of CAZy genes and ABC transporters via lateral gene transfer (LGT). Furthermore, instead of employing the cellulosomes, C. bescii does not encode dockerins, and flexibly produces combinations of "free-acting" cellulases in response to various insoluble polysaccharides.…”

Multidomain, Surface Layer-associated Glycoside Hydrolases Contribute to Plant Polysaccharide Degradation by Caldicellulosiruptor Species

“…Currently, the genomes of 12 members of the genus have been sequenced, representing species isolated from globally distributed terrestrial hot springs (53)(54)(55)(56)(57). Caldicellulosiruptor species produce many extracellular CAZymes, including some that have SLH domains (58).…”