ABSTRACT
The complete genome sequence of the thermoacidophilic archaeon Metallosphaera sedula (DSM 5348) is reported here. M. sedula, originally isolated from a volcanic field in Italy, is a prolific iron-oxidizing archaeon with applications in bioleaching of sulfide minerals.
ABSTRACT
The complete genome sequence of the extremely thermophilic bacterium Anaerocellum (f. Caldicellulosiruptor) danielii (DSM:8977) is reported here. A. danielii is a fermentative anaerobe and capable of lignocellulose degradation with potential applications in biomass degradation and production of chemicals and fuels from renewable feedstocks.
ABSTRACT
Reported here is the complete genome sequence (2,191,724 bp) for the thermoacidophilic archaeon Sulfuracidifex (f. Sulfolobus) metallicus DSM 6482 (Topt 65°C, pHopt 2.0). This obligately chemolithoautotrophic microorganism is a prolific metal and sulfur oxidizer and has application in metal bioleaching operations. A multi-assembly reconciliation approach enabled closure of the genome.
ABSTRACT
Caldicellulosiruptor species are proficient at solubilizing carbohydrates in lignocellulosic biomass through surface (S)-layer bound and secretomic glycoside hydrolases. Tapirins, surface-associated, non-catalytic binding proteins in Caldicellulosiruptor species, bind tightly to microcrystalline cellulose, and likely play a key role in natural environments for scavenging scarce carbohydrates in hot springs. However, the question arises: If tapirin concentration on Caldicellulosiruptor cell walls increased above native levels, would this offer any benefit to lignocellulose carbohydrate hydrolysis and, hence, biomass solubilization? This question was addressed by engineering the genes for tight-binding, non-native tapirins into C. bescii. The engineered C. bescii strains bound more tightly to microcrystalline cellulose (Avicel) and biomass compared to the parent. However, tapirin overexpression did not significantly improve solubilization or conversion for wheat straw or sugarcane bagasse. When incubated with poplar, the tapirin-engineered strains increased solubilization by 10% compared to the parent, and corresponding acetate production, a measure of carbohydrate fermentation intensity, was 28% higher for the Calkr_0826 expression strain and 18.5% higher for the Calhy_0908 expression strain. These results show that enhanced binding to the substrate, beyond the native capability, did not improve C. bescii solubilization of plant biomass, but in some cases may improve conversion of released lignocellulose carbohydrates to fermentation products.
Subject(s)
Cellulose , Saccharum , Cellulose/metabolism , Biomass , Saccharum/metabolism , Caldicellulosiruptor/metabolism , Clostridiales/metabolism , Plants , Archaea/metabolismABSTRACT
Reported here are complete genome sequences for two anaerobic, thermophilic bacteria isolated from wheat straw, i.e., the (hemi)cellulolytic Thermoclostridium stercorarium subspecies strain RKWS1 (3,029,933 bp) and the hemicellulolytic Thermoanaerobacter species strain RKWS2 (2,827,640 bp). Discovery of indigenous thermophiles in plant biomass suggests that high-temperature microorganisms are more ubiquitous than previously thought.
ABSTRACT
The genome sequences of three extremely thermophilic, lignocellulolytic Caldicellulosiruptor species were closed, improving previously reported multiple-contig assemblies. All 14 classified Caldicellulosiruptor spp. now have closed genomes. Genome closure will enhance bioinformatic analysis of the species, including identification of carbohydrate-active enzymes (CAZymes) and comparison against other Caldicellulosiruptor species and lignocellulolytic microorganisms.
