Affiliation:
1. BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
Abstract
ABSTRACT
A novel, obligately anaerobic, extremely thermophilic, cellulolytic bacterium, designated OB47
T
, was isolated from Obsidian Pool, Yellowstone National Park, WY. The isolate was a nonmotile, non-spore-forming, Gram-positive rod approximately 2 μm long by 0.2 μm wide and grew at temperatures between 55 and 85°C, with the optimum at 78°C. The pH range for growth was 6.0 to 8.0, with values of near 7.0 being optimal. Growth on cellobiose produced the fastest specific growth rate at 0.75 h
−1
. The organism also displayed fermentative growth on glucose, maltose, arabinose, fructose, starch, lactose, mannose, sucrose, galactose, xylose, arabinogalactan, Avicel, xylan, filter paper, processed cardboard, pectin, dilute acid-pretreated switchgrass, and
Populus
. OB47
T
was unable to grow on mannitol, fucose, lignin, Gelrite, acetate, glycerol, ribose, sorbitol, carboxymethylcellulose, and casein. Yeast extract stimulated growth, and thiosulfate, sulfate, nitrate, and sulfur were not reduced. Fermentation end products were mainly acetate, H
2
, and CO
2
, although lactate and ethanol were produced in 5-liter batch fermentations. The G+C content of the DNA was 35 mol%, and sequence analysis of the small subunit rRNA gene placed OB47
T
within the genus
Caldicellulosiruptor
. Based on its phylogenetic and phenotypic properties, the isolate is proposed to be designated
Caldicellulosiruptor obsidiansis
sp. nov. and OB47 is the type strain (ATCC BAA-2073).
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology