Caldicellulosiruptor owensensis sp. nov., an anaerobic, extremely thermophilic, xylanolytic bacterium

Abstract

An anaerobic, extremely thermophilic, xylanolytic, non-spore-forming bacterium was isolated from a sediment sample taken from Owens Lake, California, and designated strain OLT (T = type strain). Strain OLT had a Gramnegative reaction and occurred as short rods which sometimes formed long chains containing a f e w coccoid cells. It grew a t 50-80 "C, with an optimum a t 75 "C. The pH range for growth was 55-900 with an optimum a t about pH 7.5. When grown on glucose a t optimal conditions, its doubling time was 7-3 h. In addition to glucose, the isolate utilized sucrose, xylose, fructose, ribose, xylan, starch, pectin and cellulose. Yeast extract stimulated growth on carbohydrates but was not obligately required. The end products from glucose fermentation were lactate, acetate, ethanol, H, and CO, . The G+C content of strain OLT was 36.6 mol%. The 165 rDNA sequence analysis indicated that strain OLT was a member of the subdivision containing Gram-positive bacteria with DNA G+C content of less than 55 mol% and clustered with members of the genus Caldicellulosiru~ tor. Because s tra i n OLT is p h y log ene t ica I I y and p he no typ ica I I y different from other members of this genus, it is proposed to designate this isolate Caldicellulosiruptor owensensis sp. nov. Strain OLT is the type strain (= ATCC 7001673.

Description of 'Synergistetes' phyl. nov. and emended description of the phylum 'Deferribacteres' and of the family Syntrophomonadaceae, phylum 'Firmicutes'

“…The members of the 'Synergistes' clade had a typical Gramnegative cell-wall structure with an outer membrane, as observed using electron microscopy (Allison et al, 1992;Baena et al, 1999Baena et al, , 2000Dahle & Birkeland, 2006;Magot et al, 1997;Menes & Muxi, 2002;Surkov et al, 2001;Zavarzina et al, 2000). In contrast, other members of Syntrophomonadaceae possessed a Gram-positive type cellwall structure without an outer membrane but with a thin peptidoglycan layer (Cayol et al, 1995;Gorlenko et al, 2004;Huang et al, 1998;Sokolova et al, 2002;Sekiguchi et al, 2000;Svetlitshnyi et al,1996;Takai et al, 1999). The thinness of this layer could explain the negative reaction to Gram stain observed for these bacteria.…”

Isolation, properties and kinetics of growth of a thermophilic Bacillus

“…The majority of the investigated thermophilic bacteria belong to the genus Bacillus and they have been isolated from thermophilic and mesophilic environments (3,4,8,11,13). According to Bergey's Manual of Systematic Bacteriology (5), this genus is phenotypically heterogeneous with members exhibiting an extremely wide range of nutritional requirements, growth conditions, metabolic diversity and DNA base composition (2).…”

“…Several intensive studies were performed to isolate thermophilic carbohydrate-fermenting bacteria from several habitats, aiming the use of these microbes and their enzymes for biotechnological applications (1,5,6,8,12,20,22). The majority of the investigated thermophilic bacteria belong to the genus Bacillus and they have been isolated from thermophilic and mesophilic environments (3,4,8,11,13).…”

Caldicellulosiruptor kronotskyensis sp. nov. and Caldicellulosiruptor hydrothermalis sp. nov., two extremely thermophilic, cellulolytic, anaerobic bacteria from Kamchatka thermal springs

“…The group of thermophilic cellulolytic prokaryotes includes two aerobic species, Rhodothermus marinus and Acidothermus cellulolyticus, and numerous anaerobes of the genera Caldicellulosiruptor, Clostridium, Spirochaeta, Fervidobacterium and Thermotoga (reviewed by Bergquist et al, 1999). At the time of writing, the genus Caldicellulosiruptor comprised five species with validly published names: Caldicellulosiruptor saccharolyticus (Rainey et al, 1994), Caldicellulosiruptor lactoaceticus (Mladenovska et al, 1995), Caldicellulosiruptor owensensis (Huang et al, 1998), Caldicellulosiruptor kristjanssonii (Bredholt et al, 1999) and Caldicellulosiruptor acetigenus (Onyenwoke et al, 2006). All members of the genus Caldicellulosiruptor are extremely thermophilic, cellulolytic, non-spore-forming anaerobes with Gram-positive type cell wall, and are capable of fermenting a wide spectrum of carbohydrates.…”

“…Temperature range for growth is 45-82 uC, with optimum growth at 70 uC; pH range for growth is 6.0-8.0, with optimum growth at pH 7.0. Rainey et al, 1994); 2, Caldicellulosiruptor lactoaceticus (Mladenovska et al, 1995); 3, Caldicellulosiruptor owensensis (Huang et al, 1998); 4, Caldicellulosiruptor kristjanssonii (Bredholt et al, 1999); 5, Caldicellulosiruptor acetigenus (Onyenwoke et al, 2006); 6, strain 2002 T (Caldicellulosiruptor kronotskyensis sp. nov.); 7, strain 108 T (Caldicellulosiruptor hydrothermalis sp.…”