Thermosipho globiformans sp. nov., an anaerobic thermophilic bacterium that transforms into multicellular spheroids with a defect in peptidoglycan formation

Abstract

An anaerobic rod-shaped thermophile was isolated from a hydrothermal vent at Suiyo Seamount, Izu-Bonin Arc, western Pacific Ocean, and was named strain MN14 T. The rods were Gram-negative-staining, non-motile without flagella, 2-4 mm long and 0.5 mm wide, and divided by binary fission in the mid-exponential phase. The cells were surrounded by a sheath-like structure (toga) and occurred singly or in chains. Spheroids containing multiple cells were observed not only in the stationary phase, as previously observed for species of the order Thermotogales, but also from the early exponential phase. Transmission electron microscopy revealed that the peptidoglycan in rods partly disintegrated in the early growth phases and that the outer membrane of the spheroids was not completely lined with peptidoglycan. These findings suggested that the spheroids were formed from rods by the disintegration of peptidoglycan and subsequent inflation of the outer membrane. The spheroids eventually generated tiny cells in the periplasmic space, indicating a viviparous mode of proliferation in addition to binary fission. Strain MN14 T grew at 40-75 6C, pH 5.0-8.2 and with 0.25-5.20 % (w/v) NaCl, with optimal growth occurring at 68 6C, pH 6.8 and with 2.5 % NaCl. The shortest doubling time was 24 min, assuming that the strain propagated only by binary fission. Elemental sulfur enhanced growth, but was not essential. Thiosulfate was not an electron acceptor for growth. The strain was a chemo-organotroph that grew on yeast extract as the sole growth substrate. Tryptone and starch supported its growth in the presence of yeast extract. The G+C content of the genomic DNA was 31.7 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that this strain belonged to the genus Thermosipho. No significant DNA-DNA hybridization was observed between the genomic DNA of strain MN14 T and phylogenetically related species of the genus Thermosipho. Based on this evidence, strain MN14 T is proposed to represent a novel species, named Thermosipho globiformans sp. nov. The species epithet globiformans reflects the formation of multicellular and reproductive spheroids by the novel strain. The type strain of this species is MN14 T (5JCM 15059 T 5DSM 19918 T).

Thermosipho activus sp. nov., a thermophilic, anaerobic, hydrolytic bacterium isolated from a deep-sea sample

“…All strains are characterized by: tendency to form chains; common sheath surrounding cells; ability to ferment yeast extract; inability to utilize acetate, ethanol, mannitol (for taxa 2, the ability to grow on these substrates was not determined); reduction of elemental sulphur to H 2 S and inability to reduce sulphate; and production of hydrogen and acetate during fermentation (for taxa 9, fermentation products were not determined (Tugel et al, 1986). Previously, among representatives of the genus Thermosipho, iron reduction was demonstrated for 'Thermosipho ferriphilus', Thermosipho melanesiensis and Thermosipho globiformans (Kendall, 2002;Kuwabara et al, 2011). Moreover, we have observed the same iron-reducing activity for Thermosipho affectus with yeast extract or tryptone but not acetate, lactate, pyruvate (20 mM) or H 2 (100 % gas phase) (data from this study).…”

“…The presence of elemental sulphur (5 g l 21 ), sulphate, thiosulphate, selenate or nitrate as 10 mM sodium salts did not influence the growth of the novel isolate, while sulphite and Strains: 1, Thermosipho activus sp. nov. Rift-s3 T (data from this study); 2, 'Thermosipho ferriphilus' GB 21 (Kendall, 2002); 3, Thermosipho atlanticus DV1140 T (Urios et al, 2004); 4, Thermosipho africanus Ob7 T (Huber et al, 1989;Ravot et al, 1996); 5, Thermosipho geolei SL31 T (L'Haridon et al, 2001); 6, Thermosipho japonicus IHB1 T (Takai & Horikoshi, 2000); 7, Thermosipho melanesiensis BI429 T (Antoine et al, 1997); 8, Thermosipho affectus ik275mar T (Podosokorskaya et al, 2011); 9, Thermosipho globiformans MN14 T (Kuwabara et al, 2011). All strains are characterized by: tendency to form chains; common sheath surrounding cells; ability to ferment yeast extract; inability to utilize acetate, ethanol, mannitol (for taxa 2, the ability to grow on these substrates was not determined); reduction of elemental sulphur to H 2 S and inability to reduce sulphate; and production of hydrogen and acetate during fermentation (for taxa 9, fermentation products were not determined (Tugel et al, 1986).…”

Anaerobic Coculture of Microalgae with Thermosipho globiformans and Methanocaldococcus jannaschii at 68°C Enhances Generation of n -Alkane-Rich Biofuels after Pyrolysis

“…T was isolated from a hydrothermal vent at Suiyo Seamount, Izu-Bonin Arc, western Pacific Ocean (28°34=N, 140°38=E), at a depth of 1,384 m and a temperature of 230°C and was identified in our laboratory (7) (22), 3 g of yeast extract (Difco), 3 g of tryptone (Difco), and 1 mg of resazurin. Sulfur powder was omitted from the Tc medium (7).…”

“…Sulfur powder was omitted from the Tc medium (7). After adjusting the pH to 6.5, the medium was sterilized by autoclaving and stored at room temperature.…”

“…On the other hand, Kuwabara et al (7) isolated a thermostable, anaerobic bacterium (Thermosipho globiformans) from a hydrothermal vent at Suiyou Seamount in the Western Pacific Ocean. The growth of this bacterium at 68°C under anaerobic conditions was enhanced 5-to 7-fold in coculture with the thermostable archaeon Methanocaldococcus jannaschii (8,9) compared with monoculture.…”