Polar lipids and fatty acid composition of Thermus strains from New Zealand

PGLN: A newly identified amino phosphoglycolipid species in Thermus thermophilus HB8

Thermus thermophilus has several minor lipid molecules with structures that have not been described yet. In this study, we identified a new lipid molecule in T. thermophilus HB8 with an amino group at the polar head, by detecting lipid spots with HPTLC and mass spectrometry. The structure of the lipid resembles an amino sugar phospholipid, except for the glucosamine that lacks an acetyl group. We named this amino phosphoglycolipid PGLN, and proposed its synthetic pathway from a precursor, phosphatidyl-glyceric alkylamine. The primary amine structure of PGLN may contribute to high temperature adaptation through electrostatic interactions between the head groups.

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No amino phospholipid has been identified in T. thermophilus HB8 so far.

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PGLN is discovered by detecting lipid spots with HPTLC and mass spectrometry.

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PGLN is a newly identified amino phosphoglycolipid without an acetyl group.

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PGLN may play an important role in high temperature adaptation.

Pectinatus brassicae sp. nov., a Gram-negative, anaerobic bacterium isolated from salty wastewater

A novel Gram-negative, non-spore-forming, strictly anaerobic, heterotrophic bacterium, strain TYT, was isolated from salty pickle wastewater. Cells were rod-shaped with comb-like flagella, slightly curved and very variable in length. Optimal growth occurred at 28 °C and pH 6.5. Cells were resistant to up to 50 g NaCl l−1. Strain TYT produced acid from glycerol, sucrose, glucose, fructose and mannitol. The main fermentation products from glucose were acetic and propionic acids. Tests for acid phosphatase and naphthol-AS-BI-phosphohydrolase activities were positive. The major fatty acids were C14 : 0 DMA (18.7 %), C15 : 0 (15.4 %), anteiso-C18 : 1 (15.2 %), C11 : 0 (13.3 %) and summed feature 5 (C17 : 1ω7c and/or C17 : 2) (11.0 %). The DNA G+C content was 35.9 mol%. 16S rRNA gene sequence-based phylogenetic analysis indicated that strain TYT represented a novel species of the genus Pectinatus (sequence similarity to other members of the genus ranged from 93.2 to 94.8 %). Based on its phenotypic, genotypic and phylogenetic characteristics, strain TYT is proposed to represent a novel species, named Pectinatus brassicae sp. nov. (type strain TYT  = JCM 17499T  = DSM 24661T).

Thermus arciformis sp. nov., a thermophilic species from a geothermal area

Two aerobic, Gram-negative, non-motile, non-sporulating, yellow-pigmented bacteria, strains TH92(T) and TH91, were isolated from a hot spring located in Laibin, Guangxi, in the south-eastern geothermal area of China. The isolates grew at 40-77 degrees C (optimally at 70 degrees C) and at pH 6.0-9.5 (optimally at pH 7.5-8.0). Phylogenetic analysis of 16S rRNA gene sequences and levels of DNA-DNA relatedness together indicated that the new isolates represented a novel species of the genus Thermus with closest affinity to Thermus aquaticus, Thermus igniterrae and Thermus thermophilus. Compared with their closest relatives, strains TH92( T) and TH91 were able to assimilate a wider range of carbohydrates, amino acids and organic acids as sole carbon sources for growth, such as lactose and melibiose. The new isolates had lower combined levels of C(16 : 0 ) and iso-C(16 : 0) compared with their closest relatives. On the basis of polyphasic taxonomic characterization, strains TH92(T) and TH91 are considered to represent a single novel species of the genus Thermus, for which the name Thermus arciformis sp. nov. is proposed. The type strain is TH92(T) (=CGMCC 1.6992(T) =JCM 15153(T)).

Structural elucidation of phosphoglycolipids from strains of the bacterial thermophiles Thermus and Meiothermus

The structures of two major phosphoglycolipids from the thermophilic bacteria Thermus oshimai NTU-063, Thermus thermophilus NTU-077, Meiothermus ruber NTU-124, and Meiothermus taiwanensis NTU-220 were determined using spectroscopic and chemical analyses to be 2'-O-(1,2-diacyl-sn-glycero-3-phospho) -3'-O-(alpha-N-acetyl-glucosaminyl)-N-glyceroyl alkylamine [PGL1 (1)] and the novel structure 2'-O-(2-acylalkyldio-1-O-phospho)-3'-O-(alpha-N-acetylglucosaminyl)-N-glyceroyl alkylamine [PGL2 (2)]. PGL2 (2) is the first phosphoglycolipid identified with a 2-acylalkyldio-1-O-phosphate moiety. The fatty acids of the phosphoglycolipids are mainly iso-C(15:0), -C(16:0), and -C(17:0) and anteiso-C(15:0) and -C(17:0). The ratios of PGL2 (2) to PGL1 (1) are significantly altered when grown at different temperatures for three strains, T. thermophilus NTU-077, M. ruber NTU-124, and M. taiwanensis NTU-220, but not for T. oshimai NTU-063. Accordingly, the ratios of iso- to anteiso-branched fatty acids increase when grown at the higher temperature.

Structural determination of the polar glycoglycerolipids from thermophilic bacteria Meiothermus taiwanensis

The polar glycolipids were isolated from the thermophilic bacteria Meiothermus taiwanensis ATCC BAA-400 by ethanol extraction and purified by Sephadex LH-20 and silica gel column chromatography. The fatty acid composition of O-acyl groups in the glycolipids was obtained by gas chromatography mass spectroscopy analysis on their methyl esters derived from methanolysis and was made mainly of C(15:0) (34.0%) and C(17:0) (42.3%) fatty acids, with the majority as branched fatty acids (over 80%). Removal of O-acyl groups under mild basic conditions provided two glycolipids, which differ only in N-acyl substitution on a hexosamine. Electrospray mass spectroscopy analysis revealed that one has a C(17:0) N-acyl group and the other hydroxy C(17:0) in a ratio of about 1 : 3.5. Furthermore, complete de-lipidation with strong base followed by selective N-acetylation resulted in a homogeneous tetraglycosyl glycerol. The linkages and configurations of the carbohydrate moiety were then elucidated by MS and various NMR analyses. Thus, the major glycolipid from M. taiwanensis ATCC BAA-400 was determined with the following structure: alpha-Galp(1-6)-beta-Galp(1-6)-beta-GalNAcyl(1,2)-alpha-Glc(1,1)-Gro diester, where N-acyl is C(17:0) or hydroxy C(17:0) fatty acid and the glycerol esters were mainly iso- and anteisobranched C(15:0) and C(17:0).

F-and V-ATPases in the genus Thermus and related species

The discovery of a V-type ATPase in the gram-negative bacterium Thermus thermophilus HB8 (YOKOYAMA et al., J. Biol. Chem. 265, 21946, 1990) was unexpected, since only eukaryotic endomembranes and archaea were thought to contain this enzyme complex, and horizontal gene transfer was suggested to explain the finding. We examined membrane-associated ATPases from representatives of several groups of the genus Thermus. The enzymes were extracted with chloroform and purified by ion exchange chromatography or native gel electrophoresis. One novel Islandic isolate, T. scotoductus SE-1, as well as strain T. filiformis from New Zealand, possessed F-ATPases, as judged by the typical five subunit composition of the F1-moiety, sensitivity to azide, insensitivity to nitrate and a strong crossreaction with antibodies against the F1-ATPase from E. coli. In addition, N-terminal amino acid sequencing of the beta subunit from T. scotoductus SE-1 confirmed its homology with beta subunits from known F-ATPases. In contrast, the same extraction procedure released a V-ATPase from the membranes of T. thermophilus HB27 and T. aquaticus YT-1. The related species Meiothermus (formerly Thermus) chliarophilus ALT-8 also possessed a V-ATPase. All V-ATPases examined in this study contained larger major subunits than F-ATPases, crossreacted with antiserum against subunit A of the V-ATPase from the archaeon Halobacterium saccharovorum, and the N-terminal sequences of their major subunits were homologous to those of other V-ATPases. Sequences of the 16S rRNA gene clearly placed T. scotoductus SE-1, along with other non-pigmented Thermus strains, as a distinct species close to T. aquaticus. Our results suggested that at least two members of the genus, T. scotoductus SE-1 and T. filiformis, contain an F-ATPase, whereas several others possess a V-ATPase. These data could indicate a greater diversity of the genus Thermus than was previously thought. Alternatively, the genus may consist of species where horizontal gene transfer has occurred and others, where it has not.

Determination of the structure of a novel glycolipid from Thermus aquaticus 15004 and demonstration that hydroxy fatty acids are amide linked to glycolipids in Thermus spp

The compositions of the major glycolipids (GL-1) of five strains of Thermus aquaticus, the type strain of T. filiformis, T. oshimai SPS-11, and Thermnus sp. strain CG-2 were examined by gas chromatography, gas chromatography-mass spectroscopy, fast atom bombardment-mass spectroscopy, and chemical methods. The results showed that, with the exception of T. aquaticus 15004, the organisms each have a major glycolipid whose structure was established as diglycosyl-(N-acyl)glycosaminyl-glycosyl diacylglycerol. Glucosamine was present in GL-1 of T. oshimai SPS-11 and Thermus sp. strain CG-2, while galactosamine was present in the GL-1 of T. aquaticus and T. filiformis. The novel major glycolipid of T. aquaticus 15004 was identified as galactofuranosyl-(N-acetyl)galactosaminyl-(N-acyl)galactosaminyl-gluc - osyl diacylglycerol. The hydroxy fatty acids found in the T. aquaticus strains and in the type strain of T. filiformis were exclusively amide linked to the galactosamine of the major glycolipid. Ester-linked hydroxy fatty acids were not detected in the diacylglycerol moiety of GL-1 of these organisms. Hydroxy fatty acids were detected neither in the major glycolipid of T. oshimai SPS-11 and Thermnus sp. strain CG-2, in which glucosamine is present, nor in the major phospholipid of any of the strains examined.

DNA:DNA hybridization and chemotaxonomic studies of Thermus scotoductus

The species Thermus scotoductus was recently described as containing several non-pigmented isolates from Selfoss, Iceland, and the X-1 strain from the USA (Kristjansson et al., 1994). In this study, we performed DNA:DNA hybridizations and chemotaxonomic studies on several non-pigmented Thermus isolates from other geographical areas to assess their relationship to the strains originally assigned to this species. The results of DNA:DNA hybridizations showed that strains NH and Dl from London and strains Vl-7a and Vl-13 from Vizela, Portugal, belonged to T. scotoductus. T. scotoductus X-1 (ATCC 27978) was composed of two stable colony types, one of which had a major glycolipid different from the one present in the other colony type and from all other Thermus strains examined as well. The fatty acid composition of the isolates from Selfoss and London were practically identical. However, the fatty acid composition of strain X-1, the individual colony types of this strain and the Vizela strains were different from the Selfoss-London isolates and from each other. Another non-pigmented strain, designated SPS-11, belonged to a different DNA homology group.