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 29-O-(1,2-diacyl-sn-glycero-3-phospho) -39-O-(a-N-acetyl-glucosaminyl)-N-glyceroyl alkylamine [PGL1 (1)] and the novel structure (2) is the first phosphoglycolipid identified with a 2-acylalkyldio-1-Ophosphate 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. Supplementary key words nuclear magnetic resonance spectroscopy . matrix-assisted laser desorption ionization mass spectroscopy . capillary electrophoresis-mass spectroscopy . tandem mass spectrometry . Thermus oshimai NTU-063 . Thermus thermophilus NTU-077 . Meiothermus ruber NTU-124 . Meiothermus taiwanensis NTU-220Bacteria have evolved interesting thermoadaptive mechanisms, including changes in their membranes (1). For example, when Escherichia coli, Thermus aquaticus, Candida species, thermophilic Bacillus species, and Staphylococcus aureus are grown at high temperatures, the proportion of branched-chain fatty acids increases and the proportions of monoenoic and heptanoic fatty acids decrease (2). Temperature affects both the chain length and the degree of saturation of fatty acid components in Synechococcus species (3, 4). Polar lipid fatty acids can be used as a biochemical marker because many of the lipids of thermophilic bacteria isolated from microbial mats in hot springs have unique diol, plasmalogen, monoether, and diether structures (5).Thermus and Meiothermus species are Gram-negative thermophilic rods isolated from thermal hot springs, industrial and domestic water traps, and hydrothermal vents with neutral to alkaline pH (6). In these species, polar lipids occupy a large proportion of the cellular membrane fractions and usually include a major phospholipid, a major glycolipid, and minor phospholipids and glycolipids (7,8). The glycolipids usually contain three hexoses, one N-hexosamine, and one glycerol (6, 9-13). The hydrophobic parts are predominantly iso-and anteiso-branched fatty acids; straight-chain fatty acids are minor components. The high proportion of glycolipids in the cell membranes could possibly contribute to the ability of the bacteria to grow at high temperatures, because the relative proportions of the major glycolipids increase concomitantly with the growth temperature (14, 15).Thermus and Meiothermus species have been reported to have phosphoglycolipids (16) Abbreviations: CE-MS, capillary electrophoresis-mass spectroscopy; DQF-COSY, double quantum filtered-c...

Bacterial polysaccharides are known to induce the immune response in macrophages. Here we isolated a novel extracellular polysaccharide from the biofilm of Thermus aquaticus YT-1 and evaluated its structure and immunomodulatory effects. The size of this polysaccharide, TA-1, was deduced by size-exclusion chromatography as 500 kDa. GC-MS, high performance anionexchange chromatography with pulsed amperometric detection, electrospray ionization-MS/MS, and NMR revealed the novel structure of TA-1. The polysaccharide is composed of tetrasaccharide-repeating units of galactofuranose, galactopyranose, and N-acetylgalactosamine (1:1:2) and lacked acidic sugars. TA-1 stimulated macrophage cells to produce the cytokines TNF-␣ and IL-6. Screening of Toll-like receptors and antibodyblocking experiments indicated that the natural receptor of TA-1 in its immunoactivity is TLR2. Recognition of TA-1 by TLR2 was confirmed by TA-1 induction of IL-6 production in peritoneal macrophages from wild-type mice but not from TLR2 ؊/؊ mice. TA-1, as a TLR2 agonist, could possibly be used as an adjuvant and could enhance cytokine release, which increases the immune response. Furthermore, TA-1 induced cytokine release is dependent on MyD88/TIRAP.The excessive use of antibiotics poses tremendous selection pressure on microorganisms to develop drug resistance, which eventually leads to incurable diseases. Recent alternatives to antibiotics are immunomodulators. Instead of combating pathological microbes directly, the immunomodulators act to enhance the host defense responses without the development of drug resistance.Natural products extracted from microorganisms, mushrooms, algae, lichens, and higher plants were known to induce positive immunological effects and have been frequently used in the ancient practice of Chinese medicine (1). The mechanisms of action of these substances are often unknown, but polysaccharides in these extracts have been found to be the primary factor for macrophage stimulation through induction of the immune system of Toll-like receptors (2, 3). These biopolymers often show advantages over the polysaccharides that are currently in use, especially in combating microbial infections (4). Consequently, modulation of the innate immune system significantly improves the host ability to respond to different pathogens and diseases.The innate immune system is the first line of host defense. It protects the host from a variety of pathogens based on a limited repertoire of germ line-encoded receptors called pattern recognition receptors (PRRs). 4 PRRs include members of the Toll-like receptor (TLR) family and nucleotide binding oligomerization domain-like receptors and retinoic acidinducible gene-I-like receptors, which recognize pathogenassociated molecules, such as microbial components, and then trigger the release of inflammatory cytokine and type I interferons for host defense (5-8). These PRRs are localized in distinct cellular compartments. TLR1, TLR2, TLR4, TLR5, and TLR6 are expressed on the cell surface, whereas TLR3, ...

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Meiothermus taiwanensis sp. nov., a novel filamentous, thermophilic species isolated in Taiwan

A fengycin synthetase gene, fenB, has been cloned and sequenced. The protein (FenB) encoded by this gene has a predicted molecular mass of 143.6 kDa. This protein was overexpressed in Escherichia coli and was purified to near homogeneity by affinity chromatography. Experimental results indicated that the recombinant FenB has a substrate specificity toward isoleucine with an optimum temperature of 25°C, an optimum pH of 4.5, a K m value of 922 M, and a turnover number of 236 s ؊1 . FenB also consists of a thioesterase domain, suggesting that this protein may be involved in the activation of the last amino acid of fengycin.