Fractionation and purification of membrane lipids from the archaeon Thermoplasma acidophilum DSM 1728/10217

Screening and Characterization of Two Extracellular Polysaccharide-Producing Bacteria from the Biocrust of the Mu Us Desert

The extracellular polysaccharide (EPS) matrix embedding microbial cells and soil particles plays an important role in the development of biological soil crusts (BSCs), which is widely recognized as beneficial to soil fertility in dryland worldwide. This study examined the EPS-producing bacterial strains YL24-1 and YL24-3 isolated from sandy soil in the Mu Us Desert in Yulin, Shaanxi province, China. The strains YL24-1 and YL24-3 were able to efficiently produce EPS; the levels of EPS were determined to be 257.22 μg/mL and 83.41 μg/mL in cultures grown for 72 h and were identified as Sinorhizobium meliloti and Pedobacter sp., respectively. When the strain YL24-3 was compared to Pedobacter yulinensis YL28-9^T using 16S rRNA gene sequencing, the resemblance was 98.6% and the strain was classified as Pedobacter sp. using physiological and biochemical analysis. Furthermore, strain YL24-3 was also identified as a subspecies of Pedobacter yulinensis YL28-9^T on the basis of DNA–DNA hybridization and polar lipid analysis compared with YL28-9^T. On the basis of the EPS-related genes of relevant strains in the GenBank, several EPS-related genes were cloned and sequenced in the strain YL24-1, including those potentially involved in EPS synthesis, assembly, transport, and secretion. Given the differences of the strains in EPS production, it is possible that the differences in gene sequences result in variations in the enzyme/protein activities for EPS biosynthesis, assembly, transport, and secretion. The results provide preliminary evidence of various contributions of bacterial strains to the formation of EPS matrix in the Mu Us Desert.

The Main (Glyco) Phospholipid (MPL) of Thermoplasma acidophilum

The main phospholipid (MPL) of Thermoplasma acidophilum DSM 1728 was isolated, purified and physico-chemically characterized by differential scanning calorimetry (DSC)/differential thermal analysis (DTA) for its thermotropic behavior, alone and in mixtures with other lipids, cholesterol, hydrophobic peptides and pore-forming ionophores. Model membranes from MPL were investigated; black lipid membrane, Langmuir-Blodgett monolayer, and liposomes. Laboratory results were compared to computer simulation. MPL forms stable and resistant liposomes with highly proton-impermeable membrane and mixes at certain degree with common bilayer-forming lipids. Monomeric bacteriorhodopsin and ATP synthase from Micrococcus luteus were co-reconstituted and light-driven ATP synthesis measured. This review reports about almost four decades of research on Thermoplasma membrane and its MPL as well as transfer of this research to Thermoplasma species recently isolated from Indonesian volcanoes.

Molecular species determination of oligosaccharides and glycoconjugates in soybean lecithin powders

BACKGROUND

Oligosaccharides and glycoconjugates in soybean lecithin powder are very important for the properties and functions of the materials that contain it. Oligosaccharides can trigger infusion reactions and color changes in soybean lecithin during medical injections; glycoconjugates in the form of glycolipids can also change the physical behavior of lecithin. The molecular components of oligosaccharides and glycoconjugates in soybean lecithin powder were studied in this paper.

RESULTS

Three oligosaccharides and 21 glycoconjugates were verified in soybean lecithin powders for the first time. Raffinose, sucrose, and stachyose were detected as the principal components of oligosaccharides by high-performance liquid chromatography (HPLC). Twenty-one glycoconjugates, including four steryl glucosides (SG), 13 acyl steryl glucosides (ASG), one digalactosyl diacylglycerol (DGDG), one monogalactosyl diacylglyceride (MGDG), one glucocerebroside (Glucer), and one glucose palmitate were analyzed by gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS) and RP-UPLC-Q-TOF-ESI-MS. Glycoconjugates were constructed in soybean lecithin powder after separation by column chromatography, thin-layer chromatography, and color reactions.

CONCLUSION

The determination of molecular species of oligosaccharides and glycoconjugates provided a new direction for the exploration of novel functions and uses of soybean lecithin powder. © 2018 Society of Chemical Industry.

Stable archaeal tetraether lipid liposomes for photodynamic application: transfer of carboxyfluorescein to cultured T84 tumor cells

Background: Archaeal membranes have phytanyl ether lipids instead of common fatty acid-glycerol esters in bacterial and eukaryotic cells. Sulfolobus and Thermoplasma species have unique membrane-spanning tetraether lipids (TEL), which form stable liposomes. Recently, we cultured Thermoplasma species from the Indonesian volcano Tangkuban Perahu and isolated TEL. The purpose of this in vitro study is to investigate the transfer of fluorescent dye from stable TEL liposomes to cultured colon carcinoma cells.Methods: TEL was extracted from cultured cells with chloroform-methanol (1:1), then it was fractionated and purified via diethylaminoethyl-cellulose-acetate columns and activated charcoal for the formation of stable liposomes. For the fluorescence exchange assay, TEL liposomes were loaded with water-soluble carboxyfluorescein (CF). Staining experiments were conducted with various cell cultures, and T84 colon carcinoma cells were chosen for the main experiments. Liposome stability was tested by light scattering and electron microscopic size determinations as well as by unspecific CF release at low pH (6.0–7.4) and increased temperature  (4–50°C/70°C).Results: TEL liposomes exhibit high stability and extremely low proton permeability at low pH. CF staining of cultured T84 colon carcinoma cells appeares more intensive from TEL liposomes than from dipalmitoylphosphatidylcholine liposomes.Conclusion: The results of this in vitro study demonstrate CF staining of colon carcinoma cells and high stability of TEL liposomes at low pH, matching the condition in the gastro-intestinal (GI) route and in the urogentital (UG) tract. For this reason, in vivo studies on liposomal fluorescent photosensitizers for topical application of photodynamic cancer therapy in the GI and UG tracts should be carried out.