Quantitative 31P NMR Method for Individual and Concomitant Determination of Phospholipid Classes in Polar Lipid Samples.

Herein, to achieve individual and concomitant quantifications of phospholipid classes, an absolute quantification 31P NMR method using an internal standard was examined. Phospholipid standards and dietary foods were dispersed to prepare test solutions in an anionic surfactant (sodium cholate) solution containing EDTA, as a modification based on a reported method. Each phospholipid class showed a reproducible chemical shift at a near-neutral test solution pH of 6.90±0.04 and temperature of 30.0±0.1°C. The quantity of synthetic phosphatidylcholine measured using 31P NMR was consistent with that measured by 1H NMR using an internal standard. As the principal phospholipid class of soybean and egg yolk lecithin is phosphatidylcholine, the measurement conditions of 31P NMR (pulse interval time and number of scans) were optimized such that minor phospholipids, including lysophospholipids, also present in lecithin could be quantified simultaneously. Phospholipid classes in commercial polar lipid samples derived from porcine brain, yeast, and soybean were individually quantified using the above conditions. Using phosphoserine as the internal standard material allowed the absolute molar quantity of the phospholipid class to be precisely determined with traceability to the SI. The determined molar amounts of phospholipid classes were then translated to the weight amount by assuming that each phospholipid class contained two stearic acid molecules as the constituent fatty acid. The calculated total contents of each phospholipid class by 31P NMR were in good agreement with those obtained by molybdenum blue colorimetry. Furthermore, the quantitative values of the principal phospholipid classes in the polar lipid samples obtained by 31P NMR corresponded in a broad view, however, was more informative for the separation of individual phospholipid species rather than the quantitative 2D thin-layer chromatography.

Degradation of carbonyl sulfide by Actinomycetes and detection of clade D of ß-class carbonic anhydrase.

Carbonyl sulfide (COS) is an atmospheric trace gas and one of the sources of stratospheric aerosol contributing to climate change. Although one of the major sinks of COS is soil, the distribution of COS degradation ability among bacteria remains unclear. Seventeen out of 20 named bacteria belonging to Actinomycetales had COS degradation activity at mole fractions of 30 parts per million by volume (ppmv) COS. Dietzia maris NBRC 15801T and Mycobacterium sp. THI405 had the activity comparable to a chemolithoautotroph Thiobacillus thioparus THI115 that degrade COS by COS hydrolase for energy production. Among 12 bacteria manifesting rapid degradation at 30 ppmv COS, D. maris NBRC 15801T and Streptomyces ambofaciens NBRC 12836T degraded ambient COS (∼500 parts per trillion by volume). Geodermatophilus obscurus NBRC 13315T and Amycolatopsis orientalis NBRC 12806T increased COS concentrations. Moreover, six of eight COS-degrading bacteria isolated from soils had partial nucleotide sequences similar to that of the gene encoding clade D of ß-class carbonic anhydrase, which included COS hydrolase. These results indicate the potential importance of Actinomycetes in the role of soils as sinks of atmospheric COS.