Microbial community structure and activity linked to contrasting biogeochemical gradients in bog and fen environments of the Glacial Lake Agassiz Peatland.

The abundances, compositions, and activities of microbial communities were investigated at bog and fen sites in the Glacial Lake Agassiz Peatland of northwestern Minnesota. These sites contrast in the reactivity of dissolved organic matter (DOM) and the presence or absence of groundwater inputs. Microbial community composition was characterized using pyrosequencing and clone library construction of phylogenetic marker genes. Microbial distribution patterns were linked to pH, concentrations of dissolved organic carbon and nitrogen, C/N ratios, optical properties of DOM, and activities of laccase and peroxidase enzymes. Both bacterial and archaeal richness and rRNA gene abundance were >2 times higher on average in the fen than in the bog, in agreement with a higher pH, labile DOM content, and enhanced enzyme activities in the fen. Fungi were equivalent to an average of 1.4% of total prokaryotes in gene abundance assayed by quantitative PCR. Results revealed statistically distinct spatial patterns between bacterial and fungal communities. Fungal distribution did not covary with pH and DOM optical properties and was vertically stratified, with a prevalence of Ascomycota and Basidiomycota near the surface and much higher representation of Zygomycota in the subsurface. In contrast, bacterial community composition largely varied between environments, with the bog dominated by Acidobacteria (61% of total sequences), while the Firmicutes (52%) dominated in the fen. Acetoclastic Methanosarcinales showed a much higher relative abundance in the bog, in contrast to the dominance of diverse hydrogenotrophic methanogens in the fen. This is the first quantitative and compositional analysis of three microbial domains in peatlands and demonstrates that the microbial abundance, diversity, and activity parallel with the pronounced differences in environmental variables between bog and fen sites.

Identification of copper binding sites in soil organic matter through chemical modifications and 13C CP-MAS NMR spectroscopy.

Metal binding to an organic peat soil was probed by paramagnetic doping with copper, chemical modifications of the organic matter in the soil, and 13C CP-MAS NMR spin lattice relaxation rate measurements. Carboxyl and hydroxyl functional groups were determined to be most significant in copper uptake by the unmodified soil. Esterification and acetylation of the soil showed that metal binding by carbohydrate structures occurs independently of other functional groups and may even induce a pseudochelation phenomenon. Sorption isotherms corroborate the importance of carbohydrate structures in metal binding. These results suggest that environmental modeling of metal binding and retention in soils should incorporate estimates of the distributions of all functional groups in the soil organic matter (e.g. aliphatic, carbohydrate, phenolic, carboxyl) and their relative binding strengths.

Plasma vitamin E concentrations of older infants fed cow's milk or infant formula.

Nutrition of older infants, though important for optimal brain development, is inadequately studied. The beverage choice markedly influences nutrient intake, but little is known regarding nutrition status of older infants, particularly for vitamin E. This study assessed vitamin E intakes and plasma tocopherol concentrations in two groups of healthy infants, 8 to 13 months of age, who had consumed either cow's milk (n = 45) or milk-based formula (n = 55) for a minimum of the 3 preceding months. Mean (+/- SEM) vitamin E intake was significantly lower (p < or = 0.001) by the infants who had consumed cow's milk (CMF) than by infants who had consumed formula (FF); 4.1 +/- 0.25 mg/day and 10.9 +/- 0.57 mg/day, respectively. Mean (+/- SEM) intake of linoleic plus linolenic acids was significantly lower (p < or = 0.005) by CMF infants (3.4 +/- 0.2 g) than by FF infants (9.9 +/- 1.0 g), although mean (+/- SEM) dietary vitamin E to polyunsaturated fat ratio (E/PUFA ratio) was the same in both FF and CMF infants (1.3 +/- 0.1). Plasma alpha-tocopherol concentration (mean +/- SD) was significantly lower (p < or = 0.005) in CMF than in FF infants (0.86 +/- 0.28 mg/dl vs. 1.14 +/- 0.42 mg/dl, respectively). Dietary vitamin E intakes were positively correlated (p < or = 0.05) with plasma alpha-tocopherol concentrations. No correlations were found between plasma alpha-tocopherol concentrations and total fat intake, dietary E/PUFA ratios, erythrocyte polyunsaturated fatty acids > or = C18:2, or number of hours postprandial that blood was drawn.(ABSTRACT TRUNCATED AT 250 WORDS)

Isocratic high-performance liquid chromatographic separation and multiple-wavelength ultraviolet detection of aldicarb and its soil degradation products. Optimization of stationary phase selectivity.

The unique selectivities which can be generated through optimization of stationary/mobile phase combinations have been applied to the development of an isocratic, reversed-phase high-performance liquid chromatographic method for the separation of aldicarb and its primary soil degradation products. The method utilizes a cyanopropyl bonded stationary phase and water-acetonitrile mobile phase and is capable of separating aldicarb and its various sulfoxide, sulfone and oxime derivatives in less than 10 min. When combined with multiple-wavelength UV detection and an appropriate preconcentration step, this method can in principle be applied to the routine monitoring of aldicarb and its soil derivatives in water at concentrations less than 1 microgram/l.

Solid-state 13C nuclear magnetic resonance spectroscopy of simultaneously metabolized acetate and phenol in a soil Pseudomonas sp.

We investigated concentration-dependent primary and secondary substrate relationships in the simultaneous metabolism of the ubiquitous pollutant phenol and the naturally occurring substrate acetate by a Pseudomonas sp. soil isolate capable of utilizing either substance as a sole source of carbon and energy. In addition to conventional analytical techniques, solid-state 13C nuclear magnetic resonance spectroscopy was used to follow the cellular distribution of [1-13C]acetate in the presence of unlabeled phenol. With 5 mM acetate as the primary substrate, Pseudomonas sp. 9S8D2 removed 1 mM phenol (secondary substrate) at a rate of 2 nmol/mg of total cell protein. Although extensive acetate metabolism was indicated by a significant redistribution of the carboxyl label, this redistribution was not affected by the presence of phenol as a secondary substrate. When the primary and secondary substrate roles were reversed, however, the presence of 1 mM phenol altered the metabolism of 0.1 mM acetate, as evidenced by both the two- to fourfold increases in carboxyl label that appeared in terminal methyl and acyl chain methylene carbon resonances and the decrease in label that occurred in the carbohydrate spectral region. These results suggest that, when phenol is present as the primary substrate, acetate is preferentially shuttled into fatty acyl chain synthesis, whereas phenol carbon is funnelled into the tricarboxylic acid cycle. Thus, simultaneous use of a xenobiotic compound and a natural substrate apparently does occur, and the relative concentrations of the two substrates do influence the rate and manner in which the compounds are utilized.(ABSTRACT TRUNCATED AT 250 WORDS)