Iron is one of the most microbiologically and chemically important metals in natural waters. The biogeochemical cycling of iron is significantly influenced by the redox cycling of Fe(II) and Fe(III). Because of the unique chemistry of iron, it is often needed to analyze iron at nano-molar concentrations. This article describes a reverse flow injection analysis (rFIA) based method with ferrozine spectrophotometric detection to quantify total iron concentration in stream water at nanomolar concentrations. The rFIA system has a 0.65 nM detection limit and a linear dynamic range up to 1.40 mu M for the total iron analysis. The detection limit was achieved using a 1.0 m long liquid waveguide capillary flow cell, 1.50 m long knotted reaction coil, 87.50 mu L. injection loop and a miniature fiber optics spectrophotometer. The optimized colorimetric reagent has 1.0 mM ferrozine, 0.1 M ascorbic acid, 1.0 mM citric acid and 0.10 M acetate buffer adjusted to pH 4.0. The best sample flow rate is 2.1 mL min(-1) providing a sample throughput of more than 15 samples h(-1). The linear dynamic range of the method can be adjusted by changing the volume of the injection loop. The rFIA manifold was assembled exclusively from commercially available components.

The composition of dissolved organic matter (DOM) in extremely deep groundwaters has rarely been investigated. Focusing on deep fracture waters in billion year old rocks in South Africa, we hypothesized the DOM would be predominantly derived from in situ microbial sources, consistent with H-2-driven lithoautotrophic ecosystems previously documented in these fluids. We collected groundwater from 0.6 to 3.4 km depths via boreholes in mines, and characterized the DOM by a variety of analytical methods. Dissolved organic carbon concentrations ranged from 0.25 to 4.9 mg C/L. Low molecular weight organic acids (formate, acetate, lactate, propanoate) and amino acids (after hydrolysis) accounted for varying fractions of the total dissolved organic carbon. UV spectrophotometry, scanning fluorimetry, and nuclear magnetic resonance (NMR) spectra indicated lower concentrations of aromatic compounds than are commonly found in surface waters and shallow groundwaters. Molecular weights of aromatic compounds measured by size-exclusion chromatography were dominantly 500-1000 Da. Scanning fluorimetry revealed humic substances in two shallow (578 and 1300 m) samples; deeper samples showed peaks indicating aromatic amino acids. Intensive study of one sample from a previously sampled borehole in Beatrix mine resulted in large NMR peaks for aliphatics and carboxyls with lesser aromatics peaks; negative electrospray ion Fourier transform ion cyclotron resonance-mass spectrometry detected protein-, lipid-, and lignin-like compounds. These results are consistent with DOM in the form of microbial metabolites, and modified cell components (membrane lipids and proteins). These findings support previous geomicrobiological reports of chemolithoautotrophic microbial ecosystems functioning in isolation from photosynthetic primary production. (C) 2018 Elsevier Ltd. All rights reserved.

Deep continental subsurface fracture water systems, ranging from 1.1 to 3.3 km below land surface (kmbls), were investigated to characterize the indigenous microorganisms and elucidate microbial carbon sources and their cycling. Analysis of phospholipid fatty acid (PLFA) abundances and direct cell counts detected varying biomass that was not correlated with depth. Compound-specific carbon isotope analyses (delta C-13 and Delta C-14) of the phospholipid fatty acids (PLFAs) and carbon substrates combined with genomic analyses did identify, however, distinct carbon sources and cycles between the two depth ranges studied.In the shallower boreholes at circa 1 kmbls, isotopic evidence indicated microbial incorporation of biogenic CH4 by the in situ microbial community. At the shallowest site, 1.05 kmbls in Driefontein mine, this process clearly dominated the isotopic signal. At slightly deeper depths, 1.34 kmbls in Beatrix mine, the isotopic data indicated the incorporation of both biogenic CH4 and dissolved inorganic carbon (DIC) derived from CH4 oxidation. In both of these cases, molecular genetic analysis indicated that methanogenic and methanotrophic organisms together comprised a small component (<5%) of the microbial community. Thus, it appears that a relatively minor component of the prokaryotic community is supporting a much larger overall bacterial community in these samples.In the samples collected from >3 kmbls in Tau Tona mine (TT107, TT109 Bh2), the CH4 had an isotopic signature suggesting a predominantly abiogenic origin with minor inputs from microbial methanogenesis. In these samples, the isotopic enrichments (delta C-13 and Delta C-14) of the PLFAs relative to CH4 were consistent with little incorporation of CH4 into the biomass. The most C-13-enriched PLFAs were observed in TT107 where the dominant CO2-fixation pathway was the acetyl-CoA pathway by non-acetogenic bacteria. The differences in the delta C-13 of the PLFAs and the DIC and DOC for TT109 Bh2 were similar to-24% and 0%, respectively. The dominant CO2-fixation pathways were 3-HP/4-HB cycle > acetyl-CoA pathway > reductive pentose phosphate cycle. (C) 2015 Elsevier Ltd. All rights reserved.

Comparative studies on community phylogenetics and phylogeography of microorganisms living in extreme environments are rare. Terrestrial subsurface habitats are valuable for studying microbial biogeographical patterns due to their isolation and the restricted dispersal mechanisms. Since the taxonomic identity of a microorganism does not always correspond well with its functional role in a particular community, the use of taxonomic assignments or patterns may give limited inference on how microbial functions are affected by historical, geographical and environmental factors. With seven metagenomic libraries generated from fracture water samples collected from five South African mines, this study was carried out to (1) screen for ubiquitous functions or pathways of biogeochemical cycling of CH4, S, and N; (2) to characterize the biodiversity represented by the common functional genes; (3) to investigate the subsurface biogeography as revealed by this subset of genes; and (4) to explore the possibility of using metagenomic data for evolutionary study. The ubiquitous functional genes are NarV, NPD, PAPS reductase, NifH, NifD, NifK, NifE, and NifN genes. Although these eight common functional genes were taxonomically and phylogenetically diverse and distinct from each other, the dissimilarity between samples did not correlate strongly with geographical or environmental parameters or residence time of the water. Por genes homologous to those of Thermodesulfovibrio yellowstonii detected in all metagenomes were deep lineages of Nitrospirae, suggesting that subsurface habitats have preserved ancestral genetic signatures that inform the study of the origin and evolution of prokaryotes.

The analysis of carbon type distribution and chemical structure of natural organic matter (NOM) by 13C NMR spectroscopy is important for understanding its origins and reactivity. While prior work has used solution-state NMR, solid-state NMR has the potential to provide this information with less instrument time and sample processing, while providing an array of advanced filtering techniques. Quantitative and qualitative analyses with 13C solid-state magic angle spinning (MAS) NMR techniques are described for three commercially available samples and one fulvic acid sample isolated from the Rio Grande in New Mexico. This study demonstrates the utility of solid-state 13C NMR for aquatic NOM structural characterization by determining the % carbon type for three standard natural organic materials and comparing these results to the existing solution-state 13C NMR determinations. The solid-state 13C MAS NMR results are used to determine % carbon distribution, estimates of elemental composition (%C, %H, %(O+N)), aromatic fraction (fa), nonprotonated aromatic fraction (faN), an estimate of aromatic cluster size, and ratio of sp2 to sp3 carbons. Additionally, Gaussian deconvolution is used for a more detailed analysis of carbon type than frequency band integration techniques. The solid-state 13C NMR results of these analyses indicate the chemical composition of Rio Grande fulvic acid has higher aromatic fraction and nonprotonated aromatic fraction (fa =0.32, faN = 0.21) and a lower sp2/sp3 fraction and cluster size (sp2/sp3 = 0.66, C = 6) compared to Suwannee River fulvic acid (fa = 0.18, faN = 0.10, sp2/sp3 = 0.82, C = 8).

Ethnotraditional use of plant-derived natural products plays a significant role in the discovery and development of potential medicinal agents. Plants of the genus Taraxacum, commonly known as dandelions, have a history of use in Chinese, Arabian and Native American traditional medicine, to treat a variety of diseases including cancer. To date, however, very few studies have been reported on the anti-carcinogenic activity of Taraxacum officinale (TO). In the present study, three aqueous extracts were prepared from the mature leaves, flowers and roots, and investigated on tumor progression related processes such as proliferation and invasion. Our results show that the crude extract of dandelion leaf (DLE) decreased the growth of MCF-7/AZ breast cancer cells in an ERK-dependent manner, whereas the aqueous extracts of dandelion flower (DFE) and root (DRE) had no effect on the growth of either cell line. Furthermore, DRE was found to block invasion of MCF-7/AZ breast cancer cells while DLE blocked the invasion of LNCaP prostate cancer cells, into collagen type I. Inhibition of invasion was further evidenced by decreased phosphorylation levels of FAK and src as well as reduced activities of matrix metalloproteinases, MMP-2 and MMP-9. This study provides new scientific data on TO and suggests that TO extracts or individual components present in the extracts may be of value as novel anti-cancer agents.

Plants used in folklore medicine continue to be an important source of discovery and development of novel therapeutic agents. In the present study, we determined the effects of crude aqueous extracts of a panel of medicinal plants on the growth and invasion of cancer cells. Our results showed that extracts of L. tridentata (Creosote Bush) and J. communis L. (Juniper Berry) significantly decreased the growth of MCF-7/AZ breast cancer cells. The latter as well as A. californica (Yerba Mansa) inhibited invasion into the collagen type I gel layer. Furthermore, the phosphorylation levels of extracellular signal-regulated kinase 1 and 2 (ERK1/2) decreased when the cells were exposed to aqueous extracts of L. tridentata, J. communis L. and A. californica. This study provides original scientific data on the anticancer activity of selected aqueous medicinal plant extracts used in traditional medicine.

This study investigated the effects of iron on natural organic matter (NOM) absorbance, fluorescence, and molecular weight. Addition of iron(III) to 5 and 10 mg C/L XAD-8 isolated NOM samples at pH 5.5 caused absorbance of visible light to increase, fluorescence intensity of peaks at excitation/emission wavelengths 230/435 nm and 320/450 nm to decrease, and a small shift from intermediate to higher molecular weight components. Iron(II) had little or no effect on XAD-8 isolate properties. Addition of iron(III) to XAD-4 isolated NOM solutions also caused absorbance of visible light to increase. Iron(III) addition to XAD-4 isolate solutions caused a greater decrease in fluorescence intensity than was observed for the XAD-8 isolate, but little or no change in the molecular weight distribution. Overall, our results suggest that the effects of iron on NOM molecular weight, absorbance, and fluorescence properties depend upon the redox state of iron and the composition of the NOM. These results also suggest that the potential effects of iron should be considered when using fluorescence to infer NOM provenance or structure.

Native American medicinal plants are traditionally used to prevent and treat a variety of diseases, including cancer. These herbal preparations are alleged to have many biological activities, such as stimulation or suppression of immune responses and antiproliferative effects on cancer cells. In the present study, we investigated the effects of aqueous and ethanol extracts from two Native American plants, Ligusticum porteri (Osha) and Anemopsis californica (Yerba Manza), on the growth of human MCF-7/AZ breast and HCT8/E11 colon cancer cells. The aqueous and ethanol extracts from A. californica potently inhibited growth of MCF-7/AZ in a concentration-dependent manner, whereas the growth of HCT8/E11 was unaltered. Extracts from L. porteri showed no activity on either cell line. In addition, we observed that the extracellular signal-regulated protein kinase 1 and 2 (ERK1/2) activities were markedly decreased when exposed to both extracts from A. californica. These results suggest that the growth inhibitory effect of A. californica in breast cancer cells is ERK-mediated.

Les cellules phytoplanctoniques vivantes liberent une fraction variable du carbone inorganique fixe lors de la photosynthese sous forme de composes organiques dissous extracellulaires. Les pourcentages rapportes dans la litterature varient de 0 % a 80 %. Malgre cette grande etendue et des effets potentiellement importants sur les flux de carbone et les reseaux trophiques, l'etat actuel des connaissances sur le role des variables environnementales et des especes phytoplanctoniques de ce processus demeure incomplet. En particulier, il n'existe aucune estimation de la liberation de carbone organique dissous par Prochlorococcus, une cyanobacterie marine consideree comme l'organisme oxygenique phototrophe dominant des oceans. Nous rapportons des taux de liberation extracellulaire de composes organiques dissous provenant de deux souches axeniques de Prochlorococcus, representant des ecotypes differents (MED4 et MIT9312), cultivees sous des conditions d'abondance en nutriments et limitees pour le phosphore. Des techniques independantes basees sur le tracage de 14 C-bicarbonate et des analyses chimiques du carbone organique particulaire et dissous suggerent que la liberation de carbone organique dissous dans le milieu environnant varie entre 9 et 24 % du carbone inorganique total assimile. Cette liberation est legerement inferieure pour les cultures limitees par le phosphore. Entre 4 et 20 % de la matiere organique liberee est composee d'acides carboxyliques de faibles poids moleculaires, tous des composes connus comme etant hautement labiles pour les bacteries heterotrophes. Dans les oceans oligotrophes ou Prochlorococcus domine la production primaire, ce processus pourrait contribuer de facon majeure au reservoir de substrats organiques disponibles pour les heterotrophes microbiens.