Pseudomonas fluorescens HK44 represents the first genetically engineered microorganism approved for field testing in the United States for bioremediation purposes. Strain HK44 harbors an introduced ...lux gene fused within a naphthalene degradative pathway, thereby allowing this recombinant microbe to bioluminesce as it degrades specific polyaromatic hydrocarbons such as naphthalene. The bioremediation process can therefore be monitored by the detection of light. P. fluorescens HK44 was inoculated into the vadose zone of intermediate-scale, semicontained soil lysimeters contaminated with naphthalene, anthracene, and phenanthrene, and the population dynamics were followed over an approximate 2-year period in order to assess the long-term efficacy of using strain HK44 for monitoring and controlling bioremediation processes. Results showed that P. fluorescens HK44 was capable of surviving initial inoculation into both hydrocarbon contaminated and uncontaminated soils and was recoverable from these soils 660 days post inoculation. It was also demonstrated that strain HK44 was capable of generating bioluminescence in response to soil hydrocarbon bioavailability. Bioluminescence approaching 166 000 counts/s was detected in fiber optic-based biosensor devices responding to volatile polyaromatic hydrocarbons, while a portable photomultiplier module detected bioluminescence at an average of 4300 counts/s directly from soil-borne HK44 cells within localized treatment areas. The utilization of lux-based bioreporter microorganisms therefore promises to be a viable option for in situ determination of environmental contaminant bioavailability and biodegradation process monitoring and control.
Carbonatites were discovered at Veseloe, North Transbaikalia, Russia in 2002. They are fluorapatite and calcite-bearing dolomite carbonatites and chemically classified as magnesiocarbonatites with ...high P, Ti, Cr and Ni. The Cr content in some parts of the Veseloe carbonatites is 3-4 times higher than average magnesiocarbonatite and results from the presence of partially resorbed polymineralic 3-5 mm diameter aggregates of Cr-rich minerals (magnetite, rutile, titanite, ilmenite, phengite, chlorite, chromite, titanite and talc). These aggregates may well be relict mantle xenoliths. They contain a rutile-magnetite intergrowth observed for the first time in nature and have compositions consistent with minerals from eclogite, kimberlite and mantle xenoliths. In the Veseloe carbonatites dolomite crystallized first, and then calcite, which is the inverse of the order of crystallization seen in most carbonatite complexes. Strontium isotope ratios are consistent with a Riphean mantle source. Carbon and O isotope ratios rule out some processes of alteration (metamorphic dehydration and high temperature hydrothermal alteration by meteoric waters) but do not plot in the accepted box for primary igneous carbonatite. Mineral geothermometers, inclusion measurements and the relict mantle xenoliths suggest petrogenesis by independent production of magnesiocarbonatite melt in the mantle rather than crustal differentiation of a carbonated-silicate parental melt. PUBLICATION ABSTRACT
The paper gives a mineralogical and geochemical characterization of the North Gurvunur deposit, which was discovered in the Eravna ore district. The ore is composed of apatite–magnetite paragenesis. ...Apatite is distinguished by elevated LREE concentrations; some of them are contained in emulsion-type impregnation of monazite. Hematitization, carbonate, quartz, and pyrite veinlets formed at the postore stage, and gypsum–anhydrite mineralization is widespread in the supraore sequence. Two groups of endogenic minerals are distinguished by oxygen isotopic composition. One of them comprises magnetite and apatite, which are characterized by a homogeneous composition throughout the section of the ore lode and are close to the mantle source. The oxygen–isotope temperature calculated for the apatite–magnetite couple (620–800°C) provides evidence for magmatic origin of ore. The δ
18
O of fluid in equilibrium with hematite is 8.0–8.5‰ and shows a certain enrichment in crustal component; carbonates of postore veinlets reveal participation of meteoric water. The study has made it possible to refer the North Gurvunur deposit to the Kiruna type.
Isotope-geochemical study of the Ermakovskoe fluorine–beryllium deposit was carried out to estimate the ore sources and role of host carbonate rocks in its formation. We analyzed oxygen and carbon ...isotope compositions in marbles, skarn carbonates, ore and post-ore parageneses; oxygen isotope compositions in oxides, silicates, apatite; and sulfur isotope composition in sulfides and sulfates. Sources of fluids participating in the rock and ore formation were determined using hydrogen and oxygen isotope compositions in hydroxyl-bearing minerals: phlogopite from marbles, vesuvian from skarns, eudidymite and bertrandite from ore parageneses, and bavenite of the post-ore stage. Isotopic studies suggest crustal source of sulfur, oxygen, and carbon dioxide, while oxygen and hydrogen isotope compositions in the hydroxyl-bearing minerals points to the contribution of meteoric waters in the formation of the fluorine-beryllium ores.
To incorporate into the lambda phage genome, a luxI-based acyl-homoserine lactone (AHL) synthase genetic construct and exploit the autoamplified power of quorum sensing to translate a phage infection ...event into a chemical signature detectable by a lux-based bioluminescent bioreporter, with focus towards facile detection of microbial pathogens. The luxI gene from Vibrio fischeri was inserted into the lambda phage genome to construct a model phage-based biosensor system for the general detection of Escherichia coli. The AHL signalling molecules synthesized upon phage infection are detected by an AHL-specific bioluminescent bioreporter based on the luxCDABE gene cassette of V. fischeri. The assay generates target-specific visible light signals with no requisite addition of extraneous substrate. This binary reporter system was able to autonomously respond to lambda phage infection events at target E. coli concentrations ranging from 1 multiplication 10⁸ to 1 CFU mlsuperscript -1 within 1·5-10·3 h, respectively, in pure culture. When assayed against artificially contaminated lettuce leaf washings, detection within an E. coli inoculum range from 1 multiplication 10⁸ to 130 CFU mlsuperscript -1 was achieved within 2·6-22·4 h, respectively. The initial feasibility of binary phage-based reporter assays indicates that quorum sensing can be used to translate a phage infection event into an autoamplified chemical signature. With further modification, binary phage-based reporter assays may be capable of rapidly and cost effectively detecting pathogenic agents at very low population densities.
We present the results of a study on gabbroic rocks, syenites, pegmatites, carbonatites, and hydrothermal products of the Oshurkovo apatite-bearing massif. The results include Nd and Sr isotope ...ratios; the isotope compositions of carbon and oxygen in calcite; oxygen in apatite, magnetite, and silicate minerals (phlogopite, titanite, diopside, amphibole, K-feldspar, and quartz); sulfur in barite; and hydrogen in mica. The isotopic data are close to the EM-1 enriched mantle values and confirm a comagmatic relationship between the gabbros and carbonatites. The binary plot ɛ
Nd
vs.
87
Sr/
86
Sr demonstrates strong differentiation between silicate rocks and carbonatites, as is the case with the other Late Mesozoic carbonatite occurrences of southwestern Transbaikalia. The oxygen isotope composition of all comagmatic phases also falls within the range of mantle values. A clear trend toward heavier oxygen and lighter carbon isotope compositions is observed in all successively emplaced phases, which is consistent with a trend defined by hydrothermal products formed under the influence of the parent magma chamber. Carbonates formed during the greenstone alteration of gabbroic rocks are enriched in the light oxygen isotope (δ
18
O from −2.8 to −7.3‰), suggesting a contribution of vadose water.
The paper reports Ar-Ar, Rb-Sr, and U-Pb (SHRIMP II) geochronologic data on carbonatites in Transbaikalia, related metasomatically altered rocks, and comagmatic silicate alkaline rocks. Metamorphic ...processes at two carbonatite occurrences were dated at 550–559 Ma (U-Pb and Rb-Sr methods). Geochronologic data make it possible to distinguish two major epochs when carbonatite were formed: Late Mesozoic in southwestern Transbaikalia and Late Riphean-Vendian in northern Transbaikalia. Small carbonatite occurrences are also known in the Vitim and Baikal alkaline provinces, which were formed in the Middle-Late Paleozoic. The Late Mesozoic carbonatite-forming epoch is definitely correlated with the development of the Western Transbaikalia rift structure and the Late Riphean-Vendian epoch, with the breakup of Laurasia in the Late Riphean.
Initially described in 1990, Pseudomonas fluorescens HK44 served as the first whole-cell bioreporter genetically endowed with a bioluminescent (luxCDABE) phenotype directly linked to a catabolic ...(naphthalene degradative) pathway. HK44 was the first genetically engineered microorganism to be released in the field to monitor bioremediation potential. Subsequent to that release, strain HK44 had been introduced into other solids (soils, sands), liquid (water, wastewater), and volatile environments. In these matrices, it has functioned as one of the best characterized chemically-responsive environmental bioreporters and as a model organism for understanding bacterial colonization and transport, cell immobilization strategies, and the kinetics of cellular bioluminescent emission. This review summarizes the characteristics of P. fluorescens HK44 and the extensive range of its applications with special focus on the monitoring of bioremediation processes and biosensing of environmental pollution.
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