Removal of Cyanide Contaminants from Rhizosphere Soil

Cyanide and cyanide-containing compounds from anthropogenic sources can be an environmental threat because of their potential toxicity. A remediation option for cyanide-contaminated soil may be through the use of plants and associated rhizosphere microorganimsms that have the ability to degrade cyanide compounds. Cyanogenic plant species are known to produce cyanide, but they also have the ability to degrade these compounds. In addition, the presence of these plants in soil may result in an increase in cyanide degrading microorganisms in the rhizosphere. Two cyanogenic species (Sorghum bicolor and Linum usitassium) and a noncyanogenic species (Panicum virgatum) were selected for a 200-day phytoremediation study to assess their potential use for removal of cyanide from soil. For both cyanogenic species, approximately 85% of the iron cyanide in soil was removed, whereas very little iron cyanide was removed in the unvegetated control or in the presence of Panicum virgatum. In addition, the activity of microbial communities in the rhizosphere of cyanogenic plants was higher than in cyanide-contaminated soil from unvegetated soil.     

A Novel Phosphate-Accumulating Bacterium Identified in a Bioreactor for Phosphate Removal from Wastewater

Microbiology - Abstract—Biotechnologies involving phosphate-accumulating organisms, which collect inorganic phosphates from the medium as polyphosphates during cyclic growth under aerobic and...     

Mercury Removal from Air by a Fiber-Based Bioreactor

A partial removal of metallic mercury from air by fiber-based trickle-bed bioreactors was observed. Up to 50 to 65% of the inlet mercury concentrations of 35 to 70 µg/m³ were removed by immobilized live Pseudomonas bacteria for up to 275 hours at a residence time of 1 min. Ninety to 125% of the adsorbed mercury was recovered by a direct assay after dismantling the bioreactors, thus confirming that the observed mercury removal was due to its adsorption by biomass rather than wet scrubbing followed by evaporation. However, mercury removal at a lower inlet concentration (23 µg/m³) was negligible, with a poor material balance. The adsorbed mercury at higher inlet concentrations was not removed from the biomass by a 2-week washing after conclusion of the mercury adsorption experiment, which indicates a strong mercury binding by bacteria. The volatile organic compound removal efficiency was not affected by the presence of up to 70 µg/m³ of metallic mercury in the air.     

Removal of Petroleum Contaminants Through Bioremediation with Integrated Concepts of Resource Recovery: A Review

There is an upsurge in industrial production to meet the rising demands of the rapidly growing population globally. The enormous energy demand of the growing economies still depends upon petroleum. It has also resulted in environmental pollution due to the release of petroleum origin pollutants. Soil and aquifers, especially in the direct impact zones of petroleum refineries, are the worst hit. The integrated concept of bioremediation and resource recovery offers a sustainable solution to mitigate environmental pollution. It involves biodegradation, a benign utilization of toxic wastes, and the recycling of natural resources. Bioremediation is considered an integral contributor to the emerging concepts of bio-economy and sustainable development goals. This review article aims to provide an updated overview of bioremediation involving petroleum-based contaminants. Microbial degradation is discussed as a promising strategy for petroleum refinery effluent and sludge treatment. The review also provides an insight into resource reuse and recovery as a holistic approach towards sustainable refinery waste treatment. Furthermore, the integrated technologies that deserve in-depth exploration for future study in the refinery sector are highlighted in the present study.Graphical abstract      

A Comparison of Hydrocarbon Vapor Attenuation in the Field with Predictions from Vapor Diffusion Models

This study used field data from three sites in Southern California to evaluate vapor phase transport from: (1) free product (die-sel and gasoline spill) on groundwater; (2) dissolved benzene (gasoline spill) in groundwater; and (3) hydrocarbon-impacted soil (gasoline spill) in the vadose zone. A sampling program to evaluate the vapor pathway included the following: vertical profile data, minimal purging prior to sample collection, field analysis of data, confirmation of field data using a fixed laboratory analysis, and soil physical property data. Comparison of hydrocarbon vapor concentrations measured in this field study with those calculated using vapor diffusion models suggest that an additional attenuation factor of between 500 and 35,000 is needed to account for observed concentrations. Comparison of hydrocarbon profiles with oxygen, carbon dioxide, and methane values is consistent with the interpretation that biodegradation is primarily responsible for the observed attenuation. Therefore, vapor pathway models that do not account for bioattenuation will result in a large overesti-mation of the risk at spill sites and will not be consistent with field data.     

Orthonasal and Retronasal Odorant Identification Based upon Vapor Phase Input from Common Substances

Subjects were trained to identify by assigned number commonsubstances presented as vapor phase stimuli via an orthonasalor a retronasal route. Following training, odorant identificationlearning was evaluated by measuring ability to correctly identifyto a criterion. Those who met the criterion were then testedfirst with the stimuli presented to the nares that differedin location from the nares used in training, and second to thenares that corresponded in location to the nares used in training.It was found that, under conditions of natural retronasal breathing,orthonasally trained subjects made correct identifications on{small tilde}80% of the trials upon retronasal testing, butfor the following orthonasal testing identifications were significantlymore frequent, approaching 100% correct. After subsequent retronasaltraining, the same subjects' orthonasal identifications remainedsignificantly higher, although identifications improved to {smalltilde}92% correct on retronasal trials. Other subjects wereinstructed in a breathing technique designed to enhance retronasalstimulation. After orthonasal training, retronasal testing ofthese subjects still gave significantly fewer correct identificationsthan orthonasal testing, notwithstanding the modified retronasalbreathing, but after subsequent retronasal training correctidentifications by these subjects no longer differed significantlybetween orthonasal and retronasal testing. Efficacy of modifiedretronasal breathing was confirmed in two subsequent experiments.The observed substantial positive transfers between retronasaland orthonasal odorant identification training and testing locidemonstrate that these odorant pathways do not subserve completelyindependent olfactory systems, while the less accurate identificationsvia the retronasal route, unless instruction in retronasal breathingwas given, suggest a difference in the efficiency with whichodorants are normally delivered to the olfactory mucosa. Chem.Senses 21: 529–543, 1996.     

Resistances to the Diffusion of Gas and Vapor in Leaves

Considerable error may be incurred when the component leaf resistances to gases are calculated from the rates of photosynthesis and transpiration measured for the entire leaf. This is due to the fact that there are two parallel pathways for diffusion — through the upper and the lower leaf surfaces — which in most leaves are asymmetrical. True values for the resistances, and predictions of the results of their modification, have been obtained from separate measurements of the photosynthesis and transpiration via the two leaf surfaces.     

Evaluation of the Kinetic Parameters of Trickle Bed Vapor Phase Bioreactors

The dependence of toluene elimination capacity on its load was determined in five small-scale reactors filled with glass beads carrying biocatalyst cells. With an increase in the operation time, the calculated maximum elimination capacity was shown to increase in parallel with the biomass density in the biocatalyst bed. A fivefold increase in the trickling rate did not affect the reactor performance. A simplified mathematical model for evaluating the minimal required biocatalyst bed volume at a certain loading was developed based on the experimental curve of elimination capacity versus loading.     

Removal of Styrene from Waste Gas Using a Biological Trickling Filter

Biodegradation of styrene in a biological trickling filter on lava stones was investigated, firstly, with the addition of silicon oil and, secondly, without the addition of silicon oil. After 400 days of trial runs the experimental results revealed that the biodegradation capacity of styrene in the trickling filter reached 537 g/m³ × h with a degradation yield of 96.8 % at an air inlet concentration of 1.06 g/m³ of styrene and a space velocity of 157 m/h in the presence of silicon oil. A removal of styrene up to 2.9 kg/m³ × h was obtained when the styrene input concentration in a constant inlet air flow of 0.78 m³/h was increased up to 6.6 g/m³. Interestingly, it was observed that after a period of 400 days, the seven dominant strains were completely different from those present in the inoculum. Surprisingly, this population was able to grow in an aqueous liquid phase without silicon oil on a styrene concentration of 45.5 g/L. In the biological trickling filter with lava stones but without silicon oil, the biodegradation capacity of styrene was 464 g/m³ × h with a removal yield of 98.3 % at an air inlet concentration of 1.03 g/m³ of styrene and a space velocity of 137 m/h. As in the presence of silicon oil, a removal of styrene of up to 2.375 kg/m³ × h was achieved when the air flow rate was kept constant and the styrene input concentration was increased. These experiments suggested that the biphasic medium could be very efficiently used for the selection of adapted strains for the removal of insoluble or poorly soluble organic compounds, rather than being used for long‐term degradation under industrial conditions.     

Focus on Metabolism: Glutathionylation and Reduction of Methacrolein in Tomato Plants Account for Its Absorption from the Vapor Phase

A large portion of the volatile organic compounds emitted by plants are oxygenated to yield reactive carbonyl species, which have a big impact on atmospheric chemistry. Deposition to vegetation driven by the absorption of reactive carbonyl species into plants plays a major role in cleansing the atmosphere, but the mechanisms supporting this absorption have been little examined. Here, we performed model experiments using methacrolein (MACR), one of the major reactive carbonyl species formed from isoprene, and tomato (Solanum lycopersicum) plants. Tomato shoots enclosed in a jar with MACR vapor efficiently absorbed MACR. The absorption efficiency was much higher than expected from the gas/liquid partition coefficient of MACR, indicating that MACR was likely metabolized in leaf tissues. Isobutyraldehyde, isobutyl alcohol, and methallyl alcohol (MAA) were detected in the headspace and inside tomato tissues treated with MACR vapor, suggesting that MACR was enzymatically reduced. Glutathione (GSH) conjugates of MACR (MACR-GSH) and MAA (MAA-GSH) were also detected. MACR-GSH was essentially formed through spontaneous conjugation between endogenous GSH and exogenous MACR, and reduction of MACR-GSH to MAA-GSH was likely catalyzed by an NADPH-dependent enzyme in tomato leaves. Glutathionylation was the metabolic pathway most responsible for the absorption of MACR, but when the amount of MACR exceeded the available GSH, MACR that accumulated reduced photosynthetic capacity. In an experiment simulating the natural environment using gas flow, MACR-GSH and MAA-GSH accumulation accounted for 30% to 40% of the MACR supplied. These results suggest that MACR metabolism, especially spontaneous glutathionylation, is an essential factor supporting MACR absorption from the atmosphere by tomato plants.Plants emit vast amounts of volatile organic chemicals (VOCs) into the atmosphere. The annual emission of VOCs other than methane is estimated to be approximately 1,300 Tg of carbon (Goldstein and Galbally, 2007), with approximately 90% originating from biogenic sources, of which one-third (approximately 500 Tg of carbon/year) is isoprene (Guenther et al., 1995). In the atmosphere, VOCs undergo the chemical processes of photolysis and reaction with hydroxyl and nitrate radicals (Atkinson and Arey, 2003). Isoprene, for example, is converted into a series of isomeric hydroxyl-substituted alkyl peroxyl radicals, which are further converted into methyl vinyl ketone (MVK; but-3-en-2-one) and methacrolein (MACR; 2-methylprop-2-enal; Liu et al., 2013). These VOCs and their oxygenated products (oVOCs) are important components for the production of ozone and aerosols, and thus have a big impact on atmospheric chemistry and even on the climate system (Goldstein and Galbally, 2007). VOCs and oVOCs are removed from the atmosphere through oxidation to carbon monoxide or dioxide, dry or wet deposition, or secondary aerosol formation (Goldstein and Galbally, 2007). Among these, deposition to vegetation plays a major role in the removal of VOCs and oVOCs from the atmosphere (Karl et al., 2010).A significant portion of the deposition to vegetation is attributable to the uptake of VOCs and oVOCs by plants, and a field study showed that MVK and MACR were immediately lost once they entered a leaf through stomata (Karl et al., 2010). Under growth conditions where stomatal conductance is high enough, the partitioning of VOCs between air and leaf water phases in equilibrium and the capacity of the plant to metabolize, translocate, and store VOCs determine their uptake rate (Tani et al., 2013). The immediate loss in leaves observed with MVK and MACR is indicative of efficient enzymatic reactions metabolizing them; however, the details of the metabolism of these oVOCs have been little investigated so far.The absorption and metabolism of several VOCs by plants have been reported. Airborne ent-kaurene was absorbed by Arabidopsis (Arabidopsis thaliana), Japanese cypress (Chamaecyparis obtusa), and Japanese cedar (Cryptomeria japonica) plants and converted into GAs (Otsuka et al., 2004). Arabidopsis absorbed (Z)-3-hexenal and converted it into (Z)-3-hexen-1-ol or further into (Z)-3-hexen-1-yl acetate using NADPH and acetyl-CoA, probably inside the plant tissues (Matsui et al., 2012). Nicotiana attenuata plants absorbed dimethyl disulfide formed by rhizobacteria (Meldau et al., 2013). The sulfur atom derived from volatile dimethyl disulfide was assimilated into plant proteins. Karl et al. (2010) assumed that aldehyde dehydrogenase, which is involved in detoxification that limits aldehyde accumulation and oxidative stress (Kirch et al., 2004), is involved in the uptake of oVOCs containing an aldehyde moiety; however, they did not provide direct evidence supporting their assumption.Conjugation of VOCs and oVOCs with sugar or glutathione (GSH) is another way to metabolize them. (Z)-3-Hexen-1-ol in the vapor phase was taken up by tomato (Solanum lycopersicum) plants and converted into its glycoside (Sugimoto et al., 2014). (E)-2-Hexenal reacts with GSH spontaneously and/or via glutathione S-transferase (GST) to form hexanal-GSH, which is subsequently reduced to hexanol-GSH (Davoine et al., 2006), although it is uncertain whether airborne (E)-2-hexenal is converted into its corresponding GSH adduct. Glutathionylation of (E)-2-hexenal is common and has been confirmed in grapevine (Vitis vinifera) and passion fruit (Passiflora edulis; Kobayashi et al., 2011; Fedrizzi et al., 2012). The catabolites formed from the GSH adduct in these crops are precursors for important flavor components.Although it is clear that oVOCs are absorbed by vegetation and that their efficient uptake is probably supported by metabolism in plant tissues, the metabolic fates of oVOCs taken up from the vapor phase into plants have been little studied. Here, we performed a series of model experiments using tomato seedlings and MACR to dissect the fates of oVOCs once they entered into plant tissues. To clearly see absorption of MACR and its fates in plant tissues, a model experiment under enclosed conditions with a high concentration of MACR was first carried out. Subsequently, an airflow system with a realistically low concentration of MACR was used. Tomato plants efficiently absorbed MACR. Reduction of the carbonyl moiety and the double bond conjugated to the carbonyl and conjugation with GSH were the major methods of metabolism of exogenous MACR. The metabolism seemed to be involved in the detoxification of reactive carbonyl species, which, in turn, accounted for the oVOC deposition to vegetation.     

Microwave-Assisted Process (MAPTM) for the Extraction of Contaminants from Soil

Laboratory-scale tests were performed to evaluate the use of Environment Canada's patented Microwave-Assisted Process (MAP_TM) for the extraction of petroleum hydrocarbons from contaminated soil. The purpose of these tests was to determine the potential for using the process for large-scale processing of contaminated soil. Tests were performed using three soil types: a certified sediment and certified soil, both contaminated with polycyclic aromatic hydrocarbons (PAHs), and spiked peat soil contaminated with long-chain petroleum hydrocarbons. The test methods used were based on existing MAP techniques that have been proven for the sample preparation of contaminated soils for analytical purposes. The parameters evaluated concentrated on those that are amenable to a continuous large-scale process running at atmospheric pressures. This meant using solvents that are inexpensive and readily available in large volumes, low solvent to material ratios, and optimized energy inputs. In general, it was found that microwaves could be used to enhance the solvent extraction of the contaminants from the soil and that the properties of the soil greatly affected the extent to which the contaminants were removed.     

A Solution for Removal of Resin from Epoxy Sections

Development of a resin-dissolving solution for use at low alkali concentrations is described. Crown ether dissolved in dimethyl-sulfoxide produces a superbasic alkoxide anion. A five minute treatment resulted in complete resin removal from kidney biopsy specimens embedded in Epon 812. Specimens were well stained by Loeffler's methylene blue. Periodic acid-methenamine silver and Giemsa stains yielded good results. Application of PAS reaction and subsequent hematoxylin counterstaining was practicable for diagnosis.     

以Triton X-114液相分离法去除质粒溶液中的内毒素

目的：采用TritonX-114液相分离法去除质粒溶液中的内毒素,以保证实验动物的安全和结果的准确性。方法：通过碱裂解法提取质粒pVAX1和pVAX1-hLDHC,用聚乙二醇6000沉淀对质粒进一步纯化;用TritonX-114抽提的方法,去除质粒溶液中的内毒素。结果：通过3轮TritonX-114抽提,能够将质粒溶液中内毒素水平降至1．95EU／mL,质粒样品的回收率为79．8％,质量保持不变。结论：TritonX-114液相分离法是一种非常有效的去除质粒溶液中内毒素的方法。     

Enhanced Microbial Removal of H2S Using Chlorobium in an Optical-Fiber Bioreactor

The removal rate of H₂S in a scratched optical fiber bioreactor using Chlorobium thiosulfatophilum was 0.87 µmol H₂S oxidized·l/min·mg protein, which was 6.7 times that in an external illuminating reactor. Available light intensity with scratched fibers in the bioreactor was 41 µmol/m²·s about 5 times as much as that with unscratched ones.     

Climate Change,Risks and Contaminants: A Perspective from Studying the Arctic

The Arctic faces threats from climate change and contaminants. Together, these two threats are likely to present surprises centered around the zero-degree isotherm because the phase change of water has enormous potential to affect contaminant transport and transfer, and biological distribution and stress. Particularly at risk are top aquatic predators, migratory species, and species narrowly adapted to ice. These species are most exposed to contaminants, are most likely to become stressed by climate change, or contain within their life cycles efficient vectors of contaminants and diseases. In the Arctic, mercury presents a special case where risks can be altered at many places in the biogeochemical cycle. Atmospheric mercury depletion events offer one such location; however, the methylation of mercury in aquatic systems appears a far more important and presently neglected component of risk from mercury to Arctic ecosystems. Climate variables alter transport, transfer, and capture of contaminants. Therefore, monitoring for contaminants must be conducted with a systems approach that includes climate-related factors. To ensure that the perception of risk is accurate and that priority risks are addressed first, a closer dialogue between scientists, the public, and public administers is urgently required.     

A Method for the Selective Removal of Deoxyribonucleic Acid from Tissue Sections

The deoxyrihonucleic acid (DNA) of chromatin undergoar depurinization on mild acid hydrolysis with a picric acid-formaldehyde mixture (Bouin's fluid). The apurinic acid thus formed is degraded by condensation with aniline and is lost from tissue sections, but ribonucleic acid (RNA) in nucleoli and cytoplasm is well preserved. Technique: Fi in Carnoy's fluid (ethanol:acetic acid 3:1 or ethanol:chloroform:acetic acid 6:3:1) or in aldehydes (10% formalin or 2.5% glutaraldehyde bsered to pH 7.0). Hydrolyse deparaEnii sections 12-24 hr at 27-50 C in Bouin's fluid, wash in distilled water, immerse in 25% (v/v) acetic acid, treat 1 hr at 27-30 C with 10% (v/v) dine in 25% acetic acid, wash in 25% acetic acid and then in water. Stain 10-40 min with 0₃% toluidine blue in 0.05 M potassium biphthalate bder (pH 4.0); rinse in distilled water, pass to 10% (w/v) ammonium molybdate for 1 min, rinse again in water and pass through tert-butanol and xylene to a synthetic resin. Chromatin and chromosomes are pale green; RNA in nucleoli and cytoplasm deep purple.