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This study quantifies the potential effects of a set of technologies to address water and fertility constraints in rain-fed smallholder agriculture in South Africa, namely in situ water harvesting (WH), external WH, and ecological sanitation (Ecosan, fertilization with human urine). We used the Soil and Water Assessment Tool to model spatiotemporally differentiated effects on maize yield, river flow, evaporation, and transpiration. Ecosan met some of the plant nitrogen demands, which significantly increased maize yields by 12% and transpiration by 2% on average across South Africa. In situ and external WH did not significandy affect the yield, transpiration or river flow on the South Africa scale. However, external WH more than doubled the yields for specific seasons and locations. WH particularly increased the lowest yields. Significant water and nutrient demands remained even with WH and Ecosan management Additional fertility enhancements raised the yield levels but also the yield variability, whereas soil moisture enhancements improved the yield stability. Hence, coupled policies addressing both constraints will likely be most effective for improving food security. [ABSTRACT FROM AUTHOR]

Andersson, Jafet C.M., Alexander J.B. Zehnder, Bernhard Wehrli, and Hong Yang, 2012. Improved SWAT Model Performance with Time-Dynamic Voronoi Tessellation of Climatic Input Data in Southern Africa. Journal of the American Water Resources Association (JAWRA) 48(3): 480-493. DOI: 10.1111/j.1752-1688.2011.00627.x Abstract: In this study, we compared two approaches to obtain climatic time series for the Soil and Water Assessment Tool (SWAT), namely the conventional centroid method and time-dynamic Voronoi tessellation, and assessed the performance of SWAT in simulating discharge and smallholder maize yields in Southern Africa. Climatic time series were estimated with each method. The Voronoi method utilized all available precipitation and temperature data, but the centroid method used only 14.5 and 82.5%, respectively. After centroid processing, sub-basin time series were on average 42 and 63% incomplete, respectively. After Voronoi processing, all time series were complete. SWAT was fed with each climate dataset. Each model setup was independently calibrated and validated against discharge and maize yield. Similar model performance was obtained with both methods for yield. The root mean squared error during calibration was 0.26 and 0.27 t ha−1 for the centroid and Voronoi methods, respectively ( p-value: 0.80). However, daily discharge simulations improved significantly with the Voronoi method. The coefficient of determination increased from 0.24 to 0.39 in the calibration period ( p-value: 9.6 × 10−13) and from 0.41 to 0.48 in the validation period ( p-value: 3.1 × 10−3). The Voronoi method improved the simulation of the river flow regime. The largest improvements were obtained in data scarce situations, at high spatial and temporal resolution, and where the centroid method performed the worst. [ABSTRACT FROM AUTHOR]

Abstract: In this study we explore the potential impacts of two strategies, namely in situ water harvesting (in situ WH) and fertilisation with stored human urine (Ecosan), to increase the water and nutrient availability in rain-fed smallholder agriculture in South Africa''s Thukela River basin (29,000km2). We use the soil and water assessment tool (SWAT) to simulate potential impacts on smallholder maize yields, river flow regimes, plant transpiration, and soil and canopy evaporation during 1997–2006. Based on the results, the impacts on maize yields are likely to be small with in situ WH (median change: 0%) but significant with Ecosan (median increase: 30%). The primary causes for these effects are high nitrogen stress on crop growth, and low or untimed soil moisture enhancement with in situ WH. However, the impacts vary significantly in time and space, occasionally resulting in yield increases of up to 40% with in situ WH. Soil fertility improvements primarily increase yield magnitudes, whereas soil moisture enhancements reduce spatial yield variability. Ecosan significantly improves the productivity of the evaporative fluxes by increasing transpiration (median: 2.8%, 4.7mm season−1) and reducing soil and canopy evaporation (median: −1.7%, −4.5mm season−1). In situ WH does not generally affect the river flow regimes. Occasionally, significant regime changes occur due to enhanced lateral and shallow aquifer return flows. This leads to higher risks of flooding in some areas, but also to enhanced low flows, which help sustain aquatic ecosystems in the basin. [Copyright &y& Elsevier]

Increasing water scarcity in China demands a more detailed analysis of water use in different sectors. In this paper, China's food import and export levels are analyzed in light of water availability. Their contributions to national water management in the form of virtual water are also evaluated. The findings show that the virtual water trade has developed unconsciously. This trend has been greatly influenced by micro- and macro-economic conditions, as well as fluctuations in weather conditions. Given the intensification of water scarcity, future food policy should promote an active application of virtual water strategies (such as virtual water trade and agricultural structure adjustment) to improve food security and sustainable water uses. With the progressive liberalization of food markets in China, virtual water trade is likely to play a more important role in future water resources management. [ABSTRACT FROM AUTHOR]

After nearly half a century of planning, the construction of the controversial south-to-north water transfer (SNWT) project in China was officially launched just before the end of 2002. This paper looks into the decision-making process of the project in the context of the country's transition from a centrally-planned economy to a market economy, rapid economic development, and severe environmental degradation. Uncertainties concerning future water demand in individual sectors are examined with reference to the latest projection prior to the launch of the project. Adjustment of project objectives and shut of the focal issues concerned over the years are elaborated. The analysis suggests a high degree of uncertainty in future water demand. The expansion of project objectives to include ecosystem recovery in the late 1990s, however provided a decisive argument for implementing the project as no other alternative was considered available to meet the estimated ecosystem water requirement Consequently, remaining doubts on the need for the project and concerns on adverse environmental impacts have tended to be sidelined. With the implementation of the project, the government is caught in a dilemma of keeping water prices low to substantiate the economic needs and improving water use efficiency to honor the environmental objective of the project. [ABSTRACT FROM AUTHOR]

Addresses the water-food challenges facing water-scarce countries. Implications for the world food economy; Use of several southern Mediterranean countries as a case study; Changes in cereal production and sources of supply; Per capita daily food consumption and dietary structure in 1999; Overview of net food imports and virtual water equivalent.

Investigates the effects of global regulatory hns gene on Escherichia coli solid surfaces. Mechanism of biofilm formation; Importance of solid surface adhesion in biofilm formation; Regulation of flagellar genes expression and lipopolysaccharide production.

Catechols can undergo a variety of chemical reac- tions. In this review, we particularly focus on complex formations and the redox chemistry of catechols, which play an inportant role in the toxicity of catechols. In the presence of heavy metals, such as iron or copper, stable complexes can be formed. In the presence of oxidizing agents, catechols can be oxidized to semiquinone radicals and in a next step to o-benzoquinones. Heavy metals may catalyse redox reactions in which catechols are involved. Further chemical properties like the acidity constant and the lipophilicity of different catechols are shortly described as well. As a consequence of the chemical properties and the chemical reactions of catechols, many different reactions can occur with biomolecules such as DNA, proteins and membranes, ultimately leading to non-repairable damage. Reactions with nucleic acids such as adduct formation and strand breaks are discussed among others. Interactions with proteins causing protein and enzyme inactivation are described. The membrane-catechol interactions dis- cussed here are lipid peroxidation and uncoupling. The deleterious effect of the interactions between catechols and the different biomolecules is dis- cussed in the context of the observed toxicities, caused by catechols. [ABSTRACT FROM AUTHOR]

Discusses the implications of water scarcity in the North China Plain for grain supply and trade. Overview of water-resource endowments in the region; Changes in irrigated areas and sources of irrigation water in the North China Plain; Projections on water increment in the North China Plain provinces.

Studies the in vitro adenosine triphosphate (ATP) regeneration from polyphosphate and adenylic acid (AMP) by polyphosphate. Expression of PPT; Regeneration of ATP by PPT/AdK; AS precipitation; Involvement of AdK or PPK in ATP formation; Substrate specificity.

Looks at a study which evaluated the low-frequency horizontal gene transfer process of the chlorocatechol degradative genes, from Pseudomonas sp. strain B13. Details on the usage of activated-sludge microcosms; Development of a metabolic pathway for chlorobenzene degradation; Methodology used to conduct the study; Results of the study.

Examines the interaction of polymers in bacterial adhesion, with emphasis on the role of electrostatic and acid-base (hydrophobic) interactions. Reference to the interaction of bacterial surface polymers; Importance of bacterial adhesion to solids; Indication that adhesion to solids controls the mobility of bacteria in the subsurface.

Provides information on a study showing the tfdK gene uptake of 2,4-dichlorophenoxyacete by Ralstonia eutropha JMP134(pJP4) to be an energy-dependent process. Information on the uptake of 2,4-D by the tfdK mutant; Detailed information on the modelling of TfdK transport activity; Conclusion reached on the study.

Focuses on the impact of business on the environment and vice versa. Views of environmentalists on the way business can hamper the environment; Impact of environment protection legislations on businesses Effect of a shift from the notion of environment protection to resource management.

Abstract: This study investigates food trade patterns in relation to water resources availability in the Southern and Eastern Mediterranean countries (SEMED). Examinations show that most of these countries have a high dependence on the import of water intensive crops – cereal, vegetable oil and sugar, in the domestic food supply. The region as a whole is marginally a net exporter of fruits and vegetables, while variations are substantial across countries. Multi-variable regression analyses show that intensification of water scarcity is an important factor in explaining the increase in food import in the SEMED countries during the past two decades. It also finds that while GDP per capita has a strong influence on the level of food import in a country, its impact on changes in the import during the same period is rather modest. No significant relationship is found between the trade of fruits and vegetables and water resources availability. The projection on food import with respect to the decline in per capita water resources availability results in an increase of 40%, 39% and 14%, respectively, for cereal, vegetable oil and sugar by 2020 in the region, holding other factors constant. The European Union (EU) is the major food trade partner of the SEMED countries, except for cereal. About 70% of the fruit export and 55% of the vegetable export of the region currently go to the EU market. Expanding the export of fruits and vegetables is conducive to improving the value of water use in the SEMED countries. However, the expansion is constrained partly by the barriers in the destination markets, notably the EU. [Copyright &y& Elsevier]

Irrigation plays an important role in increasing food production in China. The impact of irrigation on crop yield ( Y), crop water productivity (CWP), and production has not been quantified systematically across regions covering the whole country. In this study, a GIS-based EPIC model (GEPIC) was applied to simulate Y and CWP for winter wheat ( Triticum aestivum L.) in China at a grid resolution of 5 arc-minutes and to analyze the impacts of reducing irrigation water on wheat production. The findings show that irrigation is especially important in improving CWP of winter wheat in the North China Plain (NCP), the “bread basket” of China. On average, the provincial aggregate CWP was 56% higher under the irrigated than that under the rainfed conditions. The intensification of water stress and the associated increase in environmental problems in much of the NCP require critical thoughts about reducing water allocation for irrigated winter wheat. Two scenarios for irrigation reduction in the NCP provinces are presented: reducing irrigation depth (S1), and replacing irrigated winter wheat by rainfed winter wheat (S2). The simulation results show that S1 and S2 have similar effects on wheat production when the reduction in irrigation water supply is below 20% of the current level. Above this percentage, S2 appears to be a better scenario since it leads to less reduction in wheat production with the same amount of water saving. [ABSTRACT FROM AUTHOR]

Abstract: With population growth and economic development, the agricultural sector is facing the challenge to produce more food with less water. Crop water productivity (CWP) is important for understanding water–food relationships. It also provides a basis for the assessment of water use efficiency embodied in global food trade. However, traditional methods are not sufficient for estimating CWP on a global scale considering large spatial and temporal variations across different geographical locations. In this paper, a GIS-based EPIC model (GEPIC) is developed and tested to estimate wheat (Triticum aestivum L.) yield and CWP at a grid resolution of 30′ on the land surface. A comparison between simulated yields and FAO statistical yields in 102 countries over 10 years shows a good agreement. The simulated CWP is also mostly in line with the CWP reported in the literature. The simulation results show that compared with rainfed wheat, irrigated wheat has higher frequencies for high CWP (>0.8kgm−3) and lower frequencies for low CWP (<0.8kgm−3). This is likely because irrigation can provide timely water supply to crop development and the management of irrigated crops is usually more intensive than in rainfed production. A strong linear relation is found between CWP and yield. High wheat yield and CWP appear in the European countries, especially those in western and northern Europe. Low wheat yield and CWP are seen in most African countries. The simulation using GEPIC, however, shows that wheat yield and CWP in many African countries could increase substantially with sufficient water supply and fertilizer application. Variations in CWP across countries suggest that global water use could be reduced through food trade. Calculations indicate a saving of 77×109 m3 of water in 2000 through international wheat trade as a result of relatively high CWP in major exporting countries. However, the simulation results also suggest that an overall improvement in CWP through better crop management practices in local areas could make a greater contribution to the reduction in global water use. [Copyright &y& Elsevier]

Production of curli, extracellular structures important for biofilm formation, is positively regulated by OmpR, which constitutes with the EnvZ protein an osmolarity-sensing two-component regulatory system. The expression of curli is cryptic in most Escherichia coli laboratory strains such as MG1655, due to the lack of csgD expression. The csgD gene encodes a transcription activator of the curli-subunit-encoding csgBA operon. The ompR234 up-mutation can restore csgD expression, resulting in curli production and increased biofilm formation. In this report, it is shown that ompR234-dependent csgD expression, in addition to csgBA activation during stationary phase of growth, stimulates expression of the yaiC gene and negatively regulates at least two other genes, pepD and yagS. The promoter regions of these four genes share a conserved 11 bp sequence (CGGGKGAKNKA), necessary for csgBA and yaiC regulation by CsgD. While at both the csgBA and yaiC promoters the sequence is located upstream of the promoter elements, in both yagS and pepD it overlaps either the putative -10 sequence or the transcription start point, suggesting that CsgD can function as both an activator and a repressor. Adhesion experiments show that csgD-independent expression of both yagS and pepD from a multicopy plasmid negatively affects biofilm formation, which, in contrast, is stimulated by yaiC expression. Thus it is proposed that CsgD stimulates biofilm formation in E. coli by contemporary activation of adhesion positive determinants (the curli-encoding csg operons and the product of the yaiC gene) and repression of negative effectors such as yagS and pepD. [ABSTRACT FROM AUTHOR]

With water scarcity becoming an increasing constraint to food production in northern China, pricing mechanism has been given a high priority in dealing with the problem. Using selected irrigation districts in northern China as a case study, this paper probes the effectiveness of pricing-based water policies in addressing challenges facing irrigated agriculture under China’s current water management institutions. The examination shows that the rapid increase in irrigation cost during the past decade has failed to generate a force for water conservation. Over-exploitation of groundwater resources has even intensified with the shift to higher value-added but often more water intensive crops. Based on a normative analysis of water demand curves, the logic behind the reluctance for water authorities and farmers to conserve water is elaborated. The result suggests that pricing irrigation alone is not a valid means of encouraging water conservation under the current irrigation management institutions. Clearly defined and legally enforceable water rights and responsibilities for water operators and users in the irrigation system are the foundation underlying the incentives for conserving water and improving the irrigation efficiency. [Copyright &y& Elsevier]

Transcription of the Escherichia coli aidB gene is controlled by an EσS-dependent promoter (PaidB) and is poorly transcribed by the Eσ70 form of RNA polymerase in the absence of additional factors. In this report, we investigate the interaction between PaidB and either the Eσ70 or the EσS forms of RNA polymerase in vitro. We show that although Eσ70 can bind the aidB promoter, its interaction with the promoter results in the formation of an open complex inefficient in transcription initiation and sensitive to heparin challenge. Deletion of the C residue at position −13 of PaidB (Δ-13C) slightly impaired transcription initiation by EσS, consistent with the role of −13C as a specific feature of EσS-dependent promoters. However, EσS could still bind and initiate transcription from the Δ-13C mutant aidB promoter more efficiently than Eσ70, suggesting that sequence elements other than the −13C play an important role in specific promoter recognition by EσS. [Copyright &y& Elsevier]

Focuses on the role of pension funds in sustaining corporate involvements. Influence of pension funds in global investment decisions; Details on the pillars of the US pension system; Characteristics of tools for pension fund management. INSETS: The Three Pillars of the U.S. Pension System;Sustainability or Socially Responsible Stock Indexes.

Diffusion of octane from oily droplets in different microscale settings was measured using Escherichia coli expressing the stable green fluorescent protein (GFP) from the alkB promoter of Pseudomonas oleovorans. GFP fluorescence intensities were determined quantitatively at the single-cell level after 1.0 or 2.5 h incubation and compared with different calibration series using known concentrations of octane. By immobilizing the E. coli sensor cells on the bottom glass plate of a microscope flow chamber, it was possible to monitor the diffusion process for octane in aqueous solution as a function of time and distance from non-aqueous phase droplets of octane alone or oily octane mixtures. When a gas phase was included in the flow chambers, octane transport could be demonstrated from the oily mixtures to the cells through both gas and liquid phase. Assays of non-immobilized sensor cells in microdroplets in the presence or absence of soil particles incubated with octane through the vapour phase revealed a slight reduction in the total amount of induced E. coli cells in the presence of soil. Our results indicate the power of using GFP-marked single-cell biosensors in determining microscale bioavailability of organic pollutants. [ABSTRACT FROM AUTHOR]

Carbon monoxide dehydrogenase was purified to apparent homogeneity from Methanothrix soehngenii. In contrast with the carbon monoxide dehydrogenases from most other anaerobic bacteria, the purified enzyme of Methanothrix soehngenii was remarkably stable towards oxygen and it was only slightly inhibited by cyanide. The native molecular mass of the carbon monoxide dehydrogenase of Methanothrix soehngenii determined by gel filtration was 190 kDa. The enzyme is composed of subunits with molecular mass of 79.4 kDa and 19.4 kDa in an α2β2 oligomeric structure. The enzyme contains 1.9 ± 0.2 (n = 3) mol Ni/mol and 19 ± 3 (n = 3) mol Fe/ mol and it constitutes 4% of the soluble cell protein. Analysis of enzyme kinetic properties revealed a Km of 0.7 mM for CO and of 65 gM for methyl viologen. At the optimum pH of 9.0 the Vmax was 140 µmol of CO oxidized min-1 mg protein-1. The enzyme showed a high degree of thermostability. [ABSTRACT FROM AUTHOR]

Presents a study which shows the complete degradation of both enantiomers of the chiral herbicide dichlorprop [9RS)-2-(2,4-dichlorophenoxy)propanoic acid by Sphingomonas herbicidovorans (MH). What was revealed by the experiments on the substrate specificity of the putative transport system; Suggestion of the existence of specific systems; Description of the two distinct uptake systems of chiral phenoxypropionic acid.

Failure to setup a large-scale hydrological model correctly may not allow proper calibration and uncertainty analyses, leading to inaccurate model prediction. To build a model with accurate accounting of hydrological processes, a data discrimination procedure was applied in this study. The framework uses a hydrological model of Alberta built with the Soil and Water Assessment Tool (SWAT) program. The model was used to quantify the causes and extents of biases in predictions due to different types of input data. Data types represented different sources of errors, including input data (e.g., climate), conceptual model (e.g., potholes, glaciers), and control structure (e.g., reservoirs, dams). The results showed that accounting for these measures leads to a better physical accounting of hydrological processes, significantly improving the overall model performance. The procedure used in this study helps to avoid unnecessary and arbitrary adjustment of parameters to compensate for the errors in the model structure. [ABSTRACT FROM AUTHOR]

Summary: This study analyzes the impact of climate change on freshwater availability in Africa at the subbasin level for the period of 2020–2040. Future climate projections from five global circulation models (GCMs) under the four IPCC emission scenarios were fed into an existing SWAT hydrological model to project the impact on different components of water resources across the African continent. The GCMs have been downscaled based on observed data of Climate Research Unit to represent local climate conditions at 0.5° grid spatial resolution. The results show that for Africa as a whole, the mean total quantity of water resources is likely to increase. For individual subbasins and countries, variations are substantial. Although uncertainties are high in the simulated results, we found that in many regions/countries, most of the climate scenarios projected the same direction of changes in water resources, suggesting a relatively high confidence in the projections. The assessment of the number of dry days and the frequency of their occurrences suggests an increase in the drought events and their duration in the future. Overall, the dry regions have higher uncertainties than the wet regions in the projected impacts on water resources. This poses additional challenge to the agriculture in dry regions where water shortage is already severe while irrigation is expected to become more important to stabilize and increase food production. [ABSTRACT FROM AUTHOR]

Food security and water scarcity have become two major concerns for future human's sustainable development, particularly in the context of climate change. Here we present a comprehensive assessment of climate change impacts on the production and water use of major cereal crops on a global scale with a spatial resolution of 30 arc-minutes for the 2030s (short term) and the 2090s (long term), respectively. Our findings show that impact uncertainties are higher on larger spatial scales (e.g., global and continental) but lower on smaller spatial scales (e.g., national and grid cell). Such patterns allow decision makers and investors to take adaptive measures without being puzzled by a highly uncertain future at the global level. Short-term gains in crop production from climate change are projected for many regions, particularly in African countries, but the gains will mostly vanish and turn to losses in the long run. Irrigation dependence in crop production is projected to increase in general. However, several water poor regions will rely less heavily on irrigation, conducive to alleviating regional water scarcity. The heterogeneity of spatial patterns and the non-linearity of temporal changes of the impacts call for site-specific adaptive measures with perspectives of reducing short- and long-term risks of future food and water security. [ABSTRACT FROM AUTHOR]

Crop production is the single largest cause of human alteration of the global nitrogen cycle. We present a comprehensive assessment of. global nitrogen flows in cropland for the year 2000 with a spatial resolution of 5 arc-minutes. We calculated a total nitrogen input (IN) of 136.60 trillion grams (Tg) of N per year, of which almost half is contributed by mineral nitrogen fertilizers, and a total nitrogen output (OUT) of 148.14 Tg of N per year. of which 55% is uptake by harvested crops and crop residues. We present high-resolution maps quantifying the spatial distribution of nitrogen IN and OUT flows, soil nitrogen balance, and surface nitrogen balance. The high-resolution data are aggregated at the national level on a per capita basis to assess nitrogen stress levels. The results show that almost 80% of African countries are confronted with nitrogen scarcity or nitrogen stress problems, which, along with poverty, cause food insecurity and malnutrition. The assessment also shows a global average nitrogen recovery rate of 59%, indicating that nearly two-fifths of nitrogen inputs are lost in ecosystems. More effective management of nitrogen is essential to reduce the deleterious environmental consequences. [ABSTRACT FROM AUTHOR]

Methanogenesis from main methane precursors H2/CO2 and acetate was investigated in a temperature range of 2–70 °C using sediments from Lake Baldegg, Switzerland. Psychrophilic, psychrotrophic, mesophilic, and thermophilic methanogenic microbial communities were enriched by incubations for 1–3 months of nonamended sediment slurries at 5, 15, 30, and 50 °C. Isotope experiments with slurries amended with 14C-labeled bicarbonate and 14C-2-acetate showed that in the psychrophilic community (enriched at 5 °C), about 95% of methane originated from acetate, in contrast to the thermophilic community (50 °C) where up to 98% of methane was formed from bicarbonate. In the mesophilic community (30 °C), acetate was the precursor of about 80% of the methane produced. When the hydrogen–carbon dioxide mixture (H2/CO2) was used as a substrate, it was directly converted to methane under thermophilic conditions (70 and 50 °C). Under mesophilic conditions (30 °C), both pathways, hydrogenotrophic and acetoclastic, were observed. At low temperatures (5 and 15 °C), H2/CO2 was converted into methane by a two-step process; first acetate was formed, followed by methane production from acetate. When slurries were incubated at high partial pressures of H2/CO2, the high concentrations of acetate produced of more than 20 mM inhibited acetoclastic methanogenesis at a temperature below 15 °C. However, slow adaptation of the psychrophilic microbial community to high acetate concentrations was observed. [ABSTRACT FROM AUTHOR]

To study the effect of strong iron-ligands on steel corrosion, mild steel electrodes were immersed in solutions containing 20 mM phosphate buffer (pH=7.2) and between 0.01 mM and 1 M of either the iron(II)-chelators 2,2′-bipyridine or FerroZine, or the iron(III)-chelators citrate or acetylacetonate. Resulting surface reactions were investigated by quantifying the electrochemical potential (E), the electrochemical polarization resistance (Rp), the corrosion current (Icorr) and the release of iron into solution. The surface was further analyzed by scanning electron microscopy (SEM/SEM-EDAX) and atomic force microscopy. Concentrations of 0.1 mM of any of the chelators led to slight, temporary changes in E, Icorr and Rp. Concentrations of 10 mM resulted in characteristic changes of E, which were the same for all chelators and in the precipitation of FePO4 in the case of citrate and acetylacetonate, or vivianite [Fe3(PO4)2 · 8H2O] in the case of bipyridine and FerroZine. Concentrations of 1 mM of both iron(III)-chelators led to a temporary drop of E similar to that found with 0.1 mM chelator. With iron(II)-chelators, E dropped to about −500 mV before oscillating for several days. The amplitudes of the oscillations were up to 200 mV with periods of 30 and 20–25 min for bipyridine and FerroZine, respectively. [Copyright &y& Elsevier]

Cereal import has played a crucial role in compensating local water deficit. A quantitative account of water deficit and cereal import relations therefore is of significance for predicting future food import demand and formulating corresponding national and international policies. On the basis of data for countries in Asia and Africa, we estimated a water resources threshold with respect to cereal import. Below the threshold, the demand for cereal import increases exponentially with decreasing water resources. There appeared to be a declining trend in the threshold, from 2000 m³/(capita year) in the early 1980s to 1500 m³/(capita year) by the end of the 1990s. Until recently, most countries below the threshold were oil-rich and thus were able to afford cereal import. However, the next 30 yr may see many poor and populous countries dropping below the threshold in association with their rapid population growth and the depletion of fossil groundwater. Water deficit-induced food insecurity and starvation could intensify because cereal import may not be affordable for these countries. [ABSTRACT FROM AUTHOR]

Partial nitrification of ammonium to nitrite under oxic conditions (nitritation) is a critical process for the effective use of alternative nitrogen removal technologies from wastewater. Here we investigated the conditions which promote establishment of a suitable microbial community for performing nitritation when starting from regular sewage sludge. Reactors were operated in duplicate under different conditions (pH, temperature, and dilution rate) and were fed with 50 mM ammonium either as synthetic medium or as sludge digester supernatant. In all cases, stable nitritation could be achieved within 10 to 20 days after inoculation. Quantitative in situ hybridization analysis with group-specific fluorescent rRNA-targeted oligonucleotides (FISH) in the different reactors showed that nitrite-oxidizing bacteria of the genus Nitrospira were only active directly after inoculation with sewage sludge (up to 4 days and detectable up to 10 days). As demonstrated by quantitative FISH and restriction fragment length polymorphism (RFLP) analyses of the amoA gene (encoding the active-site subunit of the ammonium monooxygenase), the community of ammonia-oxidizing bacteria changed within the first 15 to 20 days from a more diverse set of populations consisting of members of the Nitrosomonas communis and Nitrosomonas oligotropha sublineages and the Nitrosomonas europaea-Nitrosomonas eutropha subgroup in the inoculated sludge to a smaller subset in the reactors. Reactors operated at 30°C and pH 7.5 contained reproducibly homogeneous communities dominated by one amoA RFLP type from the N. europaea-N, eutropha group. Duplicate reactors at pH 7.0 developed into diverse communities and showed transient population changes even within the ammonia oxidizer community. Reactors at pH 7.5 and 25°C formed communities that were indistinguishable by the applied FISH probes but differing in amoA RFLP types. Communities in reactors fed with sludge digester supernatant exhibited a... [ABSTRACT FROM AUTHOR]

Shows evidence for the existence of psychrophilic methanogenic communities in anoxic sediments of deep lakes. Methane production in sediment slurries; Rates of methane production from cellulose; Occurrence of the highest levels of methane production in the mesophilic or even thermophilic temperature range.

The membrane toxicity of linear alcohol ethoxylates (AEO/single reference compounds and technical mixtures) was investigated with an in vitro method based on time-resolved spectroscopy on energy-transducingmembranes. The nonspecific membrane perturbation of narcotic chemicals can be quantified by the degree of disturbance of buildup and relaxation of the membrane potential in membrane preparations of the purple bacterium Rhodobacter sphaeroides. The effect concentrations obtained for this narcotic effect correlated well with the results from various toxicity tests on whole organisms. In addition, the effect concentrations at the target site, the biological membrane, were derived from the nominal effect concentrations using membrane-water partitioncoefficients. The test set of linear AEO comprised compounds with analkyl chain length of 8 to 16 carbon units and 5 to 14 ethoxylate (EO) units covering more than four orders of magnitude of hydrophobicity (expressed as octanol-water partition coefficient). All AEO exhibited their toxic effect at concentrations well below the critical micelle concentration. When comparing aqueous effect concentrations, toxicity increased strongly with increasing length of the alkyl chain and showed a small parabolic dependence on the number of EO units with a maximum at eight EO units. With the toxic effect expressed in terms of membrane concentrations, all AEO exhibited similar activity in the concentration range typical for narcotic chemicals. The toxic membrane concentrations of AEO with 5 and >/=8 EO units were 200 and 60 mmol/kg lipid, which correspond to the critical body residues of nonpolarand polar narcotics in fish, respectively. In addition, the toxic effects of mixtures of AEO were measured and could be modeled as the sum of activities of the single constituents, confirming the concept ofconcentration additivity of compounds with the same mode of toxic action. [ABSTRACT FROM AUTHOR]

Presents a study to investigate predation of adhesive Psuedomonas putida mt2 by ciliate Tetrahymena sp., utilizing a percolated column system. Details on methodology used to conduct study; Indication of findings; Discussion on results.

Cell-free extracts of cellobiose-grown cells of the hyperthermophile Pyrococcus furiosus contain very high activities (19.8 U/mg) of a β-glucosidase. The cytoplasmic enzyme was purified 22-fold to apparent homogeneity, indicating that the enzyme comprises nearly 5% of the total cell protein. The native β-glucosidase has a molecular mass of 230 ±- 20 kDa, composed of 58 ±- 2-kDa subunits. The enzyme has a pI of 4.40. Thiol groups are not essential for activity, nor is the enzyme dependent on divalent cations or a high ionic strength. The enzyme shows optimum activity at pH 5.0 and 102-105 °; C. From Lineweaver-Burk plots, Vmax values of 470 U/mg and 700 U/mg were found for cellobiose (Km = 20 mM) and p-nitrophenyl-β-D-glucopyranoside (Km = 0.15 mM), respectively. The purified enzyme also exhibits high β-galactosidase activity and β-xylosidase activity, but shows no activity towards α-linked disaccharides or β-linked polymers, like cellulose. The purified β-glucosidase shows a remarkable thermostability with a half life of 85 h at 100 ° C and 13 h at 110 ° C. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) dehydrogenase was purified, both aerobically and anaerobically, to apparent homogeneity from Methanothrix soehngenii. The enzyme contained 18 ± 2 (n=6) mol Fe/mol and 2.0 ± 0.1 (n = 6) mol Ni/mol. Electron paramagnetic resonance (EPR) spectra of the aerobically purified CO dehydrogenase showed one sharp EPR signal at g = 2.014 with several characteristics of a [3Fe-45]1+ cluster. The integrated intensity of this signal was low, 0.03 S = ½ spin/αβ dimer. The 3Fe spectrum was not affected by incubation with CO or acetyl-coenzyme A, but could be reduced by dithionite. The spectrum of the reduced, aerobically purified enzyme showed complex EPR spectra, which had several properties typical of two [4Fe-4S]1+ clusters, whose S=½ spins weakly interacted by dipolar coupling. The integrated intensity was 0.1-0.2 spin/αβ dimer. The anaerobically isolated enzyme showed EPR spectra different from the reduced aerobically purified enzyme. Two major signals were apparent. One with g values of 2.05, 1.93 and 1.865, and an Em7.5 of -410 mV, which quantified to 0.9 S= ½ spin/αβ dimer. The other signal with g values of 1.997, 1.886 and 1.725, and an Em 7.5 of -230 mV gave 0.1 spin/αβ dimer. When the enzyme was incubated with its physiological substrate acetyl-coenzyme A. these two major signals disappeared. Incubation of the enzyme under CO atmosphere resulted in a partial disappearance of the spectral component with g = 1.997, 1.886, 1.725. Acetyl-coenzyme A/CO exchange activity, 35 nmol · min-1 · mg-1 protein, which corresponded to 7 mol CO exchanged min-1 mol-1 enzyme, could be detected in anaerobic enzyme preparations, but was absent in aerobic preparations. Carbon dioxide also exchanged with C-1 of acetyl-coenzyme A, but at a much lower rate than CO and to a much lower extent. [ABSTRACT FROM AUTHOR]

Studies the presentation of of evidence for the significance of heterogeneity in microbial populations for the subsurface transport of bacteria. Objective of the study; Methodology used in the study; Characterization of the cell surface; Development of a mechanistic interpretation based on energy interaction curves; Results of the study.

Focuses on a study which analyzed the Pseudomonas putida F1 chlorobenzene-degrading transconjugants, obtained from genes of the Pseudomonas sp. strain B13. Presence of the chlorocatechol (clc) gene cluster; Isolation of the plasmid deoxyribonucleic acid (DNA) from the B13 strain; Methodology used to conduct the study; Results of the study.