Assessment of brine discharges dispersion for sustainable management of SWRO plants on the South American Pacific coast.

Seawater desalination is one of the most feasible technologies for producing fresh water to address the water scarcity scenario worldwide. However, environmental concerns about the potential impact of brine discharge on marine ecosystems hinder or delay the development of desalination projects. In addition, scientific knowledge is lacking about the impact of brine discharges on the South America Pacific coast where desalination, is being developed. This paper presents the first monitoring results of brine discharge influence areas from seawater reverse osmosis desalination plants (SWRO) on the South America Pacific coast, using Chile as case study. Our results indicate that the combination of favorable oceanographic conditions and diffusers, results in the rapid dilution of brine discharge on coastal ecosystems; showing a faster dilution than other SWRO plants in other regions, such as Mediterranean or Arabian Gulf, with similar production characteristics. Also, the increase in salinity over the natural salinity in the brine-discharge-affected area was <5 % in a radius of <100 m from the discharge points. Further, according to the published literature and on our monitoring results, we propose a number of considerations (environmental regulation, best scientifically tested measures, environmental requirements) to achieve a long-term sustainable desalination operation.

Ecotoxicological response surface analysis of salt and pH in textile effluent on Bacillus subtilis and Lactuca sativa.

Textile effluents, although their composition can vary considerably, typically contain high levels of dissolved salts and exhibit wide variations in pH. Ecotoxicological studies regarding the effects of these parameters, however, have been limited owing to the need for sensitive and easy-to-handle bioindicators that require low amounts of sampling, are cost-effective, time-efficient, and ethically endorsed. This kind of study, additionally, demands robust multi-factorial statistical designs that can accurately characterize the individual and combined relationship between variables. In this research, Response Surface Methodology (RSM) was used to calculate the individual and interaction effects of NaCl concentration and pH value of a Simulated Textile Effluent (STE) on the development rate (DR) of the bioindicators: Bacillus subtilis bacteria and Lactuca sativa lettuce. The results demonstrated that the bioindicators were sensitive to both NaCl and pH factors, where the relative sensitivity relationship was B. subtilis > L. sativa. The quadratic equations generated in the experiments indicated that increased concentrations of 50-250 mg L-1 of NaCl caused a perturbance of 1.40%-34.40% on the DR of B. subtilis and 0.50%-12.30% on L. sativa. The pH factor at values of 3-11 caused an alteration of 27.00%-64.78% on the DR of the B. subtilis and 51.37%-37.37% on the L. sativa. These findings suggest that the selected bioindicators could serve as effective tools to assess the ecotoxicological effects of textile effluents on different ecological systems, and the RSM was an excellent tool to consider the ecotoxicological effects of the parameters and to describe the behavior of the results. In conclusion, the NaCl and pH factors may be responsible for disrupting different ecosystems, causing imbalances in their biodiversity and biomass. Before discharge or reuse, it is suggested to remove salts and neutralize pH from textile effluents and, mostly, develop novel, eco-friendlier textile processing techniques.

Dynamics of changes in cadmium levels in environmental objects and its impact on the bio-elemental composition of living organisms.

As a result of intensive anthropogenic impact in the biosphere there is a rapid process of accumulation of heavy metal salts. They have led to the aggravation of problems associated with the pollution of ecosystems and basic food products of plant and animal origin. Environmental pollution by these compounds is caused by their persistence in environmental objects, migration ability, accumulation by plants. This contributes to their accumulation in the human environment. A number of studies have shown that heavy metals have mutagenic, toxic effects and affect the intensity of biochemical processes. Therefore, the presence of heavy metals in the environment is extremely undesirable. Moreover, the ecological state of the environment is directly related to changes in the human internal environment. Deficiency or excess of certain bioelements in soils and drinking water or non-compliance with its stable chemical composition causes the development of dysmicroelementosis. The ecological situation of the Carpathian region is closely related to the state of soils and water resources. In this regard, it is advisable to study and control the level of cadmium compounds in the environment of the region. The study of the effect of cadmium intoxication on the macro- and microelement composition of the brain and myocardium of experimental animals is also worthwhile. Materials and methods. Soils and drinking water of the plain, foothill and mountainous zones of the region, as well as organs and tissues of experimental animals served as the object of research. Cadmium levels in drinking water and myocardial tissues and brain of experimental animals have been measured by atomic absorption spectroscopy. Results and discussion. The study of soils in the Prykarpattia region has revealed an increase in the toxic element cadmium. Its content is 1.1-1.5 times higher than background levels. The analysis of drinking water allowed to establish that a significant number of people living in the plain and foothill zone of the region consume water with a high content of cadmium. The main stages of cadmium intake and accumulation in plants have been analyzed. Significant disorders in the body of experimental animals under conditions of excessive intake of cadmium compounds have been revealed. It was accompanied by the accumulation of cadmium in the myocardium and brain, on the background of redistribution of vital macronutrients calcium and magnesium along with micronutrients copper and zinc. Thus, excessive intake of cadmium salts causes the development of dysmicroelementosis, which is accompanied by a violation of the homeostasis of a living organism. It is suggested to conduct continuous monitoring of the level of toxicants in the ecosystem as an integral component of environmental monitoring.

Inhibition of mycelial growth, conidial germination, and Botrytis cinerea Pers: Fr colonization in begonia with biocompatible products

This study evaluated the effects of potassium and sodium carbonate and bicarbonate, Bacillus subtilis (Cohn, 1872) QST-713, Bacillus pumilus (Meyer & Gottheil, 1901) QST-2808, and crude and roasted coffee oils on the inhibition of mycelial growth and conidial germination in Botrytis cinerea Pers.: Fr and the colonization of begonia (Begonia elatior Hort. ex Steud) leaf discs by B. cinerea inoculated before, simultaneously and after with these alternative products. The assays were carried out using the Baladin begonia cultivar. The inhibition of B. cinerea mycelial growth and conidial germination was proportional to increases in the concentration of all the products. The inhibition of conidial germination was directly proportional to the concentrations of B. pumilus QST-2808 and B. subtilis QST-713. Coffee oils were less efficient in inhibiting germination than the other products. The crude and roasted coffee oils, potassium and sodium carbonates and bicarbonates, and B. pumilus and B. subtilis sprayed 24 h before, simultaneously, or 24 h after pathogen inoculation inhibited the colonization of begonia leaf discs by B. cinerea. The positive results for the suppression of B. cinerea by the alternative products tested herein merit scrutiny. There is a pressing need to evaluate these products in the management of gray mold, as the severity of this disease is usually high under favorable conditions in greenhouses.

Cell wall stabilization and calcium absorption on mango fruit treated with a quarantine hot water treatment combined with calcium salts and stored at chilling temperature.

Hot water treatment (HT) induces chilling injury (CI) tolerance in mango, but prolonged exposure to HT causes softening. In this sense, calcium salts stabilize the cell wall. Nevertheless, there is little information on the effect of HT combined with calcium salts (HT-Ca) on calcium absorption and cell wall stability during storage of mango at CI temperature. We evaluated the effect of quarantine HT in combination with calcium chloride (CaCl2 ), calcium citrate (CaCit), or calcium lactate (CaLac) on calcium absorption, CI tolerance, and cell wall stabilization. HT and HT-CaCl2 had the lowest CI development. HT increased firmness loss and electrolyte leakage, and HT-Ca counteracted this effect. Overall, HT-Ca treatments had a similar effect on the cell wall degrading enzymes. HT-CaCl2 was the best treatment and did not present alterations on the epicuticular wax as observed on HT. HT-CaCl2 is a useful technology to stabilize cell wall and preserve mango during chilling storage. PRACTICAL APPLICATIONS: The addition of calcium salts in an established hot water quarantine procedure for mango exportation represents a viable alternative to counteract the negative effects of this thermal treatment upon cell microstructure, maintaining its positive effect of tolerance to chilling injury. In this sense, mango producers and packers can use a HT-CaCl2 treatment to reduce the presence of chilling injury and extent the fruit shelf life and improve its commercialization. Furthermore, technical and infrastructure changes are not necessary for the packaging chain.

Prokaryotic diversity and community composition in the Salar de Uyuni, a large scale, chaotropic salt flat.

Salar de Uyuni (SdU), with a geological history that reflects 50 000 years of climate change, is the largest hypersaline salt flat on Earth and is estimated to be the biggest lithium reservoir in the world. Its salinity reaches saturation levels for NaCl, a kosmotropic salt, and high concentrations of MgCL2 and LiCl, both salts considered important chaotrophic stressors. In addition, extreme temperatures, anoxic conditions, high UV irradiance, high albedo and extremely low concentrations of phosphorous, make SdU a unique natural extreme environment in which to contrast hypotheses about limiting factors of life diversification. Geophysical studies of brines from different sampling stations show that water activity is rather constant along SdU. Geochemical measurements show significant differences in magnesium concentration, ranging from 0.2 to 2M. This work analyses the prokaryotic diversity and community structure at four SdU sampling stations, selected according to their location and ionic composition. Prokaryotic communities were composed of both Archaea (with members of the classes Halobacteria, Thermoplasmata and Nanohaloarchaea, from the Euryarchaeota and Nanohaloarcheota phyla respectively) and Bacteria (mainly belonging to Bacteroidetes and Proteobacteria phyla). The important differences in composition of microbial communities inversely correlate with Mg2+ concentration, suggesting that prokaryotic diversity at SdU is chaotropic dependent.

Biofilm-producing ability of Listeria monocytogenes isolates from Brazilian cheese processing plants.

The persistence of Listeria monocytogenes in food industry environments has been associated to the ability of specific isolates to produce biofilms. This study aimed to evaluate the biofilm production of 85 L. monocytogenes strains previously isolated from samples of cheese, brine and the environment of two cheese processing plants located in São Paulo, Brazil. The L. monocytogenes isolates belonged to serotypes 4b, 1/2b and 1/2c, yielded 30 different pulsotypes by pulsed-field gel electrophoresis (PFGE), and were submitted to biofilm-formation assays on polystyrene microplates and stainless steel coupons incubated statically at 35±0.5°C for 48h. All isolates from different sources showed ability to produce biofilms on polystyrene microplates, from which 21 (24.7%) also produced biofilms on stainless steel. Four isolates (4.7%) belonging to four different pulsotypes were classified as strong biofilms-producers on polystyrene microplates, while isolates belonging to four pulsotypes previously evaluated as persistent had weak or moderate ability to produce biofilms on polystyrene microplates. No relationship between the serotypes or pulsotypes and their biofilm-forming ability was observed. This study highlights the high variability in the biofilm production among L. monocytogenes strains collected from cheese and cheese-production environment, also indicating that strong biofilm-formation ability is not a key factor for persistence of specific isolates in cheese processing plants.

Unsymmetrically substituted imidazolium salts: synthesis, characterization and antimicrobial activity

ABSTRACT Unsymmetrically substituted imidazolium salts were synthesized and characterized using 1H-NMR and 13C-NMR. The antimicrobial activities of the salts were evaluated using the agar-well diffusion method against 14 bacteria and five yeasts. The minimal inhibitory concentrations (MIC) against seven bacteria and one yeast were also determined. Among the test compounds applied, 1, 2, 3, 6 and 11 showed activities against Micrococcus luteus ATCC 9341, Staphylococcus aureus ATCC 25923, Staphylococcus epidermidis ATCC 12228, Bacilllus cereus ATCC 11778, Bacillus subtilis ATCC 6633, Bacillus thuringiensis, Listeria monocytogenes ATCC 19112 and Candida trophicalis. However, compounds 1, 2 and 3 showed the highest antimicrobial activities against Micrococcus luteus ATCC 9341, Stapylococcus aureus ATCC 25923, Staphylococcus epidermidis ATCC 12228, Bacilllus cereus ATCC 11778 and Bacillus subtilis ATCC 6633 with inhibition zones of 14-20 mm. In addition, compound 6 have only demonstrated activities against Candida trophicalis while compounds 4, 5, 7, 8, 9, 10, 12, 13 and 14 had no effect on test microorganisms.

Characterization of fine mode atmospheric aerosols by Raman microscopy and diffuse reflectance FTIR.

A combination of Raman microscopy and diffuse reflectance Fourier transform infrared spectroscopy (FTIR) has been used for the characterization of fine mode (<1 µm) tropospheric aerosols. Peak fitting was used to identify five overlapping bands in the Raman spectra. These bands have been identified as due to combustion generated carbon soot as well as large molecular organic carbon species. The fwhm of the D band at 1400 cm(-1) as well as the ratio of intensities of the D3 band at 1550 cm(-1) to the G band at 1580 cm(-1) can serve as a measure of the aerosol organic carbon content. Raman microscopy combined with spectral mapping capabilities was used to investigate the composition of the fine mode aerosols at the particle level, allowing for the direct determination of aerosol mixing state. Results showed that the fine aerosols were predominately internally mixed particles composed of carbon soot coated with molecular organic carbon species. Characterization of the aerosols by diffuse reflectance FTIR showed that the major organic carbon species were polycarboxylates and polysaccharide-like species typical of humic-like substances (HULIS).

Impacts of urbanization on groundwater hydrodynamics and hydrochemistry of the Toluca Valley aquifer (Mexico).

The Toluca Valley is located on the high plains of Mexico, where there are significant industrial zones and large populations. Water needs are almost exclusively met by groundwater, which has brought about intense exploitation of the aquifer and indication of some contamination. The present study investigates the effect of urbanization, related to industrialization of the region, on groundwater in the central portion of the Toluca Valley aquifer--a zone with high population density and where the largest industrial park is located. A general decline in the groundwater level has been found over the years, at a rate of as much as 2.5 m/year. The appearance of a large drawdown cone was identified, indicating changes in the direction of groundwater flow. Also identified was the presence of several ground fissures, the location of which coincided with the drawdown cone. In hydrochemical terms, the water type is sodium-magnesium bicarbonate and this characteristic has not changed over time, although it has been possible to detect the presence of larger quantities of sulfates (up to 117 mg/L) and nitrates (up to 47 mg/L) in recent years, likely associated with contamination from industrial and urban wastewater. Factor analysis made it possible to identify ions that would characterize natural processes involving the acquisition of salts (HCO3 (-), Na(+), Mg(2+), and Si), as well as anthropic activities (SO4 (2-), NO3 (-), Cl(-), Ca(2+), and K(+)).

Black soiling of an architectural limestone during two-year term exposure to urban air in the city of Granada (S Spain).

A two-year term aging test was carried out on a building limestone under different urban conditions in the city of Granada (Southern Spain) to assess its Cultural Heritage sustainability. For this purpose stone tablets were placed vertically at four sites with contrasting local pollution micro-environments and exposure conditions (rain-sheltered and unsheltered). The back (rain-sheltered) and the front (rain-unsheltered) faces of the stone tablets were studied for each site. The soiling process (surface blackening) was monitored through lightness (ΔL*) and chroma changes (ΔC*). Additionally atmospheric particles deposited on the stone surfaces and on PM10 filters during the exposure time were studied through a multianalytical approach including scanning electron microscopy (SEM-EDX), transmission electron microscopy (TEM) and micro-Raman spectroscopy. The identified atmospheric particles (responsible for stone soiling) were mainly soot and soil dust particles; also fly ash and aged salt particles were found. The soiling process was related to surface texture, exposure conditions and proximity to dense traffic streets. On the front faces of all stones, black soiling and surface roughness promoted by differential erosion between micritic and sparitic calcite were noticed. Moreover, it was found that surface roughness enhanced a feedback process that triggers further black soiling. The calculated effective area coverage (EAC) by light absorbing dust ranged from 10.2 to 20.4%, exceeding by far the established value of 2% EAC (limit perceptible to the human eye). Soiling coefficients (SC) were estimated based on square-root and bounded exponential fittings. Estimated black carbon (BC) concentration resulted in relatively similar SC for all studied sites and thus predicts the soiling process better than using particulate matter (PM10) concentration.

Microbial biogeography of six salt lakes in Inner Mongolia, China, and a salt lake in Argentina.

We used cultivation-independent methods to investigate the prokaryotic biogeography of the water column in six salt lakes in Inner Mongolia, China, and a salt lake in Argentina. These lakes had different salt compositions and pH values and were at variable geographic distances, on both local and intercontinental scales, which allowed us to explore the microbial community composition within the context of both contemporary environmental conditions and geographic distance. Fourteen 16S rRNA gene clone libraries were constructed, and over 200 16S rRNA gene sequences were obtained. These sequences were used to construct biotic similarity matrices, which were used in combination with environmental similarity matrices and a distance matrix in the Mantel test to discover which factors significantly influenced biotic similarity. We showed that archaeal biogeography was influenced by contemporary environmental factors alone (Na+, CO3(2-), and HCO3(-) ion concentrations; pH; and temperature). Bacterial biogeography was influenced both by contemporary environmental factors (Na+, Mg2+, and HCO3(-) ion concentrations and pH) and by geographic distance.

Influência dos teores de caseinato de cálcio e sais fundentes nas características sensoriais e físico-químicas de requeijões cremosos / nfluence of calcium caseinato and melting salt content in the sensorial and physical-chemical characteristics of cream cheese

O requeijão cremoso teve um aumento significativo da sua produção nos últimos anos, e tornou-se um produto de destaque nos hábitos alimentares dos consumidores. Concomitantemente a este aumento na produção, cresceu o uso de proteínas do soro como ingrediente em alimentos lácteos e não lácteos, sendo uma alternativa menos onerosa às indústrias. O objetivo deste trabalho foi desenvolver 12 formulações de requeijão utilizando soro de queijo, caseinato de cálcio e sal fundente e avaliar suas características físico-químicas. Também foram avaliados os atributos sensoriais: odor, cor, textura, qualidade global, aroma e sabor. Os resultados observados mostraram que as características físico-químicas das formulações foram semelhantes às da amostra comercial e adequadas segundo a legislação, indicando que é possível a fabricação de requeijão utilizando soro de queijo como base. A utilização do caseinato de cálcio ajudou na manutenção das propriedades físico-químicas do produto. As formulações utilizando soro de leite apresentaram boa aceitação. Os resultados confirmam as vantagens nutricionais que podem ser oferecidas ao consumidor quando se utiliza um subproduto da indústria láctea, gerando um produto de alto valor agregado e interessante nutricionalmente.

The cream cheese had a significant increase of its production in last ten years, and became a product of prominence in the alimentary habits of the consumers. Concomitantly to increase the production, the use of the serum protein also grew as ingredient in milky and not milky foods, being a less onerous alternative to the industries. The objective of this work was to develop twelve cream cheese formularizations using cheese serum, calcium caseinato and melting salt, to evaluate its physical-chemical characteristics and to compare them it the current law and with a commercial product. Also the sensorial attributes had been evaluated: odour, color, texture, global quality, aroma and flavor. The observed results had shown that the physical-chemical characteristics of the formularizations had been similar to the ones of the commercial sample and adjusted according to legislation, indicating that the cream cheese manufacture is possible using cheese serum as base. The use of the calcium caseinato influence the maintenance of the physical-chemical properties of the product. The formularizations using milk serum had presented good acceptance in relation to the commercial mark. The results confirm the nutricional advantages that can be offered the consumer when a by-product of the milked industry is used, generating a product of high aggregate and interesting nutricional value.

Influência dos teores de caseinato de cálcio e sais fundentes nas características sensoriais e físico-químicas de requeijões cremosos / nfluence of calcium caseinato and melting salt content in the sensorial and physical-chemical characteristics of cream cheese

O requeijão cremoso teve um aumento significativo da sua produção nos últimos anos, e tornou-se um produto de destaque nos hábitos alimentares dos consumidores. Concomitantemente a este aumento na produção, cresceu o uso de proteínas do soro como ingrediente em alimentos lácteos e não lácteos, sendo uma alternativa menos onerosa às indústrias. O objetivo deste trabalho foi desenvolver 12 formulações de requeijão utilizando soro de queijo, caseinato de cálcio e sal fundente e avaliar suas características físico-químicas. Também foram avaliados os atributos sensoriais: odor, cor, textura, qualidade global, aroma e sabor. Os resultados observados mostraram que as características físico-químicas das formulações foram semelhantes às da amostra comercial e adequadas segundo a legislação, indicando que é possível a fabricação de requeijão utilizando soro de queijo como base. A utilização do caseinato de cálcio ajudou na manutenção das propriedades físico-químicas do produto. As formulações utilizando soro de leite apresentaram boa aceitação. Os resultados confirmam as vantagens nutricionais que podem ser oferecidas ao consumidor quando se utiliza um subproduto da indústria láctea, gerando um produto de alto valor agregado e interessante nutricionalmente.(AU)

The cream cheese had a significant increase of its production in last ten years, and became a product of prominence in the alimentary habits of the consumers. Concomitantly to increase the production, the use of the serum protein also grew as ingredient in milky and not milky foods, being a less onerous alternative to the industries. The objective of this work was to develop twelve cream cheese formularizations using cheese serum, calcium caseinato and melting salt, to evaluate its physical-chemical characteristics and to compare them it the current law and with a commercial product. Also the sensorial attributes had been evaluated: odour, color, texture, global quality, aroma and flavor. The observed results had shown that the physical-chemical characteristics of the formularizations had been similar to the ones of the commercial sample and adjusted according to legislation, indicating that the cream cheese manufacture is possible using cheese serum as base. The use of the calcium caseinato influence the maintenance of the physical-chemical properties of the product. The formularizations using milk serum had presented good acceptance in relation to the commercial mark. The results confirm the nutricional advantages that can be offered the consumer when a by-product of the milked industry is used, generating a product of high aggregate and interesting nutricional value.(AU)

Seasonal seawater temperature as the major determinant for populations of culturable bacteria in the sediments of an intact mangrove in an arid region.

Mangroves are highly productive marine ecosystems where bacteria (culturable and non-culturable) actively participate in biomineralization of organic matter and biotransformation of minerals. This study explores spatial and seasonal fluctuations of culturable heterotrophic bacteria and Vibrio spp. in the sediments of an intact mangrove ecosystem and determines the dominant environmental factors that govern these fluctuations. Sediment samples were collected monthly from three stations in the mangroves of Laguna de Balandra, Baja California Sur, Mexico, through an annual cycle. Physicochemical parameters included seawater temperature, salinity, and concentration of dissolved oxygen. Viable counts of culturable heterotrophic bacteria and Vibrio spp. were made. In one sample (March 2003), nutrient concentrations (ammonium, nitrites, nitrates, and phosphates), organic matter, pH and sediment texture were also determined. General cluster analyses, analysis of variance of specific variables, and several principal component analyses demonstrated that seawater temperature is the principal determinant of seasonal distribution of culturable heterotrophic bacteria and Vibrio spp. in mangrove sediments. Soil texture, concentration of nutrients, and organic matter concentration contribute to heterogenicity to a lesser extent. A large spatial variation in bacterial populations was observed over short distances ( approximately 1 m) in sampling areas within the same site. These analyses show that the culturable bacterial distribution in sediments of mangroves has high spatial and temporal heterogeneity.

Actividad biológica y enzimática en suelos afectados por sales del Alto Valle de Río Negro y Neuquén / Biological and enzymatic activities in salts affected soils from Alto Valle de Río Negro and Neuquén

En el presente trabajo se estudiaron los cambios que provocó el lavado de cinco suelos afectados por sales sobre la actividad biológica (número de bacterias g-1y producción de CO2) y enzimática (catalasa, deshidrogenasa, ureasa y fosfotriesterasa) de los mismos. El lavado disminuyó la conductividad eléctrica (CE) y modificó el tipo de sales dominantes en los suelos. La producción de CO2 y la actividad de la fosfotriesterasa fue significativamente mayor (p<0,05) en un suelo lavado (Torrifluventes Típicos Centenario); el incremento fue del 88% y 71%, respectivamente. Los resultados demostraron que la disminución de la salinidad por lavado no ocasionó comportamientos significativamente diferentes, en la mayoría de los parámetros bióticos estudiados, bajo las condiciones en que se realizó este estudio.

Changes in the biological activity (number of bacteria g-1and CO2 production) and in the enzymatic activity (catalase, deshidrogenase, urease and phosphotriesterase) caused by the leaching of five soils affected by salts have been studied. The leaching decreased the electric conductivity (CE) and modified the type of dominant salts in the soils. Production of CO2and the activity of the phosphotriesterase was significantly higher (p<0,05) in a leached soil (Torrifluventes Typical Centennial); the increment were 88% and 71%, respectively. The results showed that the decrease of the salinity by leaching did not produce significantly different results in most of the biotic parameters analised.

[Biological and enzymatic activities in salt-affected soils from Alto Valle de Río Negro and Neuquén]. / Actividad biológica y enzimática en suelos afectados por sales del Alto Valle de Río Negro y Neuquén.

Changes in the biological activity (number of bacteria g(-1) and CO2 production) and in the enzymatic activity (catalase, deshydrogenase, urease and phosphotriesterase) caused by the leaching of five soils affected by salts have been studied. The leaching decreased the electric conductivity (CE) and modified the type of dominant salts in the soils. Production of CO2 and the activity of the phosphotriesterase was significantly higher (p<0.05) in a leached soil (Torrifluventes Typical Centennial); the increment were 88% and 71%, respectively. The results showed that the decrease of the salinity by leaching did not produce significantly different results in most of the biotic parameters analysed.

Interference in the Limulus amebocyte lysate assay for endotoxin determination in peritoneal dialysis fluids and concentrates for hemodialysis.

The interference of the saline concentration of fluids for peritoneal dialysis and concentrates for hemodialysis on the Limulus amebocyte lysate (LAL) assay for endotoxins was investigated. The experiments were carried out individually with each substance that compose fluids for hemodialysis, to determine the possible inhibition or enhancement effects that they could cause on the LAL assay. The compositions were also assayed to investigate the possibility of synergistic effect. They were assayed by the gel-clot method from two different suppliers, and the samples that showed inhibition effect were also assayed by the chromogenic method. The samples were analysed at successive dilutions, with different LAL sensitivities, to satisfy the endotoxin limits of 5 EU/ml for the concentrate and 0.25 EU/ml for the fluid for dialysis peritoneal. The results showed that the major interference on the gel-clot assay occurs in presence of acetic acid and in concentrates containing acid acetic, even the pH being adjusted between 6.5 and 7.5. However, the test, after an adequate dilution, could be validating for all samples. Chromogenic test can be used for peritoneal dialysis fluids considering a limit of 0.25 EU/ml and sample dilution of eight times, but it cannot be used for concentrates for hemodialysis without further dilution. Considering the results and that the chromogenic is a more time-consuming method, endotoxins in fluids for hemodialysis can be satisfactorily assayed by the gel-clot method.

Isolation of Cry1Ab protein mutants of Bacillus thuringiensis by a highly efficient PCR site-directed mutagenesis system.

A site-directed mutagenesis method was designed and used to create Cry1Ab mutant proteins in two of the five highly conserved blocks present in the Cry protein family. Region 1 comprises the central alpha-helix 5 of domain I and has been implicated in the pore formation activity of the toxin. Substitution of arginine by serine at position 173 (R173S) affects neither structural integrity nor toxicity. Region 2 comprises the major part of the domain I/domain II interface, characterized by the presence of numerous hydrogen bonds and electrostatic interactions. Mutations in the salt bridge formed by aspartic acid 242 and arginine 265 (D242N, D242C, R265C, and D242C/R265C) resulted in structurally unstable mutant proteins as is shown by their increased protease sensitivity and lack of biological activity.

The evaporation path of seawater and the coprecipitation of Br- and K+ with halite.

Brines and salt were sampled at the Morton Bahamas solar salt production facility on Great Inagua Island in the Bahamas. The brines were analyzed by ion chromatography to define more precisely than heretofore the evaporation path of seawater to the end of the halite facies. At Inagua, calcium carbonate begins to precipitate at a brine concentration factor of 1.8 times that of seawater. Gypsum begins to precipitate at a brine concentration of 3.8 times seawater, and halite at a concentration factor of 10.6. Three of the most concentrated brines from Inagua (40 times seawater) were evaporated further in the laboratory. Magnesium sulfate first precipitated at brine concentrations about 70 times those of seawater, and potassium-bearing phases began to precipitate for these brines at concentrations greater than 90 times those of seawater. The distribution of coefficients of Br- and K+ between brines and halite were determined by combining analytical data for the Inagua brines with measurements of the Br- and K+ content of halites from Inagua and of halite which had precipitated from Inagua brines during storage. The observed average value of DBr- is 0.032, in good agreement with some of the previous measurements. The measured values of DK+ are highly variable (0.001 to 0.021); DK+ for halite precipitated early in the halite facies is in the vicinity of 0.015.