Salty Environment Research Articles

Multiple-image treatment of induced charges in Monte Carlo simulations of electrolytes near a spherical dielectric interface

The polarization-induced charges of a dielectric sphere are studied for charged colloidal systems in electrolyte solutions with a primitive model. The method of constructing multiple-image charges is used to approximate the polarization potential of a microion outside the sphere; it is based on a numerical discretization of the potential's analytical integral representation, and can systematically approximate the exact potential with desired accuracy by varyiation of the number of point images. Different aspects of the image effects are then investigated by Monte Carlo simulations for several colloidal systems, in both salt-free and salty environments. Furthermore, we studied the influence of discrete surface charges of different valences, and demonstrate that the polarization charges can significantly strengthen charge reversal for the colloid-microion complex, especially for multivalent interfacial ions.

Intracellular pathogens: living in an extreme environment

The phylogenetic tree segregates into three major groups, which probably descended from a common ancestor: the bacteria, the archaea, and the eucarya (1–3). While bacteria and archaea lack a true nucleus and intracellular organelles, eucarya possess these. The origin of the ancestor remains elusive, but it emerged about 4 billion years ago. The bacteria probably started life 3.5 billion years ago and eukaryotes emerged 1.75 billion years thereafter. Sometime in between archaea appeared. Eukaryotes began as unicellular organisms but soon also developed multicellular forms. Bacteria and archaea had sufficient time to exploit all niches of the abiotic environment, ranging from ice cold glacial lakes to fiery geysers – from the highest mountain peaks to the deepest sea beds. They also quickly developed forms of mutualism by forming colonies composed of mixed populations. With the evolution of eucarya, new environments could be exploited. Today prokaryotes are the most prevalent form of life on earth, making up the majority of our biomass. It has been estimated that more than 10 prokaryotic organisms live on our globe. Thus, archaea and bacteria are far more prevalent than eucarya. Even human beings comprise more prokaryotic cells than mammalian cells, which range on the order of 10 human cells and 10 prokaryotes mostly concentrated in our intestinal system (4–7).

GIS-based modeling of potential yield distributions for different oat varieties in China

Cultivation of the common oat ( Avena sativa L.) and the naked oat ( Avena nuda L.) can be highly productive in many types of environments because these species are tolerant to infertile, dry and salty environments. In this study, we modeled the distribution of potential yields for different varieties of oat in China based on GIS assessments. We analyzed the yield of three oat varieties under different environmental conditions and created a model of factors significantly correlated with yield. Stepwise regression models were constructed for each oat variety, and the potential yield distributions were calculated for each variety. Correlating oat variety yield with environmental factors showed that precipitation and soil nutrition content were the most important factors in oat production. Precipitation and soil nutrition during the month of April were positively correlated with yield, while temperature and wind speed in July were negatively correlated with yield. The common oat variety “Qingyj444” was capable of producing a fresh grass yield of 30,000 kg/hm 2 in western Sichuan, the southwest of Gansu, and certain parts of Qinghai and Heilongjiang province. The naked oat varieties “Bayou3” and “Pin5” produced high yields of 3000 kg/hm 2 in Heilongjiang, the regions north of Shanxi, east of Neimenggu and the southern Gansu province, areas with high quality rain and soil nutrition conditions. We constructed a “China Crop Mapping Decision System” based on our findings, and this system is accessible through the internet and will facilitate informed agricultural decision-making.

Test and Study on Impact of Corrosion on Bond Force between Steel and Concrete

The corrosion of steel will have a bad impact on the safety of reinforced concrete structure. In severe cases, it may even be disastrous. In order to understand the impact of steel corrosion on the structure, tests are carried out to study corrosion and expansion rules of steel bars as well as the impact rules of corrosion on bond force between steel and concrete. The results show that wet and salty environment will result in steel corrosion; relatively minor corrosion will not cause expansion cracks of protection layers; when steel rust to a certain extent, it will cause cracks along the protection layer; when there exists minor corrosion in steel and the protection layer does not have expansion cracks, the bond force is still large and rapidly decreases as the corrosion rate increases.

Halophilic archaea in the human intestinal mucosa

The human gastrointestinal tract microbiota, despite its key roles in health and disease, remains a diverse, variable and poorly understood entity. Current surveys reveal a multitude of undefined bacterial taxa and a low diversity of methanogenic archaea. In an analysis of the microbiota in colonic mucosal biopsies from patients with inflammatory bowel disease we found 16S rDNA sequences representing a phylogenetically rich diversity of halophilic archaea from the Halobacteriaceae (haloarchaea), including novel phylotypes. As the human colon is not considered a salty environment and haloarchaea are described as extreme halophiles, we evaluated and further discarded the possibility that these sequences originated from pre-colonoscopy saline lavage solutions. Furthermore, aerobic enrichment cultures prepared from a patient biopsy at low salinity (2.5% NaCl) yielded haloarchaeal sequence types. Microscopic observation after fluorescence in situ hybridization provided evidence of the presence of viable archaeal cells in these cultures. These results prove the survival of haloarchaea in the digestive system and suggest that they may be members of the mucosal microbiota, even if present in low numbers in comparison with methanogenic archaea. Investigation of a potential physiological basis of this association may lead to new insights into gastrointestinal health and disease.

Molecular cloning and characterization of STL1 gene of Debaryomyces hansenii

Debaryomyces hansenii is often found in salty environments. This yeast species is not only halotolerant, but also halophilic. Its genome sequence is known completely, but the mechanisms behind its halotolerance are poorly understood. It was compared to the STL1 protein sequence of Saccharomyces cerevisiaeagainst the translated sequence from the D. hansenii genome sequence database released by Genolevure. An ORF (DEHA0E01122g) was found with 54% homology and 39% identity with Stl1p from S. cerevisiae. DhSTL1 was heterologously expressed successfully in a S. cerevisiae (BY4741) wild type and in another strain lacking its own system for the glycerol transport (STL1) gene. The DhSTL1 gene in transformed S. cerevisiae strains showed a slight but significant difference in the doubling times in growth curves obtained in liquid YNB-ura medium, with glycerol as carbon source. DhSTL1 gene in transformed stl1 yeast strain showed phenotype growth at pH 7.5 under salt stress conditions (glucose as carbon source). The kinetic parameters of transport and glycerol accumulation conferred by DhSTL1 in the S. cerevisiae transformant strains did not show significant differences. An increase in the transcript level of DhSTL1 gene in the presence of saline stress at pH 5.6; whereas, at 7.5 pH, it was expressed in all evaluated conditions. Key words: Debaryomyces hansenii, glycerol, transport, salt tolerance.

Silica Precipitation in Acidic Solutions: Mechanism, pH Effect, and Salt Effect

This study is the first to show that silica precipitation under very acidic conditions ([HCl] = 2-8 M) proceeds through two distinct steps. First, the monomeric form of silica is quickly depleted from solution as it polymerizes to form primary particles approximately 5 nm in diameter. Second, the primary particles formed then flocculate. A modified Smoluchowski equation that incorporates a geometric population balance accurately describes the exponential growth of silica flocs. Variation of the HCl concentration between 2 and 8 M further showed that polymerization to form primary particles and subsequent particle flocculation become exponentially faster with increasing acid concentration. The effect of salt was also studied by adding 1 M chloride salts to the solutions; it was found that salts accelerated both particle formation and growth rates in the order: AlCl(3) > CaCl(2) > MgCl(2) > NaCl > CsCl > no salt. It was also found that ionic strength, over cation identity, determines silica polymerization and particle flocculation rates. This research reveals that precipitation of silica products from acid dissolution of minerals can be studied apart from the mineral dissolution process. Thus, silica product precipitation from mineral acidization follows a two-step process--formation of 5 nm primary particles followed by particle flocculation--which becomes exponentially faster with increasing HCl concentration and with salts accelerating the process in the above order. This result has implications for any study of acid dissolution of aluminosilicate or silicate material. In particular, the findings are applicable to the process of acidizing oil-containing rock formations, a common practice of the petroleum industry where silica dissolution products encounter a low-pH, salty environment within the oil well.

Methanobacterium petrolearium sp. nov. and Methanobacterium ferruginis sp. nov., mesophilic methanogens isolated from salty environments

Two methane-producing archaea, designated Mic5c12(T) and Mic6c05(T), were isolated from sludge deposited in a crude oil storage tank and a tubercle on the interior of a pipe transporting natural gas-containing brine, respectively. The isolates were Gram-staining-variable, non-motile rods and grew only on H(2)/CO(2). Strain Mic6c05(T) produced methane from some alcohols without showing any growth; strain Mic5c12(T) did not utilize alcohols. The optimum growth conditions for strain Mic5c12(T) were 35 °C, pH 6.5 and 0-0.68 M NaCl and for strain Mic6c05(T) were 40 °C, pH 6.0-7.5 and 0.34 M NaCl. Strain Mic5c12(T) was halotolerant and strain Mic6c05(T) was halophilic. Comparative 16S rRNA gene sequence analysis revealed that strains Mic5c12(T) and Mic6c05(T) belonged to the genus Methanobacterium and their closest relative was Methanobacterium subterraneum A8p(T) (97.3 and 97.9 % 16S rRNA gene sequence similarity, respectively). The findings from the 16S rRNA gene sequence analyses were supported by analysis of McrA, the alpha subunit of methyl-coenzyme M reductase. On the basis of phylogenetic analyses and phenotypic characteristics, two novel species are proposed, Methanobacterium petrolearium sp. nov. and Methanobacterium ferruginis sp. nov., with type strains Mic5c12(T) (=NBRC 105198(T) =DSM 22353(T)) and Mic6c05(T) (=NBRC 105197(T) =DSM 21974(T)), respectively.

FATIGUE STRENGTH OF LOAD-CARRYING TYPE AND NON LOAD-CARRYING TYPE FILLET WELDED JOINTS USED AUSTENITIC STAINLESS STEEL (FATIGUE STRENGTH EFFECTED BY CORROSIVE ENVIRONMENT)

This paper showed the fatigue strength of load-carrying type and non load-carrying type fillet welded joints used SUS304A austenitic stainless steel, especially fatigue strength of corroded welded joint by salty environment.The main results of fatigue tests were as follows:(1)The 2x106 fatigue strength of load-carrying type fillet welded joints were 64MPa for non-corroded specimens and 61MPa for corroded ones respectively, however over 100MPa stress ranges, fatigue strength of the latter were lower than those of the former. (2) The 2x106 fatigue strength of non load-carrying type fillet welded joints were 101MPa for non-corroded specimens and 67MPa for corroded ones respectively. (3) The deterioration of fatigue strength of corrode specimens were caused by stress corrosion cracks which occurred in the heat-affected-zone by salty environment and residual stress of welding.

Microbial community of salt crystals processed from Mediterranean seawater based on 16S rRNA analysis

Phylogenetic analysis of 16S rRNA was used to investigate for the first time the structure of the microbial community that inhabits salt crystals retrieved from the bottom of a solar saltern, located in the coastal area of the Mediterranean Sea (Sfax, Tunisia). This community lives in an extremely salty environment of 250-310 g/L total dissolved salt. A total of 78 bacterial 16S rRNA clone sequences making up to 21 operational taxonomic units (OTUs), determined by the DOTUR program to 97% sequence similarity, was analyzed. These OTUs were affiliated to Bacteroidetes (71.4% of OTUs), and gamma-Proteobacteria and alpha-Proteobacteria (equally represented by 14.2% of the OTUs observed). The archaeal community composition appeared more diverse with 68 clones, resulting in 44 OTUs, all affiliated with the Euryarchaeota phylum. Of the bacterial and archaeal clones showing <97% 16S rRNA sequence identity with sequences in public databases, 47.6% and 84.1% respectively were novel clones. Both rarefaction curves and diversity measurements (Simpson, Shannon-Weaver, Chao) showed a more diverse archaeal than bacterial community at the Tunisian solar saltern pond. The analysis of an increasing clone's number may reveal additional local diversity.

Surviving Salt: How Do Extremophiles Do It?

​ImmersedImmersed in waters saltier than chicken soup, salt-tolerant “halophilic” microorganisms are able to thrive in conditions that would reduce a less-adapted organism to a shriveled remnant. One way halophilic archaea avoid this fate is by bathing their molecular machinery in a similarly salty intracellular environment that would cause ordinary proteins to lose their shape. How do the proteins inside these cells survive?

Stability of liquid saline water on present day Mars

Perchlorate salts (mostly magnesium and sodium perchlorate) have been detected on Mars' arctic soil by the Phoenix lander, furthermore chloride salts have been found on the Meridiani and Gusev sites and on widespread deposits on the southern Martian hemisphere. The presence of these salts on the surface is not only relevant because of their ability to lower the freezing point of water, but also because they can absorb water vapor and form a liquid solution (deliquesce). We show experimentally that small amounts of sodium perchlorate (∼ 1 mg), at Mars atmospheric conditions, spontaneously absorb moisture and melt into a liquid solution growing into ∼ 1 mm liquid spheroids at temperatures as low as 225 K. Also mixtures of water ice and sodium perchlorate melt into a liquid at this temperature. Our results indicate that salty environments make liquid water to be locally and sporadically stable on present day Mars.

Mangroves Living at the Edges: A Social Survey Based on Environmental Issue

Mangroves form a unique ecosystem in a coastal environment that is in constant flux and forms productive biomes. They thrive in a salty environment like coastal regions and estuaries and aid towards disaster management by facing the onslaught of giant waves such as Tsunami. It is an important asset from an ecological standpoint. In recent years, Mangrove communities have been uprooted and destroyed due to anthropogenic activity. Realizing the importance of mangroves, a community based awareness survey was made and the importance of mangroves and its possible role in disaster mitigation are emphasized. Survey reveals joint efforts should be taken by both the government and the local community to conserve and grow mangroves to save mankind from disaster.

ENHANCEMENT OF SHG IN FUSED SiO2 BY CORONA POLING UNDER WATER, WATER VAPOR AND SALTY ENVIRONMENTS

We found that optical nonlinearity in SiO2 glass sample can be greatly enhanced when sample is poled in wet and salty environments, and the nonlinearity in the sample can be reduced drastically when sample is washed in water. Possible causes for the observed enhancement and reduction of optical nonlinearity in SiO2 glass are discussed.

Production of an extracellular thermohalophilic lipase from a moderately halophilic bacterium, Salinivibrio sp. strain SA‐2

Fifty strains of moderately halophilic bacteria were isolated from various salty environments in Iran. A strain designated as SA-2 was shown to be the best producer of extracellular lipase and was selected for further studies. Biochemical and physiological characterization along with 16S rDNA sequence analysis placed SA-2 in the genus Salinivibrio. The optimum salt, pH, temperature and aeration for enzyme production were 0.1 M KCl, pH 8, 35 degrees C and 150 rpm, respectively. The enzyme production was synchronized bacterial growth and reached a maximum level during the early-stationary phase in the basal medium containing 1 M NaCl. Triacylglycerols enhanced lipase production, while carbohydrates had inhibitory effects on it. The maximum lipase activity was obtained at pH 7.5, 50 degrees C and CaCl(2) concentration of 0.01 M. The enzyme was stable at pH range of 7.5-8 and retained 90% of its activity at 80 degrees C for 30 min. Different concentrations of NaNO(3), Na(2)SO(4), KCl and NaCl had no affect on lipase stability for 3 h. These results suggest that the lipase secreted by Salinivibrio sp. strain SA-2 is industrially important from the perspective of its tolerance to a broad temperature range, its moderate thermoactivity and its high tolerance to a wide range of salt concentrations (0-3 M NaCl).

Simulation of charge reversal in salty environments: Giant overcharging?

We have performed MD simulations of a highly charged colloid in a solution of 3:1 and additional 1:1 salt. The dependency of the colloid's inverted charge on the concentration of the additional 1:1 salt has been studied. Most theories predict, that the inverted charge increases when the concentration of monovalent salt grows, up to what is called giant overcharging, while experiments and simulational studies observe the opposite. Our simulations agree with the experimental findings and shed light onto the weaknesses of the theories.

The microbial case for Mars and its implication for human expeditions to Mars

Mars is considered as key target for the search of life beyond the Earth. As well as carbon based chemistry and an adequate energy source, water in liquid phase has been considered a prerequisite for habitability. By analogy with terrestrial extremophilic microbial communities, e.g., those thriving in arid, cold, salty environments and/or those exposed to intense UV radiation, potential oases on Mars are suggested. They are connected with areas where liquid water still exists under the current conditions, but also sulfur rich subsurface areas for chemoautotrophic communities, rocks for endolithic communities, permafrost regions, hydrothermal vents, soil or evaporite crusts are of interest. The presence of humans on the surface of Mars will substantially increase the research potential; however, prior to any human exploratory mission the critical issues concerning human health and wellbeing as well as planetary protection issues need to be investigated.

Salt Pretreatment Enhance Salt Tolerance in Zea mays L. Seedlings

Recent molecular studies show that genetic factors of salt tolerance in halophytes exist in glycophytes too, but they are not active. If these plants expose to low level salt stress these factors may become active and cause plants acclimation to higher salt stresses. So because of the importance of these findings in this research the effect of salt pretreatment has been examined in Zea mays seedlings. To do the experiment four day old Zea mays seedlings (Var. single cross 704) pretreated with 50 mM NaCl for the period of 20 h. Then they were transferred to 200 and 300 mM NaCl for 48 h. At the end of treatment roots and shoots of seedlings were harvested separately. The changes of K+ -leakage, the amount of malondialdehyde, proline, soluble sugars and the Hill reaction rate were analyzed. The results indicated that the amount of K+ -leakage and malondialdehyde (MDA) have been increased because of salt-induced lipid peroxidation and membrane unstability. Soluble sugars and proline as osmoregulators has been increased in stress condition and in pretreated plants with NaCl were the highest. The rate of Hill reaction was reduced significantly in stressed plants. Therefore we concluded that salt stress causes serious physiological and biochemical damages in plants and salt pretreatment enhances tolerance mechanisms of plants and help them to tolerate salt stress and grow on salty environments.

A traditional Japanese-style salt field is a niche for haloarchaeal strains that can survive in 0.5% salt solution

BackgroundMost of the haloarchaeal strains have been isolated from hypersaline environments such as solar evaporation ponds, salt lakes, or salt deposits, and they, with some exceptions, lyse or lose viability in very low-salt concentrations. There are no salty environments suitable for the growth of haloarchaea in Japan. Although Natrialba asiatica and Haloarcula japonica were isolated many years ago, the question, "Are haloarchaea really thriving in natural environments of Japan?" has remained unanswered.ResultsTen strains were isolated from a traditional Japanese-style salt field at Nie, Noto Peninsula, Japan by plating out the soil samples directly on agar plates containing 30% (w/v) salts and 0.5% yeast extract. They were most closely related to strains of three genera, Haladaptatus, Halococcus, and Halogeometricum. Survival rates in 3% and 0.5% SW (Salt Water, solutions containing salts in approximately the same proportions as found in seawater) solutions at 37°C differed considerably depending on the strains. Two strains belonging to Halogeometricum as well as the type strain Hgm. borinquense died and lysed immediately after suspension. Five strains that belonged to Halococcus and a strain that may be a member of Halogeometricum survived for 1–2 days in 0.5% SW solution. Two strains most closely related to Haladaptatus possessed extraordinary strong tolerance to low salt conditions. About 20 to 34% of the cells remained viable in 0.5% SW after 9 days incubation.ConclusionIn this study we have demonstrated that haloarchaea are really thriving in the soil of Japanese-style salt field. The haloarchaeal cells, particularly the fragile strains are suggested to survive in the micropores of smaller size silt fraction, one of the components of soil. The inside of the silt particles is filled with concentrated salt solution and kept intact even upon suspension in rainwater. Possible origins of the haloarchaea isolated in this study are discussed.

Aspectos físico-químicos e biológicos relacionados à ocorrência de Biomphalaria glabrata em focos litorâneos da esquistossomose em Pernambuco

This study analyzes the physico-chemical and biological parameters of freshwater aquatic environments in coastal areas of the State of Pernambuco, Brazil, where snail vector foci and cases of schistosomiasis have been recorded. The tests were carried out using standard methods and sediments were analyzed using the X-ray fluorescence technique. The micro-algae were analyzed using conventional microscopy. The most abundant chemical elements in the sediments were Fe, Ca, Si and Al and there were high concentrations of electrolytes in comparison with data published in the literature. The mean values for salinity (7.7 g/L) and sulfate (489 mg/L) were much higher than normal for freshwater environments. The micro-algae identified are those that inhabit environments with higher levels of salinity. The snail Biomphalaria glabrata seems, therefore, to be more tolerant to salty environments and this constitutes a risk of spread of schistosomiasis.