The outer membrane protein (omp40) component from the chemolithoautotrophic acidophilic Thiobacillus ferrooxidans is apparently regulated by the external pH and the concentration of phosphorus. Its amino-terminal sequence showed little identity with the Escherichia coli OmpC, OmpF or PhoE porins, but was 38.5% identical to the outer membrane channel-forming protein NosA from Pseudomonas stutzeri, whose expression is also regulated environmentally. In addition, the partial amino acid sequence of T. ferrooxidans omp40 showed between 34 and 38% identity with the amino-terminal end of the small outer membrane proteins Rck and PagC from Salmonella typhimurium and OmpX from Enterobacter cloacae. 相似文献
Abstract The amounts of mRNA and protein of plasma membrane proton-ATPase were measured in the salt-tolerant yeast Zygosaccharomyces rouxii by Northern and Western blot analyses. Although their amounts were independent of growth phase, their synthesis were induced when yeast cells were grown in the presence of NaCl or were subjected to NaCl shock. This finding was consistent with our previous result that plasma membrane proton-ATPase activity was elevated in Z. rouxii cells grown in medium containing high concentrations of NaCl. 相似文献
1. 1.|The thermohaemolysis of human erythrocytes in NaCl/sucrose isotonic media can be best accounted for in terms of the colloid-osmotic theory of haemolysis.
2. 2.|The thermohaemolysis in NaCl saline was preceded by leakage of K+ and cell swelling. If the inner oncotic osmoactivity was balanced with external sucrose the cells progressively shrinked losing K+, but the haemolysis was strongly reduced.
3. 3.|Time dependence of the shrinking of cells and one-step resealed ghosts suspended in isotonic 60 mOsm NaCl/sucrose media was studied between 50 and 58°C.
4. 4.|After a lag period for cells only, this shrinking proceeded with apparently constant rate for cells and ghosts.
5. 5.|The rate constant of shrinking for cells and ghosts obeys the Arrhenius relation, giving the value of 250 ± 15 kJ/mol for the activation energy of shrinking in both cases. This is also the case for the activation energy of the membrane ion permeability constant.
6. 6.|These results are consistent with the thermal inactivation of membrane associated protein(s) acting as a trigger for the ion permeability barrier disturbance.
7. 7.|The mid-point temperature for these membrane events was about 61°C.
Author Keywords: Thermohaemolysis; membrane ion permeability; protein inactivation; colloid-osmotic lysis 相似文献
In this study, a multi-stage membrane process, assisted by vacuum evaporation and crystallization, for recovery of bio-based alpha-ketoglutaric acid from the actual post-fermentation broth was designed and investigated. In the first part of this study, pre-treatment of crude fermentation broth (centrifugation-ultrafiltration-nanofiltration) was carried out to remove biomass, proteins, sugars, part of inorganic ions and color compounds. The commercial ceramic UF membrane (15 kDa) and nanofiltration ceramic membrane (200 Da or 450 Da) were applied. Electrodialysis with a bipolar membrane was proposed for separation of ionic compounds and simultaneous electro-acidification to the acid form. During bipolar membrane electrodialysis carried out under acidic conditions, it was possible to remove close to 90 % of alpha-ketoglutaric acid. Moreover, the migration of other acids present in the fermentation broth (lactic and acetic) was significantly limited. The calculated specific energy consumption was low and equal to 0.6 kW h/kg. The final purification using crystallization assisted vacuum evaporation allowed obtaining alpha-ketoglutaric acid in solid form. Analysis of the final product showed that the proposed method of alpha-ketoglutaric acid recovery gives the acid of high purity equal to 94.8 %. Furthermore, the presented results have practical relevance and may in future be the basis for the development of separation technologies of alpha-ketoglutaric acid from the fermentation broth on industrial scale. 相似文献
In this paper, the ecological integrity hierarchy framework (EIHF) and the natural capital index framework (NCI) are integrated as decision-making tools for evaluating the natural capital of Mexico. Two hierarchy-levels of ecological integrity indicators are used to estimate the quality and quantity of the natural capital, the amount of ecological degradation and ecological sustainability. After human transformation, the extent still considered as “natural” in the country is ∼67%; while the amount of human transformed areas is ∼33%, which gives a total estimate of NCI = 0.334; i.e., only ∼33.4% of the national capital remains available, while ∼33% is ecologically degraded. Furthermore, the critical natural capital; i.e., the legacy for future generations that remains in the country is only ∼12%. The total estimated value of the current natural capital in Mexico is ∼$457.1 billion/yr, which is ∼435 times greater than the national GDP ($1.051 billion in 2010). The cost of maintaining the degradation of the natural capital is ∼$144.6 billion/yr (∼138 times greater than national GDP in 2010). The potential value of the natural capital after restoration would be ∼$602 billion/yr. Valuing the natural capital can be helpful for strategic environmental evaluations and useful for spatial decision support systems that evaluate natural capital as a decision-making tool. 相似文献