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Influence of organic acids on intracellular pH 总被引:8,自引:0,他引:8
de Hemptinne A.; Marrannes R.; Vanheel B. 《American journal of physiology. Cell physiology》1983,245(3):C178
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Effects of oxygen, pH and nitrate concentration on denitrification by Pseudomonas species 总被引:2,自引:0,他引:2
Abstract The production of nitrogen-containing gases by denitrification in three organisms was examined using membrane inlet mass spectrometry. The effects of O2 (during both growth and maintenance) and of pH, nitrate concentration and carbon source were tested in non-proliferating cell suspensions. Two strains of Pseudomonas aeruginosa were capable of co-respiration of NO3 − and O2 and, under controlled O2 supply, gave oscillatory denitrification. Variations in culture and assay conditions affected both the rate of denitrification and the ratio of end products (N2 O:N2 ). Higher rates were seen following anaerobic growth. Optimum values of pH and nitrate concentration for denitrification are given. Generally, the optimum pH was 7.0–7.5, approximately that of the growth medium. Optimum nitrate concentration was generally 20 mM. 相似文献
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The influence of incubation temperature, and of acetic, lactic and citric acids on the minimum pH for the initiation of growth of six strains of Yersinia enterocolitica was determined. The strains included two of serotype O : 9, two of serotype O : 3, and one each of serotypes O : 8 and O : 5, 27. In a culture medium acidified with HCl to pH values between 4.0 and 6.0 at intervals of approximately 0.1 unit the minimum pH at which growth was detected after incubation at 20 degrees, 10 degrees, 7 degrees and 4 degrees C for 21 d was in the ranges 4.18-4.36, 4.26-4.50, 4.36-4.83 and 4.42-4.80, respectively. The minimum pH for growth was also determined in media that contained 17, 33 and 50 mmol/l acetic acid adjusted to pH values between 5.1 and 5.9 at intervals of approximately 0.2 unit, 24, 48 and 95 mmol/l citric acid adjusted to pH values between 4.1 and 4.9 at intervals of approximately 0.2 unit, and 22, 44, and 111 mmol/l lactic acid adjusted to pH values between 4.3 and 5.7 at intervals of approximately 0.4 or 0.5 unit. The effect of these concentrations of organic acids was, in most cases, to increase the minimum pH that allowed growth. The order of effectiveness of the organic acids in raising the minimum pH for growth was acetic greater than lactic greater than citric and the minimum inhibitory concentrations were greater at higher temperatures. 相似文献
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The influence of incubation temperature, and of acetic, lactic and citric acids on the minimum pH for the initiation of growth of six strains of Yersinia enterocolitica was determined. The strains included two of serotype O : 9, two of serotype O : 3, and one each of serotypes O : 8 and O : 5, 27. In a culture medium acidified with HC1 to pH values between 4.0 and 6.0 at intervals of approximately 0.1 unit the minimum pH at which growth was detected after incubation at 20°, 10°, 7° and 4°C for 21 d was in the ranges 4.18–4.36, 4.26–4.50, 4.36–4.83 and 4.42–4.80, respectively. The minimum pH for growth was also determined in media that contained 17, 33 and 50 mmol/1 acetic acid adjusted to pH values between 5.1 and 5.9 at intervals of approximately 0.2 unit, 24, 48 and 95 mmol/1 citric acid adjusted to pH values between 41 and 4.9 at intervals of approximately 0.2 unit, and 22, 44, and 111 mmol/1 lactic acid adjusted to pH values between 4.3 and 5.7 at intervals of approximately 0.4 or 0.5 unit. The effect of these concentrations of organic acids was, in most cases, to increase the minimum pH that allowed growth. The order of effectiveness of the organic acids in raising the minimum pH for growth was acetic > lactic > citric and the minimum inhibitory concentrations were greater at higher temperatures. 相似文献
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《Journal of Fermentation and Bioengineering》1994,77(5):562-564
The growth of alkalophilic Bacillus no. A-40-2 with nitrate as the nitrogen source was highly stimulated by the addition of 0.1% of certain amino acids, sugars, organic acids, nucleic acids, or Fe2+ or Mn2+ at concentrations of 10 mM or more to the medium, resulting in maximum growth after 24 h. Other alkalophilic Bacillus strains also showed the same results. A decrease in the amount of nitrate in the medium was observed. The optimum pH of nitrate reductase was 7.5. 相似文献
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Diel variations in carbon isotopic composition and concentration of organic acids and their impact on plant dark respiration in different species 下载免费PDF全文
M. M. Lehmann F. Wegener R. A. Werner C. Werner 《Plant biology (Stuttgart, Germany)》2016,18(5):776-784
Leaf respiration in the dark and its C isotopic composition (δ13CR) contain information about internal metabolic processes and respiratory substrates. δ13CR is known to be less negative compared to potential respiratory substrates, in particular shortly after darkening during light enhanced dark respiration (LEDR). This phenomenon might be driven by respiration of accumulated 13C‐enriched organic acids, however, studies simultaneously measuring δ13CR during LEDR and potential respiratory substrates are rare. We determined δ13CR and respiration rates (R) during LEDR, as well as δ13C and concentrations of potential respiratory substrates using compound‐specific isotope analyses. The measurements were conducted throughout the diel cycle in several plant species under different environmental conditions. δ13CR and R patterns during LEDR were strongly species‐specific and showed an initial peak, which was followed by a progressive decrease in both values. The species‐specific differences in δ13CR and R during LEDR may be partially explained by the isotopic composition of organic acids (e.g., oxalate, isocitrate, quinate, shikimate, malate), which were 13C‐enriched compared to other respiratory substrates (e.g., sugars and amino acids). However, the diel variations in both δ13C and concentrations of the organic acids were generally low. Thus, additional factors such as the heterogeneous isotope distribution in organic acids and the relative contribution of the organic acids to respiration are required to explain the strong 13C enrichment in leaf dark‐respired CO2. 相似文献
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The killing of Listeria monocytogenes following exposure to low pH, organic acids, and osmotic stress was enhanced by the addition of 5% (vol/vol) ethanol. At pH 3, for example, the presence of this agent stimulated killing by more than 3 log units in 40 min of exposure. The rate of cell death at pH 3.0 was dependent on the concentration of ethanol. Thus, while the presence 10% (vol/vol) ethanol at pH 3.0 stimulated killing by more than 3 log units in just 5 min, addition of 1.25% (vol/vol) ethanol resulted in less than 1 log unit of killing in 10 min. The ability of 5% (vol/vol) ethanol to stimulate killing at low pH and at elevated osmolarity was also dependent on the amplitude of the imposed stress, and an increase in the pH from 3.0 to 4.0 or a decrease in the sodium chloride concentration from 25 to 2.5% led to a marked reduction in the effectiveness of 5% (vol/vol) ethanol as an augmentative agent. Combinations of organic acids, low pH, and ethanol proved to be particularly effective bactericidal treatments; the most potent combination was pH 3.0, 50 mM formate, and 5 % (vol/vol) ethanol, which resulted in 5 log units of killing in just 4 min. Ethanol-enhanced killing correlated with damage to the bacterial cytoplasmic membrane. 相似文献
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Myosin filamentogenesis: effects of pH and ionic concentration 总被引:6,自引:0,他引:6
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Lipid solubility and the sourness of acids: implications for models of the acid taste receptor 总被引:2,自引:1,他引:1
Taste threshold concentrations (or equi-sour concentrations)of organic acids are significantly related to their octanol/waterpartition coefficients. Since the latter appear to model aqueous/membranepartitioning in biological systems this suggests that absorptionof an acid into the taste cell membrane plays an important rolein the perception of the sour taste.
*This work was performed whilst the author was Group R. &D. Chemist, Harp Lager Ltd., Manor Park, Alton, Hampshire, U.K. 相似文献
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Monomer nucleosomes (nu 1) from chicken erythrocyte nuclei were examined in aqueous buffers (8 greater than pH greater than 3) and in solvent mixtures (i.e., water and ethanol, ethylene glycol, dioxane, dimethyl sulfoxide, 2-methyl-2,4-pentanediol, polyethylene glycol, sucrose, or urea). Circular dichroism, laser Raman spectroscopy of nu 1, and the fluorescence of nu 1 labeled with N-(3-pyrene) maleimide on thiol groups of H3 histone were employed to detect conformational transitions in nu 1. The results of pH studies were as follows: 5.5 greater than pH greater than 4.8, suppression of DNA ellipticity and no change of histone alpha-helix; 4.6 greater than pH greater than 4.2 an irreversible increase in the B character of DNA, a slight loss of histone alpha-helix, and a parallel loss of pyrene excimer fluorescence; 4 greater than pH, aggregation of nu 1 and protonation of the DNA bases C and A. Results obtained in the studies of nu 1 in solvent mixtures included the following: sharp conformational transitions that variously involved an increase in the B character of DNA, a slight loss of histone alpha-helix, and a loss of pyrene excimer. Different solvents required different concentrations to effect these conformational changes. 相似文献
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The effects of pH, aluminium concentration and temperature on the embryonic development of the European common frog, Rana temporaria 总被引:1,自引:0,他引:1
The individual and combined effects of pH, aluminium concentration and temperature, on the development of common frog ( Rana temporaria ) embryos from an upland area of northern England, were investigated in a controlled laboratory study. There was strong evidence to suggest that embryonic survival was lower at pH 4.5 compared with pH 6.0. At pH 4.5, embryonic survival was reduced at the highest aluminium concentrations. There was no strong evidence for a reduction in embryonic survival at lower aluminium concentrations.
Gastrulation and hatching appeared to be the most sensitive stages to both pH and aluminium concentration.
There was strong evidence to suggest that temperature-shocked embryos had reduced survival when compared with those kept at a constant temperature, particularly at pH 4.5.
There was substantial variation in the survival of embryos from different clutches in the same pond with respect to low pH, aluminium concentration and temperatures. Thus R. temporaria has a wide genetic base from which to tolerate environmental changes. It is suggested, however, that the lethal and sublethal effects of low pH, high aluminium concentration and low temperature, could lead to a decrease in recruitment to the adult populations of R. temporaria in upland, northern England. 相似文献
Gastrulation and hatching appeared to be the most sensitive stages to both pH and aluminium concentration.
There was strong evidence to suggest that temperature-shocked embryos had reduced survival when compared with those kept at a constant temperature, particularly at pH 4.5.
There was substantial variation in the survival of embryos from different clutches in the same pond with respect to low pH, aluminium concentration and temperatures. Thus R. temporaria has a wide genetic base from which to tolerate environmental changes. It is suggested, however, that the lethal and sublethal effects of low pH, high aluminium concentration and low temperature, could lead to a decrease in recruitment to the adult populations of R. temporaria in upland, northern England. 相似文献
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Summary We examined the interactions of an abiotic factor (pH) and a biotic factor (density) on the survival and growth of two species of anuran larvae (Hyla gratiosa and Hyla femoralis) in outdoor tanks. Three levels of pH (4.3, 4.6, or 6.0) and three levels of density (0, 30 or 60 embryos) were arranged in a blocked design and replicated three times for Hyla gratiosa. At the end of this experiment the effects of pH (4.3, 4.6, or 6.0), density of H. femoralis (30 or 60), and prior use by H. gratiosa (at 0, 30, or 60 larvae per tank) on the survival and growth of H. femoralis, were examined. Higher density increased larval period and decreased size at metamorphosis of H. gratiosa. Lower pH decreased survival rate and also decreased size at metamorphosis. Body sodium concentrations were lowest at the low pH values. Lower pH increased the susceptibility of H. gratiosa tadpoles to the adverse effects of higher densities. For H. femoralis higher density decreased survival, increased larval period and decreased size at metamorphosis. Hyla femoralis also had lower survivorship at low pH and exhibited decreased size at metamorphosis. However, unlike the results with Hyla gratiosa, there were no interactive effects between pH and density for any of the life-history traits studied. The effect of previous colonization by H. gratiosa on H. femoralis survival was facilitative. Body sodium concentrations of H. femoralis were lowest at the highest pH value. Metamorphs of the same size had much lower levels of sodium in H. femoralis than H. gratiosa. In general, H. femoralis was less affected by pH variation than H. gratiosa. These results demonstrate that abiotic factors can interact strongly with biotic effects such as density and they suggest that interspecific interactions can be strongly modulated by the background abiotic environment. 相似文献
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Another explanation for the toxicity of fermentation acids at low pH: anion accumulation versus uncoupling 总被引:11,自引:0,他引:11
J.B. Russell 《Journal of applied microbiology》1992,73(5):363-370