排序方式: 共有8条查询结果,搜索用时 15 毫秒
1
1.
Goldberg E. Grace Raab Ted K. Desalles Paul Briggs Amy A. Dunbar Robert B. Millero Frank J. Woosley Ryan J. Young Hillary S. Micheli Fiorenza Mccauley Douglas J. 《Coral reefs (Online)》2019,38(2):347-357
Coral Reefs - Bolbometopon muricatum are ecologically unique mega-consumers in coral reef ecosystems. They primarily divide their dietary intake between living scleractinian corals and coral rock,... 相似文献
2.
The sulfur-containing amino acid, methionine, has a role in the physiological environment because of its strong interactions with metals. To understand these interactions of metals with methionine, one needs reliable dissociation constants for the protonated methionine species (NH(3)(+)CH(CH(2)CH(2)SCH(3))COOH; H(2)B(+)). The values of stoichiometric dissociation constants, pK(i)*, for protonated methionine species (H(2)B(+) if H(+)+HB, K(1); HB if H(+)+B(-), K(2)) were determined from potentiometric measurements in NaCl solutions as a function of ionic strength, 0.25-6.0 mol (kg H(2)O)(-1) and temperature (5-45 degrees C). The results were extrapolated to pure water using the Pitzer equations to estimate the activity of H(+), H(2)B(+), HB and B(-) as a function of ionic strength and temperature. The resulting thermodynamic values of K(1) and K(2) were fit to the equations (T/K): ln K(1)=69.0013-3496.58/(T/K)-10.9153 ln (T/K); ln K(2)=116.4162-10638.02/(T/K)-18.0553 ln (T/K) with standard errors of 0.003 and 0.033, respectively, for ln K(1)* and ln K(2)*. Pitzer interaction parameters (lambda(HB-Na) and zeta(HB-Na-Cl)) for the neutral HB were determined from literature data. The Pitzer parameters (beta(0)(H(2)BCl), beta(1)(H(2)BCl) and C(phi)(H(2)BCl)) for the interactions of H(2)B(+) with Cl(-) and Na(+) with and B(2-) (beta(0)(NaB), beta(1)(NaB) and C(phi)(NaB)) were also determined. These coefficients can be used to make reasonable estimates of the activity coefficients of methionine species and the pK(i)(*) for the dissociation of methionine in physiological solutions, composed mostly of NaCl over a wide range of temperature and ionic strength. 相似文献
3.
The effect of electrolyte concentration on attachment of Vibrio alginolyticus to hydroxyapatite was determined. Bacterial affinity for attachment to the surface and surface capacity were derived from linearization of bacterial adsorption isotherms. At low concentrations (<0.1 M) the affinity of the bacteria for the surface increased with increasing ionic strength, in agreement with the D.L.V.O. theory of colloid interaction. At higher concentrations, bacterial affinity for the surface decreased with increasing concentration of cations and was not related to ionic strength changes in the medium. These results demonstrate a change in the mechanism by which salts affect bacterial attachment at salt concentrations above 0.1 M. The results are consistent with the relationship between the proportion of attached bacteria and salinity observed in previously published field studies. The results may also resolve differences between various attachment studies carried out in different ionic strength media, utilizing different bacteria, surfaces, and experimental methods. 相似文献
4.
Effects of Inorganic Particles on Metabolism by a Periphytic Marine Bacterium 总被引:7,自引:6,他引:1
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Measurements were made of adsorption of a periphytic marine bacterium, glucose, and glutamic acid to inorganic particles in seawater and defined bacterial growth medium. Measurements of the metabolism of bacteria were made in the presence and absence of particles by microcalorimetry and radiorespirometry. It was found that hydroxyapatite adsorbs glutamic acid, but not glucose, from the experimental medium. It was also found that hydroxyapatite adsorbs essentially all of the bacteria from the medium when the bacterial concentration is approximately 6 × 105 bacteria per ml. If the bacterial concentration is approximately 6 × 107, then only a small fraction of cells become attached. It was therefore possible to select bacterial concentrations and organic nutrients so that bacterial attachment, organic nutrient adsorption, or both would occur in different experiments. In this experimental system the metabolism by attached and nonattached bacteria of adsorbing and nonadsorbing organic nutrients was measured. The results show that bacterial activity in this model system was not enhanced by the particles, regardless of whether the bacteria, the organic nutrient, or both were associated with the surface. In fact, the respiratory activity of the attached bacteria was diminished in comparison with that of free bacteria. 相似文献
5.
Microcalorimetric Measurements of Glucose Metabolism by Marine Bacterium Vibrio alginolyticus 总被引:3,自引:3,他引:0
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Microcalorimetric measurements of heat production from glucose by Vibrio alginolyticus were made to assess the viability of calorimetry as a technique for studying the metabolism of marine bacteria at organic nutrient concentrations found in marine waters. The results show that the metabolism of glucose by this bacterium can be measured by calorimetry at submicromolar concentrations. A linear correlation between glucose concentration and total heat production was observed over a concentration range of 8 mM to 0.35 μM. It is suggested that these data indicate a constant efficiency of metabolism for this bacterium over the wide range of glucose concentrations studied. 相似文献
6.
The kinetics of the formation of the purple complex [FeIII(EDTA)O2]3−, between FeIII-EDTA and hydrogen peroxide was studied as a function of pH (8.22-11.44) and temperature (10-40 °C) in aqueous solutions using a stopped-flow method. The reaction was first-order with respect to both reactants. The observed second-order rate constants decrease with an increase in pH and appear to be related to deprotonation of FeIII-EDTA ([Fe(EDTA)H2O]− ⇔ Fe(EDTA)OH]2− + H+). The rate law for the formation of the complex was found to be d[FeIIIEDTAO2]3−/dt=[(k4[H+]/([H+] + K1)][FeIII-EDTA][H2O2], where k4=8.15±0.05×104 M−1 s−1 and pK1=7.3. The steps involved in the formation of [Fe(EDTA)O2]3− are briefly discussed. 相似文献
7.
A negative correlation between adsorption of low molecular weight organic acids and sugars onto a hydroxyapatite surface and biodegradation rates of the compounds in the presence of the mineral was observed. Qualitatively, the effect was the same whether the organics were equilibrated with the surface prior to the addition of organisms or the organisms were preattached to the surface. Glucose, acetic acid, succinic acid, glutamic acid, and citric acid showed equilibrium adsorption values ranging from 0–94% from a 2M solution. Changes in both respiration and assimilation of the substrates in the presence of hydroxyapatite were inversely correlated with adsorption. 相似文献
8.
A method is described in which a flow sorption microcalorimeter was used to measure the heat production of Vibrio alginolyticus attached to polyacrylamide beads. Starved cells were attached to the beads and placed in the column of the calorimeter. Heat production from the metabolism of glucose by the attached cells was then determined. The specific rate of heat production of cells on the surface is compared with that of cells growing in solution. The results show a lowered rate of heat production per cell by the attached bacteria. 相似文献
1