Increase In Oxygen Flux Research Articles

Interfacial adsorption of microorganisms and its effect on oxygen absorption by fermentation broths

Steady-state mass transfer experiments were done to determine whether certain strains of bacteria in homogeneous suspension will accumulate at the gas:liquid interface and thereby significantly increase the oxygen transfer rate to the suspension. In particular, with suspensions ofB. licheniformis, the measured transfer rates are as much as three times the rate expected for a uniform suspension. In contrast, suspensions ofM. luteus show no increase in oxygen flux above expected values. The fact thatB. licheniformis is motile, whereasM. luteus is not suggests that cell motility may play an important role in the accumulation process.

Mitochondrial function in the presence of myoglobin.

The effect of myoglobin on oxygen consumption and ATP production by isolated rat skeletal muscle mitochondria was studied under steady-state conditions of oxygen supply. A method is presented for the determination of steady-state oxygen consumption in the presence of oxygen-binding proteins. Oxygen consumed in suspensions of mitochondria was replenished continuously by transfer from a flowing gas phase. Liquid-phase oxygen pressure was measured with an oxygen electrode; the gas-phase oxygen concentration was held constant at a series of fixed values. Oxygen consumption was determined from the characteristic response time of the system and the difference in the steady-state gas- and liquid-phase oxygen concentrations. ATP production was determined from the generation of glucose 6-phosphate in the presence of hexokinase. During steady-state mitochondrial oxygen consumption, the oxygen pressure in the liquid phase is enhanced when myoglobin is present. Functional myoglobin present in the solution had no effect on the relation of mitochondrial respiration and ATP production to liquid-phase oxygen pressure. Myoglobin functions in this system to enhance the flux of oxygen into the myoglobin-containing phase. Myoglobin may function in a similar fashion in muscle by increasing oxygen flux into myocytes.

SOME OBSERVATIONS ON OXYGEN TRANSPORT IN CONIFER SEEDLINGS

SummaryThe diffusive flux of oxygen from the roots of intact conifer seedlings was measured by a polarographic technique. With an anaerobic solution bathing the roots maintained at 23° C and with their aerial parts in air, flux rates were appreciable from eight of the twenty‐five seedlings tested. When the aerial parts were placed in oxygen, there was a large increase in flux from each pine seedling. While their general response was barely measurable, a significant but much smaller increase occurred from eight of the spruce. Oxygen transport through the plants appeared to be by diffusion chiefly in the gas phase and significant flux rates from the roots with aerial parts in air might indicate some capacity for wet soil tolerance in the seedlings concerned.When the external concentration of oxygen was increased five‐fold there was a disproportionate increase in oxygen flux from pine roots indicating that respiration in the plants might be affecting the flux rates. By cooling the bathing medium to 30 C a further demonstration of the respiratory effect‐a large increase in flux rate‐was obtained. With respiration reduced by cooling, the flux rates from the pine seedlings increased approximately five‐fold for a five‐fold increase in the external oxygen concentration. Cooling did not induce any pronounced response from the spruce seedlings.Internal diffusional resistance and oxygen leakage from the sub‐apical parts of the roots may account for the absence of high apical flux rates in the pines and the extremely low readings recorded for the spruce seedlings.

Rhizosphere Oxidation in Rice: An Analysis of Intervarietal Differences in Oxygen Flux from the Roots

AbstractThe polarographic technique (Armstrong 1967) has been found suitable for the detection of significant intervarietal differences in oxygen diffusion from rice roots. All the evidence obtained supports the thesis that intervarietal differences in oxygen diffusion rate occur and the varieties tested may be arranged in order of increasing oxygen flux as follows N 36 < N 22 < N 29 < N 32 < Yubae. The lowest oxygen flux rates are found in those varieties (N 22 and N 36) susceptible to Akagare disease of rice while the flux rates of varieties resistant to Akagare (N 29 and N 32) are higher. On the basis of these results one would also expect Yubae to be resistant to Akagare.The results are discussed with reference to previous work which has shown the oxidising activity and carbohydrate exudation properties of rice roots to be similarly correlated with resistance or susceptibility to Akagare.Attention is drawn to what it is felt are the shortcomings in existing techniques for measuring the oxidising activity of roots.It is suggested that with certain provisions the polarographic technique may he found useful in any effort to build up high oxidising power into the new plant type proposed for the tropics.