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KMID : 0368419590020010001
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Journal of Plant Biology
1959 Volume.2 No. 1 p.1 ~ p.12
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SOME PHYSIOLOGICAL STUDIES ON THE UTILIZATION OF ORAGANIC SUBSTRATES BY EUGLENA GRACILIS VAR, BACILLA 10616 IN LIGHT AND IN DARKNESS
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Lee Min-Jai
Park Sang-Shin
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Abstract
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1) The comparative studies of the quantitative measurement of growth characteristics and utilization of substrates by Euglena gracilis var. bacilla 10616 in the light and in darkness have been carried out. Endogenous respiration, effect of respiratory inhibitors and responses to the added substrates for the exogenous respiration are also investigated.
2) All cultures are grown in the open air under the continuous illumination of fluorescent light of 3500 lux at room temperature, the growth rate of the culture in the basal medium added 0.5% lactate is found to be the highest.
The growth rate decreases successively for the cultures of 0.5% sucinate, 0.5% Na-acetate, 0.5% malate, and control. There is no growth in the basal medium added 0.5% butyrate and 0.5% hydroquinone. The similar results are obtained for the mentioned cultures in the darkness. However, the growth rate in basal medium added 0.5% g1ucose and 0.5% sucrose does seem to increase in the darkness unlike the illumination.
3) The endogenous rate of respiration for the organism cuitured photosynthetically is about 12.94u1 02/mg/hr, in basal medium and the respiratory quotient is about 0.84. The rate is decreased by starvations to 6.5ul 02/㎎/hr, about to a half, but the respiratory quotient does net change.
4) The oxygen consumption during initial 2 hours in suspending solution ranging from pH 4.5 to pH 9.3 is highest at pH 4.5 in which the algae had grown, at pH 5.5 and at pH 6.9.
5) Endogenous respiration of the cells is strongiy inhibited by 0.1 M of potassium cyanide, malomic acid, sodium fluoride and iodo-acetic acid. It is also strongly inhibited by 0.01 M of potassium cyanide.
6) The respiratory response to added substrates for the exogenous respiration in the organism is coincided with the rate in the basal medium added the substrate in 1ight and in darkness, whether the cells are fed or starved.
7) According to the results of this study, there seems to be the flexibility of the interconversion between photosynthesis and chemosynthesis, heterotropic mode of metabolism, in Euglena gracilis var. bacillaris, and that this organism utilizes the lactate most.
It also may be suggested that the enzyme systems linked in the each steps of Embden-Myerhof -Parnas path way and TCA cycle seem to exist in this organism.
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