Effect of oxygen and light on the accumulation of bacteriochlorophyll in the rhizobial strain BTAi 1 [i. e. rhizosphere bacteria]
1995
Wettlaufer, S.H. (Boyce Thompson Inst. for Plant Research, New York (USA)) | Hardy, R.W.F.
Strain BTAi 1 is a facultative aerobe and produces maximum amounts of bacteriochlorophyll (BChl) at atmospheric oxygen concentrations. Levels of BChl are reduced by either lowering or raising the ambient oxygen concentration. BTAi 1 requires a photoperiod for maximal accumulation of BChl. The fluence that produces this maximal accumulation is approximately 35 mumols (-1) m(-2), BChl content is reduced by either lowering or raising the fluence from the above concentration. Accumulation of BChl occurs predominantly in the dark, provided that there has been exposure to a threshold level of light. After an initial light treatment, BChl accumulation is detectable after thirty minutes in the dark and continues to increase over the next twenty four hours. While BChl accumulation is light-stimulated, it is also light-inhibited during successive light-dark exposures. In addition, no BChl accumulates in the light after an initial continuous dark treatment, and a prolonged continuous light treatment produces reduced levels of BChl during the dark period. The inhibition by light is the same under ambient or subambient oxygen concentrations, suggesting that the cause of the inhibition is not simply photodegradation in the presence of oxygen and light
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