✍ Scribed by Sch�n, G.
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The Function o/ Reserve-Material /or the Adaptive Utilization o/Fructose, and the Synthesis o/ Bacterio~hlorophyll in Anaerobic Dark and Light Cultures o/ Rhodospirillum rubrum Summary. Rhodospiriltum rubrum needs exogenous carbon and nitrogen sources in addition to reserve material for bacteriochlorophyll synthesis in anaerobic cultures in the dark. Under these conditions fructose is a good substrate for growth and synthesis of bacteriochlorophyll. The utilization of fructose is adaptive and quantitatively dependent on the amount of reserve materials. The rate of pigment synthesis is increased after a lag phase of several hours. An aerobic preincubation with fructose reduces the lag phase to about 50O/o . During the first 2--4 h the rate of bacteriochlorophyll synthesis is lower when the cells are provided with fructose than with malate. After this time the production of bacteriochlorophyll on fructose is accelerated, whereas the synthesis rate on malate remains constant.
Cells which have been preadapted on fructose aerobically in the dark are able to synthesize pigment in a following anaerobic dark culture even in the absence of reserve materials. However, the rate of synthesis is lower than in the presence of reserve materials. The drop of pH by fermentation products and the resulting decrease of synthesis rate are removed by the addition of CaCO a. The fermentation metabolism on fructose enables the cells not only to synthesize pigment but also to grow and to form thylakoids. Fructose also is a good substrate in photosynthetic cultures. However, the synthesis of bacteriochlorophyll at the beginning of the anaerobic light culture likewise is related to the presence of reserve materials and to the preculture conditions.
Ffir eine signifikante B.-Chlorophyllbildung anaerob im Dunkeln ist bei Rhodospirillum rubrum neben Reservestoffen in den Zellen ein exogenes Substrat und eine :N-Quellc notwendig (NHd+). Fructose kann in anaerober Dunkelkultur als Substrat fiir die B.-Chlorophyllbildung dienen. Die Verwertung ist aber adaptiv und stark vom Gehalt an Reservesubstanzen abh~ngig. Eine Steigerung der Pigmentsynthese tritt erst nach einer mehrstfindigen lag-Phase ein, die durch elne aerobe Vorbebriitung mit Fructose um etwa die H~tlfte verkfirzt werden kann. Die Syntheserate des B.-Chlorophylls ist in den ersten 2--4 Std mit Fructose geringer als mit Malat als Substrat, steigt dann abcr stark an, w~hrend mit Malat die Rate etwa konstant bleibt.
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## Eingegangen am 8. M~rz 1972 The Synthesis of Volatile Acids by Fermentation of Pyrnvate and Fructose in Anaerobic Dark Cultures of Rhodospirillum rubrum Summary. Under anaerobic conditions in the dark R. rubrum produced mainly acetate and propionate from exogenous and endogenous substrates. Wi