Die Auswirkungen von Mangan-Mangel auf Wachstum und Photosynthese bei der BlaualgeAnacystis Nidulans

Summary

• 1. The strict photoautotrophic blue-green alga,Anacystis nidulans, has a high requirement for manganese; its absence from the culture medium causes significant changes in the morphology and the metabolism of the cells.

• 2. These effects though comparable with those described for green algae are more severe and irreversible. After 5 days of culture in manganese deficient medium cell division is increasingly inhibited while cell growth continues giving rise to filamentous giant cells.

• 3. Net synthesis of chlorophyll ceases after 5 days, that of carotenoids after 10 days; phycocyanin and RNA are synthesized at a small rate up to 15 days.

• 4. Photosynthesis of deficient cells (10 days old) as measured by their oxygen production at high light intensities is reduced to 60% of the rate of normal cells when based upon their chlorophyll content; based upon equal cell volume the rate of the deficient cells was only 28% of the normal ones.

• 5. After short-time photosynthesis with radioactive bicarbonate the¹⁴C-fixation in the petrolether, the alcohol-water and the insoluble fraction from deficient cells was significantly lower as compared with the corresponding fractions from normal cells.

• 6. The alcohol-water fraction from manganese deficient cells differs in the distribution pattern of the incorporated¹⁴C from that of normal cells insofar as aspartic acid has a higher, glutamic acid a lower content of¹⁴C. Moreover, no labelling of glycolic acid, malic acid and alanine occurs in deficient cells during these short-time incorporation experiments.

• 7. The results indicate that a correlation exists between high manganese requirement and strict photoautotrophy; inAnacystis the relation of manganese to photosynthesis is obviously not restricted to the mechanism of oxygen liberation but seems to exist on the reductive side of photosynthesis, too.