Studies in carotenogenesis. 14. Carotenoid synthesis in the photosynthetic bacterium Rhodopseudomonas spheroides

Abstract

The presence of 2 major carotenoids-one yellow (Y) and one red (R) - together with 6 minor components in R. spheroides was confirmed. One of the minor fractions appears to be a mono-hydroxy derivative of Y. Y predominates in anaerobic and R in aerobic cultures. Y but not R disappears from aerobic cultures soon after they are fully grown. Synthesis of R and disappearance of Y when air is admitted to anaerobic cells resuspended in phosphate buffer was confirmed. Diphenylamine (1/70,000) inhibits growth and pigment synthesis for 5-6 days after which growth and carotenogenesis become normal. No saturated polyenes are synthesized on diphenylamine-containing media. Many compounds which inhibit growth of R. spheroides do not affect the yellow [forward arrow] red pigmentary change, a change which is very insensitive to inhibitors. Reasons for assuming that pigment Y may not be converted to pigment R in the yellow[forward arrow]red change are given.