Mechanism of Photoregulated Carotenogenesis inRhodotorula minutaII. Aspects of Photoregulative Reaction

摘要

The photoregulation of carotenogenesis inRhodotorula minutawas found to consist of tow phases, a temperature-independent photochemical reaction (light process) and temperature-dependent but light-independent biochemical reactions (dark process). These processes were separately examined by regulating the temperature and were characterized as follows:1) The quantity of carotenoid produced [C(μg g−1)] and the rate of carotenoid production [Vc(μg g−1hr−1)] in the dark process were regulated by the light dose [D(erg cm−2)] to which cells were exposed in the light process. These relationships were expressed by the equations:C=9.1 logD−62.0 andVc=0.81 logD−5.60. This photoresponse followed the Roscoe-Bunsen reciprocity law.2) The induced state toward carotenogenesis, once acquired in the light process, was very stable, suggesting that the proposed photochemical product is stable as an inducer of carotenogenesis and decreases only in conjunction with carotenoid biosynthesis.3) The photochemical reaction was oxygen-independent, but subsequent dark reactions were completely dependent on oxygen.4) Postulated compounds related to the photochemical reaction were not metabo