Photoinduced Carotenoid Synthesis Research Articles

Photoinduced carotenoid synthesis in perithecial-wall tissue of Neurospora crassa.

Photoinduced carotenoid synthesis in perithecial-wall tissue of Neurospora crassa.

Effect of light on nonphotosynthetic microorganisms. VI. Photochromogenicity in genera Micromonospora, Microbispora and Actinoplanes.

The effect of light on the pigmentation of various strains of Micromonospora, Microbispora and Actinoplanes was investigated. It was found that four of eight strains of Micromonospora, two of five strains of Microbispora and two of three strains of Actinoplanes were photochromogenic. These photochromogenic strains produced carotenoids by photoinduction. Biochemical studies on the mechanism of photochromogenicity in Micromonospora echinospora, Microbispora chromogenes and Actinoplanes philippinensis showed that photoinduced carotenoid synthesis in these strains consists of an initial temperature-independent photochemical reaction step and a series of dark metabolic reaction steps, which involve de novo protein synthesis.

Dark Conversion of Protochlorophyllide to Chlorophyllide following Brief Illumination and Temperature Dependence of Photo-Induced Carotenoid Synthesis in Rice (Oryza sativa L.) Seedlings

Summary Conversion of protochlorophyllide to chlorophyllide occurred both in light and darkness in rice (Oryza sativa L.) seedlings.The optimum temperatures for dark conversion during 1 and 2 h incubation were 37 and 27°C, respectively.The amount of carotene which subsequently accumulated in the dark was improved by light pretreatment, whereas xanthophyll levels were less dependent on pre illumination.Both carotene and xanthophyll formation was strongly dependent on the temperature during dark incubation and low temperatures were increasingly effective.

Mechanism of photoinduced carotenoid synthesis: Further studies on the action spectrum and other aspects of carotenogenesis

In order to identify the photoreceptor, an accurate action spectrum for photoinduced carotenoid synthesis in Mycobacterium sp. has been determined. This action spectrum shows maxima at 280–285, 365–370, 410–415, 443–448, and 465–470 nm. The energy needed to give half the maximum response at 445 nm was 5.3 × 10 4 ergs per square centimeter. This action spectrum suggests that either a flavin (or a flavoprotein) or a carotenoid-protein complex is the photoreceptor. Fractionation of the Mycobacterium sp. cells has resulted in a flavin-like fraction whose absorption spectrum is similar to the action spectrum. The absorption spectrum of carotenoids isolated from the dark-grown cells, on the other hand, is not similar to the action spectrum. In contrast to Mycobacterium sp., Mycobacterium marinum has an action spectrum which is suggestive of porphyrins. A porphyrin, tentatively identified either as mesoporphyrin or coproporphyrin, has been isolated from the M. marinum cells. It is possible that this porphyrin may function as the photoreceptor in this organism. Antimycin A and substituted mercuribenzoate ( p-hydroxymercuribenzoate and p-chloromercuribenzoate), known to mimic light in M. marinum and Fusarium aquaeductuum, respectively, were not effective in inducing carotenogenesis in Mycobacterium sp.

Absolute requirement for oxygen during illumination for photoinduced carotenoid synthesis

Absolute requirement for oxygen during illumination for photoinduced carotenoid synthesis

On the mechanism of photoinduced carotenoid synthesis: Aspects of the photoinductive reaction

Photoinduced carotenoid synthesis has been studied in two species of mycobacteria, Mycobacterium marinum and an unclassified species. The action spectra of photo-induction have been shown to be markedly different for these two organisms. The action spectrum for the Mycobacterium sp. has maxima at 365 and 460 mμ separated by a minimum at 395 mμ. The action spectrum of M. marinum has a principal maximum at 404 mμ and two lesser maxima at 493 and 577 mμ. It is likely that a flavin is the photoreceptor for the Mycobacterium sp. and a porphyrin for M. marinum. The photoinduction of carotenogenesis in Mycobacterium sp. was found to be depressed at acid pH while that of M. marinum was unaffected by that treatment. The photoinductive reaction of both organisms was inhibited by azide at acid pH.

ON THE MECHANISM OF PHOTOINDUCTION OF CAROTENOID SYNTHESIS.

1. The photoinduced carotenogenesis of a species of mycobacteria consists of a photoinductive reaction followed by certain metabolic reactions that result in greatly enhanced carotenoid synthesis. 2. The action spectrum of photoinduction was found to have maxima at 365 mμ and 460 mμ, separated by a minimum region at 395 mμ. 3. Evidence presented indicates the photoinductive reaction is a photooxidation. More than one quantum of light is required to induce each bacterium. 4. It is postulated that a compound capable of inducing a carotenogenic enzyme is formed in the bacteria as a result of exposure to light and oxygen. 5. During incubation following photoinduction there is a sequential appearance of the newly synthesized carotenoids. Phytoene and phytofluene are synthesized first, followed by the more highly unsaturated carotenoids. The oxygenated carotenoids are the last pigments to be synthesized. 6. Chloramphenicol is an effective inhibitor of this photoinduced carotenoid synthesis. Addition of chloramphenicol at various intervals of incubation after photo-induction results in a differential inhibition of the synthesis of the various carotenoids. This pattern of inhibition closely resembles the time sequence of appearance of these carotenoids.

Photoinduction of carotenoid synthesis of a mycobacterium sp.

The photoinduced carotenoid synthesis of a Mycobacterium sp. has been studied and found to closely resemble the same phenomenon that has been reported to occur in Neurospora crassa. It has been possible to divide photoinduced carotenogenesis of this Mycobacterium sp. into three distinct phases. 1. 1. The photoinduction step which requires oxygen and light (the blue portion of the visible spectrum). This phase is temperature independent and the only one for which light is necessary. 2. 2. The protein synthesis phase which lasts for the first 2 h of incubation following light stimulation. Chloramphenicol is an effective inhibitor of this phase. 3. 3. The final stage, carotenoid synthesis, is dependent upon the enzymes synthesized in the second step and begins after 1-1.5 h of incubation and lasts approx. 12 h.