Sequence of Pigment Formation in the Mycelia of Defective Strains Obtained from Penicillium islandicum Sopp. By UV-irradiation

Abstract

On the basis of the experiments on pigment formation in several strains obtained from Penicillium islandicum Sopp, by UV-irradiation, biosynthetic interrelationships of the pigment components may be summarized as follows: 1) The strains obtained by irradiation are not mutants caused by gene mutation, but defective strains due to cytoplasmic change in irradiated spores.
2) In the strain NRRL 1175, the pathway leading to skyrin, oxyskyrin and skyrinol is found to be quite stable against UV-irradiation, and the loss or recovery of individual pigments has been achieved step by step during successive culture. Therefore, these 3 pigments are involved in the main pathway which proceeds according to the following fashion: skyrin→oxyskyrin→skyrinol. However, chrysophanol, emodin and flavoskyrin are unstable, and the appearance or disappearance of these pigments takes place independently of each other.
The biosynthetic route of the pigments in the strain NRRL 1175 is shown in Fig. 2 in the text.
3) In some defective strains obtained from the strain NRRL 1036, a faint new pigment spot comes into appearance in place of spot-j on the chromatogram only after disappearance of the latter pigment. This new pigment was identified as skyrinol by paper chromatography (Table 5). Thus, it is likely that skyrinol is also present in the strain NRRL 1036 probably being masked by preponderant spot-j on the chromatogram. Therefore, the route, skyrin→ oxyskyrin→skyrinol, is the main pathway also in this strain.
Islandicin and iridoskyrin are formed from a common precursor in a competitive manner. The interrelationship between rubroskyrin and luteoskyrin is quite similar to that between islandicin and iridoskyrin.
In view of these experimental findings, a scheme of pigment synthesis in the strain NRRL 1036 is illustrated in Fig. 3 in the text.
4) Erythroskyrin stands outside the biosynthetic route of anthraquinones.
5) The most plausible feature of the biosynthesis of a group of anthraquinones in the two chemical strains of Penicillium islandicum Sopp. is mapped out in Fig. 4 in the text.