In nature, light is one of most crucial environmental signals for developmental and physiological processes in various organisms, including filamentous fungi. We have found that both red light and blue light affect development in Monascus, influencing the processes of mycelium and spore formation, and the production of secondary metabolites such as gamma-aminobutyric acid, red pigments, monacolin K and citrinin. Additionally, we observed that the wavelength of light affects these developmental and physiological processes in different ways. These findings suggest that Monascus possesses a system for differential light response and regulation.

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The pigments produced by Monascus are a mixture that includes azaphilone pigments. We simultaneously analyzed the 11 identifi ed compounds present in Monascus pigments, and showed that there was a large variety of components produced by different strains and under different culture conditions. For example, pigments of Monascus pilosus NBRC4520 grown in potato dextrose broth were mainly composed of xanthomonascin A and monascorubrin. Ethanol extracts from cultured cells tended to contain more monascin and ankafl avin, and the nitrogen source also infl uenced the composition of pigment components produced. Moreover MK-1, a mutant of M. pilosus NBRC4520 that produces high levels of lovastatin and pigments (Miyake et al., 2006ab), was found to produce large amounts of rubropunctamine, monascorubramine, monascin and yellow II.Keywords: Monascus, pigments, composition *To whom correspondence should be addressed. E-mail: tsuyoshi_miyake@pref.okayama.lg.jp IntroductionThe pigments produced by Monascus are traditionally applied as natural coloring for foodstuffs, and recent studies have shown that some Monascus pigments have important biological functions such as anti-tumor activity. Components of Monascus pigments as a mixture, including several azaphilone and furanoisophthalide pigments, are roughly classified into red, purple and yellow compounds based on their optical spectra. In the past, the 11 compounds present in Monascus pigments have been identifi ed chemically. The identified red compounds are rubropunctatin (rR) and monascorubrin (rM), the purple compounds are rubropunctamine (pR) and monascorubramine (pM), and the yellow are monascin (yM), ankafl avin (yA), xanthomonascin A (yXa), xanthomonascin B (yXb), monascopyridine A (yMa), monascopyridine B (yMb), and yellow II (yY2) (Carvalho et al., 2003). Although the amount and quality of Monascus pigments are typically estimated by absorbance at 490/380 nm, it is known there are variations in the red appearance of commonly used pigments that have not been separated and characterized further. These variations may be largely dependent on the composition of pigment compounds, because the composition and total molecular amount of pigments can be different even if the absorbance at 490/380 nm is the same. Additionally, the synthesis of these compounds may be independently regulated by culture conditions.Monascus pigment compounds separated and purified from mixtures have been demonstrated to have antibiotic and/or cytotoxic activities. It was shown that rR, rM and amino acid derivatives of pigments have antibiotic activities (Martinkova et al., 1999;Kim et al., 2006), and yM and yA have anti-tumor and immunosuppressive activities (Su et al., 2005;Akihisa et al., 2005b). Hence, most of them might potentially have some chemopreventive effects (Akihisa et al., 2005a;Knecht and Humpf 2006).For the safe and successful application of Monascus pigments in the food and pharmaceutical industries, it is important to address the specific composition of pigments produced by Monasc...

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Mutants unable to grow on medium containing glutathione as a sole source of sulphur (GSH medium) were isolated from Saccharomyces cerevisiae strains carrying met17(deficiency of O‐acetylserine and O‐acetylhomoserine sulphydrylase). They were defective in the high‐affinity glutathione transport system, GSH‐P1. Newly acquired mutations belonged to the same complementation group, gsh11. However, it became apparent that gsh11 conferred the mutant phenotype not by itself but in collaboration with met17. Moreover, mutations conferring the defect in sulphate assimilation made the cell unable to grow on GSH medium in collaboration with gsh11. From this finding, we propose that the sulphate assimilation pathway acts as a sulphur‐recycling system and that this function is especially vital to the cell when the supply of glutathione is limited. Copyright © 1999 John Wiley & Sons, Ltd.