Pigment production by Cryptococcus neoformans from para- and ortho-Diphenols: effect of the nitrogen source

Abstract

Cryptococcus neoformans produced pigments when p-diphenols were substrates in a glucose-amino acid-salts medium. The best substrates were 2.5-dihydroxybenzoic acid and 2,5-dihydroxybenzenesulfonic acid. In contrast to the cellular pigment production from o-diphenols (hydroxyl groups in the 2,3or 3,4-position of phenyl ring), the p-diphenols (1,4or 2,5-positions for the hydroxyl groups) produced large amounts of soluble pigments that diffused into the medium. When an optimal source of nitrogen (glutamine, glycine, and asparagine) was used, 89% of the C. neoformans strains produced pigments from p-diphenols. In contrast, 0 to 67% of the strains produced pigments when a suboptimal nitrogen source (proline, ammonium sulfate, ornithine, and methionine) was used. When glutamine-glycine-asparagine was the nitrogen source, 100% of the C. neoformans strains produced pigments from o-diphenols, whereas 77 to 100% of the strains produced pigment when proline-ammonium sulfateornithine-methionine was the nitrogen source. Cryptococcus species other than C. neoformans and all tested Candida species failed to produce pigments from any of the substrates except when hydroquinone was used. A combination of glutamine-glycine-asparagine and 3,4-dihydroxyphenylalanine allowed differentiation of colonies of C. neoformans from C. albicans in 3 to 6 days. These data showed that pigment production from o-and p-diphenols served as an excellent biochemical test for the identification of C. neoformans. MATERIALS AND METHODS Yeast cultures. Thirty strains of Cryptococcus species including C. neoformans (nine strains), C. luteolus (two strains), C. terreus (five strains), C. albidus (five strains), C. diffluens (three strains), and C. laurentii (six strains) were used in the study. The Cryptococcus cultures were supplied by William Kap

Role of laccase in the biology and virulence of

“…Laccase of C. neoformans was initially referred to as a phenol oxidase or diphenol oxidase because of its ability to make colored products from a wide variety of phenolic compounds having two hydroxyl groups, but not tyrosine [17]. However, a number of enzymes including tyrosinases, peroxidases and the yeast iron transporter, Fet3, also share these substrate activities, thus requiring additional studies to identify the enzyme as a laccase [10].…”

Isolation of Cryptococcus neoformans in Antwerp Zoo's nocturnal house

“…The yeast produces laccase, a phenoloxidase enzyme forming a melanin-like pigment when growing on a substrate containing polyphenolic compounds such as wood pulp lignin. 27,28 High number of Cr. neoformans colonies were isolated from tree-trunks and -stumps in the enclosures of the nocturnal animals in Antwerp Zoo.…”

The structural unit of melanin in the cell wall of the fungal pathogenCryptococcus neoformans

“…C. neoformans is a unique system for the study of melanin biology because unlike other melanotic fungi, only exogenously provided catecholamines or diphenolic substrates, such as dihydroxyphenylalanine (L-DOPA), are utilized for melanin synthesis and not as an energy source (11)(12)(13). Consequently, it is possible to selectively label the melanin polymer with NMRor radioactive isotopes, a property that has been exploited for melanin structural studies (14)(15)(16)(17)(18)(19).…”