Penicillium psychrosexualis

Molecular phylogenetic analyses of the Penicillium fungus were performed using DNA sequences of the internal transcribed spacer region, partial β-tubulin and calmodulin genes. This information, in addition to analysis of excreted chemicals and macro- and microscopical characteristics, demonstrated that P. psychrosexualis belongs in the series Roqueforti (genus Penicillium, subgenus Penicillium sect. Roqueforti). This is grouping of related species with similar physiological characteristics that includes P. paneum, P. carneum, and P. roqueforti.^[1]

Penicillium psychrosexualis cultures are velvety, bearing woolly tufts in the center, and colored dull to dark green when grown on Czapek yeast agar. The odor of the fungus is similar to its close relative P. roqueforti. P. psychrosexualis produces cleistothecia (closed, spherical fruitbodies from which ascospores are released when its walls break or split) when grown between the relatively low temperatures of 9 and 15 °C (48 and 59 °F); no cleistothecia were observered when grown at 25 °C (77 °F). The cleistothecia are initially white, soft, and sterile, but after about three to four months become pale orange-brown, typically measuring 100–175 μm in diameter. Ascospores are ellipsoidal, and measure 4–5 by 3–4 μm.^[1]

The fungus produces several secondary metabolites: andrastin A, mycophenolic acid, patulin, and roquefortine C. A chemically uncharacterized compound isolated from the fungus has been given the tentative name "fumu". The metabolite profile of P. psychrosexualis is similar to that of P. carneum, but the latter species lacks "fumu" while producing cyclopaldic acid, isofumigaclavine A, and penitrem A.^[1]