Aspergillus species

A. oryzae (Ahlburg) Cohn. synonym A. flavus var oryzae

Colony characteristics. Colonies (CzA) growing rapidly, pale greenish-yellow, olive-yellow or with different shades of green, typically with dull brown shades with age.

Colonies on Czapek agar at 25°C attaining a diameter of 4-5 cm within 7 days, consisting of a felt of long conidiophores often intermixed with aerial mycelium. Conidial heads radiate, pale greenish yellow, later becoming light to dull brown. Conidiophores hyaline, up to 4-5 mm in length, mostly rough-walled. Vesicles subglobose, 40-80 µm in diam. Phialides often directly borne on the vesicle or on metulae, usually measuring 10-15 x 3-5 µm. Metulae 8-12 x 4-5 µm. Conidia ellipsoidal when young, globose to subglobose when mature, 4.5-8 µm in diam, green, smooth to finely rough-walled.

Colonies on MEA growing faster though somewhat thinner. Poor growth on CREA, cream coloured reverse on AFPA.

Microscopy. Conidial heads radiate to loosely columnar, 150-300 micrometre diam. Conidiophore stipes hyaline, up to 4-5 mm in length. Vesicles subspherical, up to 75 micrometre diam. Conidiogenous cells uniseriate and biseriate. Metulae or phialides covering the entire surface or the upper three-fourths of the vesicle. Conidia (sub) spherical to ovoidal, 4.5-8(-10) x 4.5-7 micrometre, smooth walled to roughened, greenish to brownish.

Pathogenicity. This species was reported as responsible of invasion of paranasal sinuses (Green et al., 1969; Byard et al., 1986) and was implicated in cases of meningitis (Gordon et al., 1976), cerebritis (Ziskind et al., 1958), pulmonary infections (Retamal et al., 1984; Wan-Qing, 1988), otomycosis (Rippon, 1982; Rinaldi, 1983) and scleritis (Stenson et al., 1982). There is one report of involvement in a kidney infection in an albatross (Tham et al., 1974).

Notes. This species has been predominantly isolated from soils, vegetative plant parts, seeds, and cotton fabrics. It is also used in food fermentations, in the production of saki, shoyu, miso, and soy sauce, and as a source of industrial enzymes (some useful reviews are Pandey et al., 1999; O'Toole, 1997).
The occurrence of A. oryzae is mostly restricted to fermented food products or industrial environments. Therefore it is normally not expected in food samples of the indoor environment.

References -

Selected historical references are listed below

Gordon, M.A., Holzman, R.S., Senter, H., Lapa, E.W. & Kupersmith, M.J., (1976). Aspergillus oryzae meningitis. JAMA 235: 2122-2123.

Klich, M.A. & Pitt, J.I., (1988). A laboratory guide to the common Aspergillus species and their telomorphs. CSIRO, North Ryde, Australia, 116 pp.

O'Toole, D.K. (1997). The role of microorganisms in soy sauce production. Advances in Applied Microbiology 45: 87-152.

Pandey, A., Benjamin, S., Soccol, C.R., Nigam, P., Krieger, N. & Soccol, V.T., (1999). The realm of microbial lipases in biotechnology. Biotechnology and Applied Biochemistry 29: 119-131.

Raper, K.B. & Fennell, D.I. (1965).The genus  Aspergillus. Williams & Wilkins, Baltimore, 686 pp.

Retamal, C., Diaz, C., Salamanca, L., Ferrada, L. & Alvarez, de Oro, R., (1984). Aspergilosis pulmonar en Chile. Enfoque inmunologico. Bol. Micol. 2: 11-16.

Rinaldi, M.G., (1983). Invasive aspergillosis. Reviews of Infectious Diseases 5: 1061-1077.

Rippon, J.W., (1982). In: Medical Mycology. The Pathogenic Fungi and the Pathogenic Actinomycetes, 2nd Edn, W.B. Saunders Company, Philadelphia, USA, pp. 565-594.

Samson, R.A., Hoekstra, E.S. & Frisvad, J.C. 2004, Introduction to food- and airborne fungi: 80

Stenson, J., Brookner, A. & Rosenthal, S., (1982). Bilateral endogenous necrotising scleritis due to Aspergillus oryzae. Ann. Ophthalmol. 14: 67-72.

Tham, V.L., Purcell, D.A. & Schultz, D.J., (1974). Fungal nephritis in a grey-headed albatross. Jornal of Wildlife Diseases 10: 306-309.

Wan-Qing, L., (1988). Mycological identification of pulmonary aspergilloma caused by Aspergillus oryzae with proliferating heads. Rev. Iber. Micol. 5, Suppl. 1: 51.

Ziskind, J., Pizzolato, P. & Buff, E., (1958). Aspergilloma of the brain: report of a case. Am. J. Clin. Pathol. 29: 554-559.