Aspergillus niger

8.8.21

The Fungus

Aspergillus niger is one of Aspergillus’ four species known to cause invasive disease in humans (others being A fumigatus, A flavus and A terreus).

However, it is possibly the least common amongst the four. FDA classed it safe [GRAS] for industrial use.

In nature, it is found on soils, plants, food and spices.

Identification

It initially forms white colonies, which quickly becomes black, with a yellow back. Conidia is rough, brownish-black, biseriate, and cover the entire vesicle.

A key feature in diagnosing A. niger infection is the presence of calcium oxalate crystals on pathological examination. The presence of crystals can be taken as an indication of A niger infection.

Virulence factor

Toxin – malformin C, ochratoxin A

Infection

  • It is the commonest cause of otomycosis – colonise the ear canal, appearing as a black tuft.

  • Cutaneous infection [Loudon, 1996].

  • Pulmonary infection and invasive aspergillosis.

Treatment

Otomycosis

  • Cleaning and topical antifungals (clotrimazole, miconazole).

  • Severe infection may need oral antifungals.

  • Invasive diseases may need IV antifungal.

Invasive aspergillosis

  • Voriconazole or isavuconazole +/- Echinocandin

  • Amphotericin B preparations.

Non-medical use

  • Aspergillus niger has much non-medical use – production of citric acid, waste management, biotransformation.