Alternaria alternata


Alternaria alternata (Fr.) Keissler

Clathrospora diplospora (Ellis & Everth.) Wehm.
Clathrospora elynae Rabenh.
Leptosphaeria heterospora (de Not.) Niessl

Alternaria tenuis Nees
Torula alternata Fr.


 A. Alternata is a cosmopolitan ubiquitous fungus. It grows in a wide range of habitats from dry arid regions of desert dunes to saline lakes.

This species has been isolated from various substrates and habitats such as:
  • audiovisual (magnetic tapes, negatives on non-varnished photographic plates)
  • waterlogged wood          
  • rubber
  • sand dunes
  • hydrocarbons
  • synthetic materials
  • paper
  • parchment
  • paint (synthetic and natural)
  • easel painting
  • murals and frescoes
  • plants
  • food products (fruits, vegetables, cereals, nuts …)
  • soil (cultivated, forests, rhizosphere of many plantations)
  • stextile (jute, cotton, wool)
A. Alternata feeds mites such as Acarus gracilis, A. siro, Tarsonemus waitei, and Acotyledon redikorzevi.
A. Alternata is toxic and pathogenic. The conidiophores are allergen and can cause serious allergic respiratory diseases (asthma, chronic sinusitis, and rhinitis). It can also cause cutaneous mycoses of the skin and of the scalp. Its mycotoxins are responsible for leukopenia.
It is also a phytopathogenic commonly found on tomatoes.
In vitro tests show that A. Alternata is susceptible to amphotericin B, fluconazole, itraconazole and ketoconazole.

Description and growth

On Malt-Agar growth medium (MA) (pH 6.5) – Relatively fast growing species. Brown-grey to black in colour, short and suede-like colonies with a white periphery. The reverse is dark brown to black in colour. In Vitro, some isolates remain sterile. The aerial growth is almost entirely composed of spore chains. The black conidiophores are 1-3 septate and smooth-walled, straight or flexuous with a sympodial growth. Their average size is 50 x 5µm. The conidia are produced through one or several pores in the conidiophore wall in simple or branched chains. These 60 x 15 µm multicellular conidia are brown to yellow-brown, club-shaped with an apical beak. The medium is slightly acidified (final pH 5).

recto - 26°C

verso - 26°C

On Czapek growth medium (initial pH 5.5, final pH 6)

recto - 26°C

verso - 26°C

On CYA growth medium (pH5.5) – very fast growing colonies reaching their maximum growth after a 6-day incubation period. Suede-like colonies with a mycelium network of a dense grey-brown colour and a brown-black reverse. The species basidified the medium (final pH 7).

recto - 26°C

verso - 26°C

recto - 37°C

verso - 37°C

Development on different materials.

A. Alternata on linen / on cotton linters / on acidic paper / on parchment / on leather (flesh)

Alternaria Alternata sur toile de lin

Alternaria Alternata sur linters de coton

Alternaria Alternata sur papier acide

Alternaria Alternata sur parchemin

Alternaria Alternata sur cuir (chair)


Aw 0.85-0.88

A. Alternata is saphrophytic and facultative tonophile (requires average humidity conditions).
Optimum growth at 25°C and pH4-5.4, but this fungus can grow in quite a wide range of pH from 2.7 to 8.
A. Alternata is able to develop in anoxic conditions (0.25% oxygen level).
Spores contain 86% of water and are viable for several years under very dry conditions.


A. Alternata is cellulolytic.

It uses the following elements as carbon sources:

  • D-galactose
  • maltose
  • raffinose
  • saccharose
And the following ones as nitrogen sources:
  • acetamine
  • acetate et ammonium oxalate
  • L-aspartic acid
  • L-glutamic acid
  • Ca(NO3)2
  • D- alanine
  • Glycine
  • L- phenylalanine
  • L-asparagine
  • Mg(NO3)2
  • ammonium nitrate and tartrate
  • peptone
  • urea
Synthesized compounds:
  • tenuazonic acid
  • 2 altenuenes
  • alternatiols
  • alternatoxins
  • amylases
  • 2 proteases 
The chemical analysis of the mycelium reveals the presence of:
  •  mannitol
  • a variety of fatty acids such as myristic acid, palmitic acid, stearic acid, oleic acid and linoleic acid.
  • 11 free amino acids
  • 14 linked proteins
The strain is able to tolerate 0.1% calcium cyanamide and to resist ultraviolet and radiations.


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