Saturday 14 June 2014
Cladosporium species (Revisitied)
Cladosporium species Revisited (Kind
Of) -A Black Mould -Hyphomycetes
This post is a bit of a revisitation to the fungus Cladosporium as I previously included
the genera in a previous post on Cladophialophoraspecies. You can compare the two more
thoroughly by checking out my previous post by clicking here.
Ecology: Cladosporium species
are cosmopolitan saprophytic fungi found in soil, on plant debris and leaf
surfaces.
Pathogenicity: Cladosporium
species are generally considered to be non-pathogenic although they may be
considered as possible opportunists in the severely debilitated host. Potentially pathogenic species previously
included under the Cladosporium
genera have recently been reassigned to the genera Cladophialophora (eg.
C.bantianum, C.carrionii). Cladosporium may be encountered in the
laboratory as a culture contaminant and must be distinguish from the pathogenic
Cladophialophora.
Macroscopic Morphology: The rate of growth is dependent on the
particular Cladosporium species and
can vary from slow to moderately rapid.
The isolate discussed in this post expanded in size rather slowly though
it matured to produce copious amounts of conidia rather quickly (~7 days). The colony was velvety to suede-like in
texture. Other sources describe Cladosporium’s texture as ranging from
powdery to woolly. The colony may become
slightly heaped and develop gentle folds as it ages. Colour ranges from greyish-green to
olivaceous-green to brownish-black. The
reverse is a dark brown to black in colour.
Cladosporium species on SAB, 15 Days at 30˚C (Nikon)
Cladosporium species on SAB, 25 Days at 30˚C (Nikon)
Microscopic Morphology: Cladosporium produces erect, dark,
septate hyphae. Conidiophores are also
darkly pigmented, may be septate and show tree-like branching. Fragile chains of dematiaceous blastoconidia
are produced and exhibit a dark hila or scar at their point of attachment to
the conidiophore or other conidia. The
1-4 celled conidia are round to oval (3 -6 µm X 4 - 12 µm) and may be
smooth-walled to verrucose in surface texture.
Cells on the conidiophore which bear the chains of conidia are sometimes
septate and appear in the shape of a ‘shield’.
These cells are also conidia but are referred to as shield cells. Chains of conidia easily disarticulate (break
up) and were frustratingly difficult to document using both adhesive tape andslide culture techniques.
Cladosporium species are not thermotollerant and some
species may not grow at 37˚C.
Cladosporium species produce darkly pigmented, septate, branching hyphae,
(LPCB, DMD-108, 400+10X)
Cladosporium species - Conidiophores are also darkly pigmented, may be septate and also show tree-like branching. (LPCB, DMD-108, 400+10X)
Cladosporium species - The Lactophenol cotton blue stain has taken more deeply in this preparation. Septate hyphae are clearly visible. (LPCB, DMD-108, 400X)
Cladosporium species -1-4 celled conidia are round to oval (3- 6 µm X 4-12 µm) and may be smooth-walled to verrucose in surface texture.
(LPCB, DMD-108, 1000X)
Cladosporium species -the structures are clearly evident here: septate hyphae, darkly pigmented conidiophores and oval conidia in chains.
(LPCB, DMD-108, 1000X)
Cladosporium species -as above. Younger conidiophores & conidia stain more intensely with the LPCB while the mature structures have developed the pigmentation.
(LPCB, DMD-108, 1000X)
Cladosporium species -the structures easily dis-articulate (break up) and it was difficult to keep them intact regardless of using the adhesive tape technique or slide culture technique.
Short chains of oval, pinmented, conidia are seen.
(LPCB, DMD-108, 1000X)
Cladosporium species - a closer look at the conidiophores bearing round to oval pigmented conidia.
(LPCB, DMD-108, 1000+10X)
Cladosporium species -a single conidia (conidiophore?) seen at the end of a septate hyphae.
(LPCB, DMD-108, 1000X)
Cladosporium species - a structure visible in some of the previous photos is more clearly seen in this picture. Here you can clearly see what is referred to as a "shield cell", because of its resemblance to a warrior's shield. These are conidiophores as you can clearly see chains of conidia extending from them. (LPCB, DMD-108, 1000+10X)
Cladosporium species - `Shield` cell conidiophore and conidia
(LPCB, DMD-108, 1000+10X)
Cladosporium species - another view, as above.
(LPCB, DMD-108, 1000+10X)
Cladosporium species - `Shield`cells and chains of conidia
(LPCB. DMD-108, 1000X)
Cladosporium species - Septate hyphae with conidiophore bearing conidia at its apex. Insert is simply a change of focus. (LPCB, DMD-108, 1000X)
Cladosporium species - okay, one final photo, just for the heck of it!
(LPCB, DMD-108, 1000+10X)
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