littlemicrobiologistsstuff

[littlemicrobiologistsstuff]

➡️Mycobacterium gordonae is a species of Mycobacterium named for Ruth E. Gordon. It is a species of the phylum actinobacteria (Gram-positive bacteria with high guanine and cytosine content, one of the dominant phyla of all bacteria), belonging to the genus Mycobacterium.

✔️Gram-positive, nonmotile and moderate to long acid-fast rods.

Commonly found in tap water and soil. Casual resident in human sputum and gastric lavage specimens.

✔️Colony characteristics

Smooth, with yellow or orange scotochromogenic colonies. Even though they are scotochromogenic pigment is intensified by growing in continuous light.

✔️Physiology

Growth on Löwenstein-Jensen medium and Middlebrook 7H10 agar within 7 or more days at 37 °C (optimal 25 °C).

Does not grow in the presence of ethambutol (1 mg/l), isoniazid (10 mg/l) and sodium chloride (5%).

Some strains can grow using carbon monoxide as a carbon and energy source.

✅Differential characteristics

A commercial hybridisation assay (AccuProbe) to identify M. gordonae exists.

Intraspecies variability in 16S r DNA Sequence.

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[littlemicrobiologistsstuff]

Syncephalastrum sp.

Syncephalastrum is a filamentous fungus that is commonly isolated from soil and animal feces particularly in tropical and subtropical areas. It is a heterothallic fungus and requires a mating strain to produce zygospores. Syncephalastrum is commonly considered as a contaminant. It is very rarely associated with human disease.

Syncephalastrum is a very rare causative agent of human zygomycosis .It has so far been isolated in cases of cutaneous infection and otomycosis.

Colonies of Syncephalastrum grow very rapidly and fill the petri dish or culture tube. Maximum growth temperature is 40°C. The texture is wooly to cotton candy-like. From the front, the color is white initially and turns to dark gray to black in time. Reverse is pale or yellowish-brown .

Broad (4-8 µm in diameter), nonseptate or sparsely septate hyphae, sporangiophores, merosporangia (finger-shaped, tubular sporangia), (mero)sporangiospores (=merospores), and rhizoids are visualized. Septation of the hyphae is mostly observed as the culture gets old. Sporangiophores are frequently branched and rather short. They end up in a vesicle (80 µm in diameter). Around this vesicle are the merosporangia (4-6 x 9-60 µm), which are filled with linear series (chains) of sporangiospores. Each merosporangium contains a single row of 3-18 merosporangiospores. Merosporangiospores (3-7 µm, may rarely reach 10 µm in diameter) are one-celled and spherical to cylindrical in shape.

Syncephalastrum differs from Aspergillus by the presence of merosporangia and absence of phialides.

📸 chris_the_biologist01 (insta)