Scopulariopsis brevicaulis (Sacc.) Bainier 1907 - The story of Napoleon's executioner
After his conviction, Napoleon spent the rest of his life in exile on the island of St. Helena, a British overseas territory. Old records from this time indicate that the rooms where he was accommodated were painted green. The so-called “Schweinfurt green”, which is obtained from copper arsenite acetate, was probably used for this purpose. If sufficient moisture and other carbohydrate sources are available, Scopulariopsis brevicaulis is able to break down arsenic-containing paints (such as this copper arsenite acetate) (Gams et al. 2007). This process produces gaseous and toxic trimethylarsine.
During examinations of Napoleon's corpse, high concentrations of arsenic were found in the hair and fingernails, but without the usual evidence of heavy metals. This may indicate arsenic poisoning by trimethylarsine, which in turn may have had its origin in the biological activity of Scopulariopsis brevicaulis (source Wikipedia as of 02.2025). The case described is certainly an exception, which is documented in detail primarily due to the involvement of prominent victims.
However, species from the genus Scopulariopsis and also Scopulariopsis brevicaulis are capable of causing mycoses in humans even without the presence of arsenic-containing dyes (see details in the Medical relevance section). Both non-invasive and invasive mycoses are described in the literature. What is the difference? In non-invasive mycoses, the mold grows on fingernails or toenails, the cornea in the eye or the eardrum, whereas in invasive mycoses, internal organs such as the lungs or brain are affected. Even though these mycoses are more likely to affect people with a weakened immune system, a high detection of Scopulariopsis brevicaulis should be examined by a specialist (source: Atlas of Clinical Fungi 4th Ed. 2020).
Analysis
Picture 1) Front of a Scopulariopsis brevicaulis pure culture on MEA agar. Incubated for eight days at 25 °C. The typical sand-colored colony and its velvety structure are relevant for morphological identification. A yellowish exudate droplet is visible in the center of the colony, which is not always formed and often disappears in older colonies. Older colonies often have a central elevation due to air mycelium. The sand-colored colony is surrounded by a white frayed ring of sterile mycelium (growth zone).
Picture 2) Back of a Scopulariopsis brevicaulis pure culture on MEA agar. Incubated for eight days at 25 °C. A characteristic brown ring can be seen surrounding the center of the colony, which in turn is surrounded by a lighter brown to yellowish ring.
Picture 3) Front of a Scopulariopsis brevicaulis pure culture on DG18 agar. Overall, the colony is only whitish to very slightly brown in color. This is due to the fact that significantly fewer conidiospores are formed on DG18 agar, which are responsible for the coloration in the MEA images (Fig. 1). This is consistent with the literature data that low water availability leads to vegetative growth in Scopulariopsis brevicaulis (Gams et al. 2007).
Taxonomy
Strictly speaking, the mold species Scopulariopsis brevicaulis was already published in 1882 by Saccardo in the “Annales Mycologici 5”. At that time, however, it was still known as Penicillium brevicaule. As biologists have always preferred to take obvious morphological characteristics into account when naming organisms, this was no different here. Translated from Latin, brevicaule means nothing other than “short stalk”. This is undoubtedly an allusion to the fact that the annelids (note that in the case of Scopulariopsis we speak of annelids, not phialides) are bundled together on a short stalk (see Figure 4; light microscope image). In 1907, the species description valid to date was published in the “Bulletin de la Société Mycologique de France” by Bainier with the name Scopulariopsis brevicaulis, which is still valid today (see mykobank.org as of 02.2025).
Routine analysis
In the Compendium of Soil fungi Sec. Ed. (Gams et al 2007), reference is made to a number of publications that have demonstrated vegetative growth (mycelium formation) for Scopulariopsis brevicaulis even at comparatively low water availability. This leads to the conclusion that this is at least partially a xerophilic species that can also grow at low water availability. Xerophilic molds play an important role in the investigation of indoor damage, as they can occur even when surfaces and materials are only occasionally or slightly damp. In the case of other xerophilic species, condensation is often cited as an example (e.g. Aspergillus restrictus species complex). Based on this scientific data, it can be assumed that Scopulariopsis brevicaulis can certainly be seen as a moisture indicator in indoor spaces, even if there is no official declaration from the UBA mold guide (version of 04.2024). From an ecological perspective, Scopulariopsis brevicaulis is described as being found worldwide and can be detected on a wide variety of substrates (e.g. soil, wood, fruit, manure, paper and food) (Food and Indoor Fungi Sec. Ed. 2019).
Scopulariopsis brevicaulis is the first mold within the “Mold of the month format” with a so-called annelid spore production instead of a phialid spore production. An annelid is described as a spore-producing terminal cell that forms conidia in basipetal chains one after the other. These conidia are produced through the identical opening and leave a final ring around the annelid after successful strangulation. Due to this process of the remaining ring (important identification feature), the spore-producing cell elongates as it ages (see definition Food and Indoor Fungi Sec. Ed. 2019).
Medical relevance
According to TRBA 460 (2016:07), the mold species Scopulariopsis brevicaulis is classified in biological risk group 1. However, TRBA 460 refers to a deviating risk for immunocompromised people, as well as a possible allergic reaction and possible mycotoxin production. According to the Atlas of Clinical Fungi (4th Ed. 2020), Scopulariopsis brevicaulis is frequently detected in samples of mold-infested fingernails and toenails, which indicates a keratinolytic property of this species. In addition, a whole series of other cases of Scopulariopsis brevicaulis have been described, most of which are associated with a weakened immune system and other diseases. Invasive mycoses are possible in this species because some of its strains are able to grow at temperatures of around 37°C (optimum growth, however, is at 24 - 30°C). Due to the medical prevalence of Scopulariopsis brevicaulis, a species-specific qPCR protocol was developed in 2016 for the reliable detection of this mold species (Kordalewska et al. 2016).
Light microscope image at 400x magnification
Light microscope image of Scopulariopsis brevicaulis at 400x magnification (plus subsequent digital magnification). The annelids are arranged in small groups on short stalks (Latin brevicaule = short stalk). The annelids are slender and not bulbously thickened. It can be seen that older annelids (at the bottom of the stalk) are slightly longer than younger ones (see description of an annelid). The spores are round and have a diameter of 5-7µm. They are formed in chains that can easily disintegrate. Depending on the spatial orientation of the conidiospores, a flattened base and sometimes a slightly elongated tip can be recognized (identification feature).
Fluorescence image at 400x magnification
Fluorescence image of Scopulariopsis brevicaulis at 400x magnification (plus subsequent digital magnification) stained with acridine orange, the stimulated light is measured at 525nm (hence the green hue). Bright green round objects are the conidiospores, which contain a lot of DNA due to their biological activity and are therefore particularly easy to stain with acridine orange. Annelids and mycelium glow a much weaker green, as they contain less DNA.
Scanning electron micrograph sputtered with gold at about 6127x magnification
Scanning electron micrograph of Scopulariopsis brevicaulis sputtered with gold at about 6127x magnification. The scale bar at the bottom right of the image indicates 10µm. The spore carriers and annelids in particular are compressed by the sputtering process and the vacuum (preparation artifact). Normally the structures mentioned are turgescent and round, without clear deformations. The spores of Scopulariopsis brevicaulis are significantly more stable than those of Penicillium citreonigrum for example as they show no deformation. The spores are round and have the characteristic rough surface. Depending on the spatial orientation, a ring can be seen on the spores, which is clearly visible in light microscopy as a flattened base. This ring is formed when the conidiospores are cut off from the annelid and only becomes visible when the spore chains break down into individual spores.
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