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Published: July 8, 2019

Eurotium

Most species of fungi have intricate and complicated life cycles. Many of them exhibit pleomorphic life cycles, meaning that they can exist in two forms – the anamorph form, which reproduces asexually and produces genetically identical copies of itself, and the teleomorph form which arises when two genetically compatible fungi fuse and produce fruiting bodies. The teleomorph forms reproduce sexually, meaning that the genomes of the two fungi combine, producing genetically unique organisms.

What is Eurotium?

Eurotium is a genus that comprises the teleomorph forms of several Aspergillus species, notably the Aspergillus glaucus group. However, although teleomorph forms of Aspergillus have been described in at least eight genera, Eurotium is arguably the most significant to humans as they are a common agent of food spoilage [1]. There are 81 species described in this genus [2]. Significant species include E. amstelodami, E.chevalieri, E. herbariorum and E. repens.

Eurotium aspergillus glaccus
Eurotium aspergillus glaccus

One organism – two names?

Yes, it may seem strange and confusing at first but in the world of fungi it is not uncommon for the anamorph and teleomorph forms of the same organism to have different names. For example, the mold known as Aspergillus glaucus can mature into the fungus known as Eurotium herbariorum [3]. The situation is analogous to a strawberry maturing into a banana and highlights how far removed the kingdom of fungi is from plants or animals and how difficult and confusing their taxonomy can be.

This concept of dual nomenclature was established in 1910, precisely to solve the problem of fungi that have pleomorphic life cycles [4]. The problem is greater than it seems at first. Namely, many fungi reproduce only asexually. Cataloguing fungi would have been easier if they all exhibited both anamorph and teleomorph forms, as there would be no unknowns and no uncertainties over whether a species has a sexual form or not. Furthermore, even if a fungus has a sexual form, it is often rare or can be observed only under specific conditions. In many cases, both the anamorph and teleomorph forms of a fungus were well known to science but the connection between them remained unknown for years.

In recent years, the rise of molecular methods have changed fungal systematic drastically and have rendered the dual nomenclature system a thing of the past. Namely, researchers adopted a “one fungus, one name” principle in 2011. However, although the dual nomenclature system is not based on evolutionary relationships, it is quite useful in many domains, such as plant pathology, medical mycology and food microbiology. Teleomorphs are often grouped by their morphology and physiology – such classification is very useful in a practical sense.

eurotium cristatum
< rel="nofollow" href="https://www.flickr.com/photos/chadao/28198313680" target="_blank">Eurotium cristatum

For example, consider these 3 well known genera of Aspergillus teleomorphsEurotium, Neosartorya and Emericella. Eurotium species are xerophiles, and can spoil practically any low water activity (dry or concentrated) material. Neosartorya species on the other hand are not xerophilic. They are thermophiles that inhabit decaying vegetation. They have exceptional heat resistance, causing spoilage of pasteurized products. Emericella species are neither xerophilic nor thermophilic, and are soil inhabiting fungi rarely observed anywhere else. If a species is reported as Eurotium, food industry professionals immediately know that they are dealing with a xerophilic organism; if it is reported as Neosartorya, they will know that the spoilage problem will not be solved by pasteurization. Therefore, simply lumping all of these teleomorph forms into the Aspergillus genus would cause a loss of information, which is why the dual vs singular nomenclature system is still a topic of debate amongst mycologists [4].

Where can Eurotium be found?

Eurotium species are well known as osmotolerant colonizers of dry substrates or substrates with low water activity due to high amounts of dissolved salts or sugars. They have been detected in water with salinity above 17%. Many of them can grow at water activities below 0.75, some have even been observed to grow at a value of 0.64 [5]. They are often encountered in the food industry and are common agents of food spoilage. They are also particularly relevant in the context of animal feed, as poorly stored grains provide an ideal environment for these xerophilic fungi [6].

They are also major colonizers of household dust, where they may grow on relatively dry shed-skin scales. Growth on leather, textiles and books stored in slightly humid conditions, as well as other semidry surfaces, is common. E. herbariorum was the third most common fungus isolated from samples of moldy gypsum wallboard taken from buildings in USA and Canada. In North America, Eurotium species frequently occur in insulation, gypsum wallboard, composite wood and ceiling tiles. They are also often isolated from air handling unit filters, carpets, painted surfaces, ceramic tiles and concrete efflorescences. Due to their ability to thrive even at relatively low moisture levels they are regarded as primary colonizers. Eurotium species are considered to be the most common members of the Ascomycetes encountered in indoor environments, on walls and other surfaces and in house dust [7].

Is Eurotium dangerous?

The health effects of Eurotium species are poorly studied in comparison to their Aspergillus counterparts. Still it has been known to cause infections of the ears and eyes, subcutaneous infections, mycetoma [3], allergic bronchopulmonary mycosis [8] and was confirmed to be the cause of a cerebral abscess in an otherwise healthy female [3]. Also, increased counts of Eurotium in water damaged schools were associated with an increased prevalence of asthma in the children that frequented them [9].

Many clinical records offer incomplete taxonomic description and are unclear on whether it is the anamorph or the teleomorph that caused the infection. However it is likely that a significant number of opportunistic mycoses, especially keratitis cases, are indeed caused by Eurotium species, although clearly the probability of involvement of the thermotolerant E. amstelodami is much greater than that of the relatively uncommon and less thermotolerant E. herbariorum/A. glaucus [3].

Indeed, it is pertinent to mention the health effects of A. glaucus and its closest relatives, as they are only separated from Eurotium species by a stage in their life cycle. A. glaucus has mostly been associated with a range of ocular infections, especially after traumatic injury. There have also been other types of infections associated with A. glaucus including cerebral, orofacial, cardiovascular, pulmonary, nasal and ear infections, although these are rare. There has only been one recorded fatality due to A. glaucus. An otherwise healthy and immunocompetent adult succumbed to a brain infection caused by A. glaucus, which eventually proved to be deadly despite aggressive antifungal treatment [10].

How to get rid of Eurotium?

If there is any mold in your home or workplace, getting rid of it should be a top priority. While it’s true that some species are more dangerous than others, it’s also fair to say that mold usually grows in mixed colonies, meaning that one of the more hazardous molds will eventually develop. Outside of mold grown in the lab, it is rare that a mold growth consists only of one species. The presence of a primary colonizer like Eurotium is like a calling card for other molds to develop on the now habitable substrate.

While removing small colonies can be seen as a DIY job, larger deeply rooted mold infestations usually require the help of professionals. Large infestations are typically caused by an underlying moisture related issue. Sometimes it can be nothing more than a leaky pipe or a clogged gutter, but sometimes it can be related to poorly planned construction, drainage or isolation or the use of inadequate construction materials. As fixing these issues can be costly, enlisting the help of a professional mold removal service to diagnose the issue before you spend a large amount of money can be worthwhile.

Mold busters offer a wide range of mold related services, including air quality testing, dehumidifying, mold testing and mold removal. Armed with 15 years of experience and the latest in mold removal technology, we are capable of removing mold infestations of any size. Our technicians are also able to provide advice on any underlying issues that need to be sorted in order to keep your residence mold free in the future. Call us today to book an appointment.
References

  1. Pitt JI, Hocking AD (2009). Aspergillus and Related Teleomorphs. In: Fungi and Food Spoilage. Springer, Boston, MA, pp 453.
  2. Bensch K (2019). Eurotium. Retrieved from mycobank.org.
  3. Howard DH (2003). Pathogenic Fungi in Humans and Animals. Marcel Dekker, New York. pp 240-498.
  4. Pitt JI, Samson RA (2007). Nomenclatural considerations in naming species of Aspergillus and its teleomorphs. Stud Mycol. 59:67–70.
  5. Butinar L, Zalar P, Frisvad JC, Gunde-Cimerman N (2005). The genus Eurotium – members of indigenous fungal community in hypersaline waters of salterns. FEMS Microbiol Ecol. 51(2):155-66.
  6. Greco M, Pardo A, Pose G, Patriarca A (2018). Effect of water activity and temperature on the growth of Eurotium species isolated from animal feeds. Rev Iberoam Micol. 35(1):39-48.
  7. Flannigan B, Samson RA, Miller JD (2011). Microorganisms in home and indoor work environments: diversity, health impacts, investigation and control. CRC Press. Boca Raton, FL. pp 55-107.
  8. Oshikata C, Watanabe M, Saito A, Ishida M, Kobayashi S, Konuma R, Kamata Y, Terajima J, Cho J, Yanai M, Tsurikisawa N (2017). Allergic Bronchopulmonary Mycosis due to Exposure to Eurotium herbariorum after the Great East Japan Earthquake. Prehosp Disaster Med. 32(6):688-690.
  9. Haverinen U, Husman T, Toivola M, Suonketo J, Pentti M, Lindberg R, Leinonen J, Hyvärinen A, Meklin T, Nevalainen A (1999). An approach to management of critical indoor air problems in school buildings. Environ Health Perspect. 107 Suppl 3:509-14.
  10. Lacqua A, Tom J, Wong L, Dilliberto G (2016). Aspergillus Glaucus. Retrieved from microbewiki.kenyon.edu.