Extraordinary images of Aspergillus restrictus
By GAtherton

In 2017, the Dutch Central Bureau of Fungal Cultures was renamed the Westerdijk Fungal Biodiversity Institute, after Johanna Westerdijk. Westerdijk was the first female professor of The Netherlands and director of the centre from 1907 to 1952. She had a great interest in fungi and, under her leadership, the institute’s collection grew to be the largest in the world. A century on from her appointment as professor, Westerdijk’s accomplishments were celebrated with the centre’s renaming and the unveiling of several extraordinary images of Aspergillus restrictus.

A. restrictus is a mould that can grow in environments with very limited water. The species is often found in indoor air and house dust, and is considered a potential cause of respiratory issues; A. restrictus can also contribute towards cereal and cotton rot. In this project, high resolution images of the species were taken at various magnifications, using both light and electron microscopy. These images, copied below, allow the viewer to zoom in on the structure of the mould at differing levels of detail. This means that we can explore the various stages of fungal growth, from different angles and magnifications. For reference, simplified diagrams of the Aspergillus life cycle and structure are included first.

Images of Aspergillus restrictus:

An Aspergillus restrictus colony, measuring approximately 1 cm (bar = 1 mm). White aerial hyphae can be seen throughout the colony.[/caption]

 

An image taken closer to the centre of the colony (bar = 0.5 mm). White aerial hyphae and green columnar conidiophores can be seen throughout.

These images, produced by the Westerdijk Fungal Biodiversity Institute, show the structure and development of Aspergillus restrictus in incredible detail. There are several surprising questions and discoveries that arise from this level of detail. For example, the clockwise twisting of conidial rows has not previously been described, and the chemical composition of the material found on the phialide surfaces is unknown. Therefore, this technology not only provides us with these impressive images, but may also lead to further research and greater understanding of the structure and development of fungi. Greater knowledge of Aspergillus growth and function can assist in the development of drugs which impede its growth.

Read the full paper: Jan Dijksterhuis, Wim van Egmond and Andrew Yarwood (2020), From colony to rodlet: “A six meter long portrait of the xerophilic fungus Aspergillus restrictus decorates the hall of the Westerdijk institute.”