Learning about Baudoinia compniacensis was the prompting for a “Botany and Spirits” series, as the story intrigued me so much. A big thank you to Dr. James Scott, Associate Professor from the Dalla Lana School of Public Health at the University of Toronto for sharing the first three images, and a nod of appreciation to Shadle@Wikimedia Commons for a photograph of the phenomenon caused by the organism at Heaven Hill Distillery in Bardstown, Kentucky, USA.
Baudoinia compniacensis is known commonly as the angels’ share fungus or warehouse staining mold. When distilled beverages are aged in wooden barrels, a portion of the liquid is lost to evaporation through the pores of the wood. For a spirit like rum which is distilled in tropical and warm temperate regions, the loss can reach (exceed?) 10% annually, whereas spirits aged in colder climates might lose 1-2%. The alcohol “lost” due to evaporation is called “the angels’ share”.
A decade or so ago, Dr. Scott was contracted by Hiram Walker Distillery in the community of Lakeshore, Ontario to determine whether a mysterious black mold blanketing local buildings and objects (including stainless steel fermenter tanks!) had anything to do with the distillery. Previous attempts by other researchers were either explained away as typical environmental fungi or recognized as a biological stumper. Dr. Scott immediately suspected something different than the typical, and started to track down fungi associated with ethanol. After discovering how to isolate and culture the fungus (the photographs above from Dr. Scott), he began to compare it with other fungi. His initial investigations led him to examine Zasmidium cellare, the cellar fungus, which grows in caves and cellars used for aging wines–but this had to be rejected because it was both different in morphology and grew in a very different environment. Researching in the mycology collections of the National Herbarium of Canada, he and Stan Hughes came across a sample of Torula compniacensis collected from Cognac, France (compniacensis = of Cognac) in the late 19th century. It closely resembled the sooty black mold from Ontario.
Via a colleague, a living sample from Cognac was obtained by Dr. Scott; it was cultured and proved to be a match. But, it didn’t yet have a valid name, as Torula was used for many years as a sort of placeholder genus for different species and genera of black molds, most of which have now been split into separate genera. Torula is now restricted to a very well-defined set of characteristics, and this species did not conform. A new genus was necessary, and so Baudoinia was put forth in 2007 (see: Scott, JA et al. 2007. Baudoinia, a new genus to accommodate Torula compniacensis. Mycologia. 99(4): 592-60. doi: 10.3852/mycologia.99.4.592 ).
The genomic sequence for Baudoinia compniacensis has been completed and the species is described on the Joint Genome Institute’s site: Baudoinia compniacensis. Quoting from the site: “The extremophilic sooty mold Baudoinia compniacensis is the prominent pioneering species in the primary successional community known as “warehouse staining”, where darkly pigmented microbes form dry biofilms on outdoor surfaces periodically subjected to low level exposure to ethyl alcohol vapour, such as those around distilleries, spirit maturation facilities (“bond warehouses”) and commercial bakeries. Pronounced blackening often extends considerable distances from alcohol emission source, indiscriminately colonizing exposed surfaces ranging from vegetation to built structures, sign posts and fences (including those made from glass and stainless steel). Mature colonies are crust-like and scorched in appearance, sometimes reaching 1–2 cm in thickness”.
For a longer version of this story about Baudoinia compniacensis (and where I learned about it), please read the Wired magazine article by Adam Rogers: “The Mystery of the Canadian Whiskey Fungus“. It goes into far more detail than I can in this space, and Adam Rogers knows how to tell the tale.
I find it fascinating that this broadly-distributed organism (it is found around the world wherever distilleries are located) lacked a valid name until the 21st century, and that it was a mystery to many for such a length of time (despite its prominence in areas where it grows). Also intriguing is that it is yet to be seen in nature, where presumably it grows in small colonies associated with naturally-occurring fermentation processes (e.g., rotting fruit). It also is a strong reminder of the importance of well-supported herbaria; had there not been samples of the original collection from France in the National Herbarium of Canada, who can say how the story would have evolved. Fortunately, with the resampling and renaming, new specimens have now been deposited into collections worldwide such as the Microfungus Collection and Herbarium at the University of Alberta.
Additional photographs of this species and examples of “warehouse staining” are available via Wikimedia Commons: Baudoinia compniacensis.