Whiskey Fungus: The Black Mould Near Warehouses and the Lincoln County Case

Whiskey fungus is the dark, surface-colonising fungus associated with ethanol vapour around spirit maturation warehouses, but it is neither new nor confined to whiskey. In Lincoln County, Tennessee, the much-reported 2023 dispute led to a halt on one Jack Daniel's barrelhouse under construction over incomplete permitting, not a court ban on warehouse emissions.[1][4][5]

What is whiskey fungus?

The name usually refers to Baudoinia, a genus of fungi associated with the black staining found around spirit warehouses. Researchers describe it as the main member of a community known as “warehouse staining”, including growth on surfaces exposed to ethanol vapour near distilleries and bakeries.[1]

Its territory extends beyond warehouse walls. The scientific record includes construction materials, fences, road signs, outdoor furniture, vehicles, soil, rock and vegetation. With industrial ethanol emissions, researchers describe thick, joined-up, crust-like colonies covering surfaces and causing extensive aesthetic damage.[1]

Baudoinia is a slow-growing saprobic oligotroph: a fungus that obtains nourishment from non-living organic material and can grow with few nutrients. In the laboratory conditions reported in the 2016 study, colonies were dark brown to black and reached no more than 10 mm across after 28 days at 26 °C. Those are culture observations, not a timetable for staining outdoors.[1]

From Cognac walls to a scientific name

The first documented description came from Cognac, France. Richon and Petit described the organism in 1881, naming it Torula compniacensis. The original material came from walls at an eaux-de-vie distillery near the Charente, collected in July that year by A. Baudoin and P. Brunaud.[1]

The organism then remained largely outside scientific attention for about 80 years, with brief study in the 1960s before interest revived in the early 2000s. Scott and colleagues established the genus Baudoinia in 2007, honouring Antonin Baudoin's early contributions to understanding warehouse staining.[1][2]

Story box: The black walls of Cognac

How ethanol feeds the fungus

The connection with whiskey begins with ethanol escaping from maturing spirit, often called the angels' share. That relationship also appears in the Kentucky litigation, where a homeowner alleged that ethanol escaping from barrels fed the black film covering his property.[8]

Laboratory work by Ewaze, Summerbell and Scott in 2008 provides a more precise explanation. Ethanol stimulated germination, with an optimum reported at about 10 parts per million when delivered as vapour. Higher concentrations strongly inhibited growth: the relationship was not simply “more alcohol, more fungus”.[3]

The researchers also found that ethanol entered central metabolism through alcohol dehydrogenase and acetaldehyde dehydrogenase, enzymes involved in processing alcohol and its breakdown products. The later 2016 paper described ethanol vapour as affecting nutrition, initiating germination and inducing protection against stress, while noting that the underlying mechanisms remained unknown.[1][3]

The 2007 study reported Baudoinia on surfaces exposed to temperature swings, humidity and airborne ethanol. It also found increased heat resistance after brief exposure to heat below a lethal level. Together, these observations describe an organism adapted to demanding surface conditions, rather than a fungus dependent on a whiskey warehouse alone.[2]

One familiar name, five lineages

Calling every example Baudoinia compniacensis overlooks the findings of the 2016 study. Using multilocus DNA sequencing, researchers examined 19 strains from North America, South America, the Caribbean, Europe and the Far East, identifying five lineages and naming four new species.[1]

These were B. antilliensis, associated with Barbados and Trinidad; B. caledoniensis, with Scotland; B. orientalis, with Korea; and B. panamericana, with Canada, the United States, Argentina and one Scottish barrel bung. These are the study's findings, not an exhaustive map of where each species can occur.[1]

The Scottish material included building surfaces at Willowyard, Beith, and mortar from a spirit ageing warehouse at Kilmalid, Dumbarton. The researchers also suggested that moving used whisky barrels could spread Baudoinia, because it occurs on used barrels. That is a proposed route of dispersal, not proof of how any particular site became colonised.[1]

What happened in Lincoln County?

In January 2023, Christi Long and Patrick Long, owners of an event venue near Jack Daniel's barrelhouses in Lincoln County, sued county zoning officials. Their argument concerned whether the barrelhouses had the necessary permits. Brown-Forman, Jack Daniel's owner, was not named in the suit.[4][5]

Reports described six barrelhouses already built and a seventh under construction. WhiskyCast reported on 2 March 2023 that Chancellor J. B. Cox found the permitting process had never been fully completed and ordered zoning officials to issue a stop work order on the warehouse under construction.[5]

The press account described that building's permit as needing to be rescinded until the necessary permits were obtained. The important distinction is between stopping construction over permitting and deciding the wider questions surrounding fungus, emissions or neighbouring properties. The reported order concerned the former.[4][5]

Brown-Forman spokesperson Svend Jansen said the company respected the ruling and would work with Lincoln County on updated permits. Jack Daniel's general manager Melvin Keebler separately said the company complied with local, state and federal regulations concerning barrelhouse design, construction and permitting.[4][5]

Neighbours, through their attorney Jason Holleman, wanted air filtration on the barrelhouses. Company representative Donna Willis said filters could affect the whiskey's flavour. That was the company's position, not a demonstrated sensory finding in the research presented here.[4][5]

What the earlier Kentucky cases established

The Kentucky disputes concerned another question: whether federal air pollution law prevented neighbours from pursuing state common law claims. That is different from deciding whether a warehouse had received the correct local permits.

In Miller, the Kentucky Supreme Court expressly limited its holding to allowing the state law damages claims to proceed. It refused the requested injunction, explaining that controlling the alleged nuisance through an injunction was inappropriate where the state had already specifically balanced the relevant factors.[8]

Permission to pursue a claim is not the same as winning it. Nor does the reported Lincoln County construction order amount to a general prohibition on ethanol emissions from whiskey warehouses.[5][8]

Property damage and health are separate questions

The 2016 scientific paper describes extensive aesthetic damage from crust-like growth. Researcher James A. Scott, who helped name the genus, called the fungus “pretty destructive” in the press account. Company representative Donna Willis instead said it did not damage property and could be washed off.[1][4]

These statements should retain their attribution rather than being merged into an agreed assessment. Visible staining, the burden of removing it and assertions about property damage are not interchangeable with evidence about human health.

Scott said the fungus did not appear to have a negative effect on human health, but also said he knew of no research specifically examining exposure effects. Willis said studies showed it was not hazardous. Neither statement supplies the missing health evidence needed here to establish harm or harmlessness.[4]

Verdict: Disputed

Claim: The company and researcher gave differing accounts of the fungus's effects on property and health.

What the record shows: Willis said the fungus did not damage property and was not hazardous; Scott called it destructive but did not see evidence of health harm.[4]

Evidence against or gap: Scott knew of no research specifically on exposure effects. The sources checked do not establish health harm or harmlessness.[4]

Earliest known source: Not reliably established. The supplied press account has a URL dated 4 March 2023.[4]

Source: The Boston Globe account, URL dated 4 March 2023.

Last checked: November 2026; the exact day is not reliably established.

Three misconceptions to leave behind

• It is a new problem. Recent coverage brought attention to something scientifically described in Cognac in 1881.[1]
• It grows only around whiskey. The research also identifies staining near other distilleries and bakeries exposed to ethanol vapour.[1]
• Jack Daniel's was sued and lost an emissions case. The Lincoln County suit named county zoning officials, and the reported order stopped one construction project over permitting.[4][5]

Where to go next

• The Chemistry of Whisky Flavour: explore another part of the science behind whisky.
• Terroir in Whisky: Does Place Matter?: examine the evidence behind claims about place.
• Rapid Ageing and Accelerated Maturation: What the Science Says: distinguish maturation research from broader claims.

Sources

1. Scott, J. A. and colleagues. Multilocus DNA sequencing of the whiskey fungus reveals a continental-scale speciation pattern. Persoonia 37, 13 to 20, 2016. https://repository.naturalis.nl/pub/611850/PERS2016037001002.pdf

2. Scott, J. A., Untereiner, W. A., Ewaze, J. O., Wong, B. and Doyle, D. Baudoinia, a new genus to accommodate Torula compniacensis. Mycologia 99(4), 592 to 601, 2007. Europe PMC record. https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=EXT_ID:18065010%20OR%20EXT_ID:18692370&resultType=core&format=json

3. Ewaze, J. O., Summerbell, R. C. and Scott, J. A. Ethanol physiology in the warehouse-staining fungus, Baudoinia compniacensis. Mycological Research 112(11), 1373 to 1380, 2008. Europe PMC record. https://www.ebi.ac.uk/europepmc/webservices/rest/search?query=DOI:10.1016/j.mycres.2008.05.003&resultType=core&format=json

4. The Boston Globe. Whiskey fungus fed by Jack Daniel's encrusts Tennessee town. URL dated 4 March 2023; byline and publication date not shown on the page, as recorded in the fact sheet. https://www.bostonglobe.com/2023/03/04/nation/whiskey-fungus-fed-by-jack-daniels-encrusts-tennessee-town/

5. WhiskyCast. Whisky fungus lawsuit halts work on Jack Daniel's warehouse. 2 March 2023. https://whiskycast.com/whisky-fungus-lawsuit-halts-work-on-jack-daniels-warehouse/

6. Wright, W. and Campbell, C., Mitchell, Williams, Selig, Gates & Woodyard. Whiskey Aging Emissions: Supreme Court of Kentucky Addresses Whether Clean Air Act Preempts Common Law Claims. JD Supra, 18 December 2017. https://jdsupra.com/legalnews/whiskey-aging-emissions-supreme-court-27268

7. Supreme Court of Kentucky. Brown-Forman Corporation v. George Miller, No. 2014-SC-000717-DG, rendered 28 September 2017. Opinion reproduced by HallApproved. https://hallapproved.com/ky/cases/supreme/2017/4437750/

This desk-researched article uses the supplied verified fact sheet, distinguishing scientific findings, attributed company statements, press reporting and court material.

Last checked: November 2026