Left Hand Brewing is now suing a yeast distributor in Denver federal court claiming the company’s over-active yeast triggered a $2 million recall of Milk Stout Nitro.

The federal lawsuit was filed on Thursday against White Labs Inc. by Indian Peaks Brewing, which does business as Left Hand Brewing.

Longmont-based Left Hand is seeking compensatory damages for recalled and wasted beer, lost sales and revenue. It is also asking a judge to compensate the stout brewer for damage to its brand and lost market share, the federal lawsuit says.

It is seeking damages of at least $6 million from White Labs, according to the lawsuit filed by Holland & Hart attorneys Maureen Witt, J. Lee Gray and Beau Bump.

Until late 2016, Milk Stout Nitro — nicknamed “America’s Stout” — garnered a significant share of the national and international craft beer market for stout-style beers, the lawsuit says.

But its market share decreased for the first time after White Labs’ tainted yeast caused over-pressurized bottles, broken bottles, off flavors and “disruption of the distinctive nitrogen cascade,” says the lawsuit which was transferred from Boulder District Court.

Left Hand Brewing, 1265 Boston Ave., Longmont, was forced to recall $2 million of beer product including Milk Stout Nitro, Extrovert IPA and Warrior Fresh Hop IPA.

The brewer also destroyed several thousand barrels of unpackaged beer and shut down beer production for more than two weeks in order to disassemble and sanitize all production equipment.

“Left Hand has incurred millions of dollars in monetary damages,” the lawsuit says.

The company said that an investigation discovered that the beer was contaminated by a strain of wild yeast called Saccharomyces cerevisiae variant diastaticus that is known to cause secondary fermentation in beer.

According to the lawsuit, Left Hand was able to trace the source of the wild yeast to White Labs, a Colorado company with its principal place of business in San Diego, Calif. The company had given Left Hand a certificate of quality assurance, the lawsuit says.

A customer complained about abnormally high pressure in his bottle of beer on July 6, 2016, it says. Subsequent genetic testing determined White Labs’ yeast was tainted, causing a secondary fermentation.

The findings were confirmed by MIDI Labs of Newark, Delaware, and the Colorado Department of Public Health and Environment, the lawsuit says. Left Hand shut down its operations in October of 2016, it says. It brought in welding teams to rebuild pipework and set up a new filtration system.

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“Basically every nook and cranny of the brewery was inspected, cleaned, and repaired or replaced,” the lawsuit says.

In 2015, Left Hand was the 39th largest craft brewery in the U.S. with customers in 40 states and eight foreign countries in Europe and Japan, the lawsuit says. The company has 28 Great American Beer Festival medals and 11 World Beer Cup awards. Besides Milk Stout Nitro it makes a number of different products including Wake Up Dead Nitro.

Left Hand subsequently contracted with a new yeast vendor.