In September 2010, not long after the founding of the Firestone & Robertson Distilling Company, Arnold joined the team and went to work looking for yeast. But to do it right, he was going to need a lab. He reached out to local colleges, and Professor Dean Williams of Texas Christian University responded. Williams helped Arnold set up a lab, advised him on using equipment, and even helped him gain adjunct faculty status so he could come and go at the University as needed.
Arnold immediately began collecting samples from the distillery, which is located in a pre-Prohibition brick warehouse. He even took samples from his own home. Arnold applied the samples to petri dishes and waited to see what would grow. The petri dishes, or plates, contained a growing medium similar
to wort, intended to encourage the growth of yeast species suited to fermentation. However, when Arnold examined his first set of plates, none contained a desirable yeast strain.
Because not all yeast species are capable of fermenting the complex sugars within a bourbon mash into alcohol, the three focused specifically on finding Saccharomyces cerevisiae, a variety widely used by brewers and winemakers. Due to millennia of selective pressure, S. cerevisiae has evolved into an effective fermenter of maltose, capable of surviving in an alcohol solution at concentrations deadly to most other bacteria and micro-organisms.
As the search for S. cerevisiae continued, Arnold headed out of Fort Worth to Rancho Hielo Brazos in Glen Rose, Texas. The ranch manager there, as it turned out, happened to have a background in botany. Arnold spent half a day with the ranch manager traversing the property, collecting samples from the dirt and a variety of plants. Back at the lab, the 20 samples he collected netted hundreds of different bacteria and fungi, including yeast.
Once again, Arnold went through the work of isolating each of the yeast strains by plating and re-plating them repeatedly. In the end, the 20 samples Arnold brought back from the ranch yielded 100 separate yeast strains. To whittle that number down to a manageable size, he used a technique called Polymerase Chain Reaction to isolate the DNA of each strain. Upon analysis, it turned out 11 of the 100 strains were S. cerevisiae. Arnold checked his notes, and discovered that all 11 came from just three sources on the ranch: a cactus fruit, an oak tree and a pecan tree.