Yeast Art

Bianca Alley, Omega Yeast’s Orders and Process Coordinator joined the Omega Yeast staff back in 2017, when it was less than quarter of the size it is today. 

Her longest role was as Lab Manager, where a significant part of her work was devoted to beginning the inoculates that are carefully grown into large custom-sized pitches daily. Starting from a slant, she inoculated small flasks next, and from there pitches could be scaled up to truly exponential proportions. The largest pitch propagated regularly at Omega is sized for hundreds of barrels.

She was also responsible for streaking new strains in preparation for the ‑80°C deep freeze that holds Omega Yeast’s many yeast libraries in cryo-suspension — like their commercial catalog and the strains they privately bank for breweries. And she poured and read the plates that the QC team uses to constantly monitor yeast in production. It’s these two things together that inspired her unique hobby.

“I got used to anticipating the various yeast colors on WLN plates. The first plate I ever drew was when we got the new Omega Yeast logo. There was an Extra WLN plate so I thought, lets see if I can trace it in yeast.”

The variation in color that yeast show when picking up bromocresol green dye on WLN plates is the characteristic that defines its use as a differential plate media. Bromocresol green is a pH indicator. At a starting pH of around five or six, it is blue. When the yeast begin to grow and consume the dextrose in the agar, the pH drops and the dye starts to shift from blue to green and yellow on the plate. In addition, the yeast themselves take up the dye and do so differently by strain, so different yeast colonies are visually differentiated by a spectrum of colors from light to dark and in mostly blues and greens.

“I very rarely use the same strains for every plate. I know that West Coast Ale I (Omega Yeast’s Chico strain) is going to be dark blue, but mostly I just take whatever has been plated by QC after they’re done with testing and sample from what’s there. They are almost always Sacch. strains. Sometimes if I don’t have enough variation in color I will pester them to look out for a color the next day.”

The palette she has to choose from is wider than you might think. ​“Strains vary from white to dark blue and everything in between. And I do have access to red, for example, from W303, something we use for malto plating to detect STA+.” From first inspiration, she has since moved on to more complex subjects. 

“I made Bernie in a chair with the mittens, a meme that was going around at the time, it was a huge hit. Lance posted it on our socials. And because he thought it was neat, I made a portrait for him on his birthday. Since then, I’ve opened it up to everyone I work with; if they want a plate they just have to write their birthday in my calendar and I’ll make it.”

There are obviously many layers of difficulty in using a live medium on an organic medium. Not only is Bianca’s color palette tied to the shades of bromocresol-green certain yeast take up and a few other colors from other sources, the drawings have a limited life span.

As the yeast continue to grow, the image can be obscured by overgrowth. Certain yeast could also fail to grow and the image could be incomplete, or colonies can mix and express a different color than planned. Lastly, the plates themselves will eventually be permissive of non-yeast cultures which disrupts the image in another way: 

“The plate will reach ideal growth at day 3 and may continue to grow from there. Anything after 3 days on can be susceptible to mold. Sometimes between day 1 and 3 more details or adjustments are needed if a strain did not grow or wasn’t filled in enough.”

Besides meticulous attention to detail and a steady hand, Bianca’s process involves taking an inspiration photo, and resizing it so that the object of the photo fits within a standard 90 mm plate. She uses that image as her guide.

“Once I have good size-to-plate ratio for the image, I start to draw. I mostly use the tip of a pipette to do the actual drawing. I draw dark colors first then move from darkest to lightest. It is extremely important not to cross strains as the colors will blend. Growth will start to happen in as little as 24 hrs. In 3 days: bam! It’s plate art.”

“Not every plate is a winner,” she says, ​“but they have gotten much better over time!”