Transgene

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Claes Gausmann, yeast geneticist at Carlsberg Laboratory in Copenhagen, tells me that the problem with automating yeast research is akin to the problem with automating fly flipping as described by Jenny Bangham in her work on Drosophila stock centers. It should not be taken for granted that the individual organism—or colony, or bottle, either of which may for these purposes be understood as an “individual” insofar as they are assumed to represent a single type—is indeed a healthy representative in the way it must be to adequately perform its scientific role. Automated methods for perpetuating yeast colonies, like the large robotic colony picker Gausmann shows me, may appear to save a researcher time. Instead, they may cost time and endanger experimental results if the colonies they identify to replicate vary from what they are supposed to be.

This concern may be especially acute for researchers like Gausmann who work with the brewing industry because lager strains are especially prone to chromosome loss. Yeast colonies, visible white spots on agar surfaces, ideally develop from the replication of a single cell and its progeny to form a homogenous clonal population. If any one of those cells loses a chromosome along the way, the resulting colony will have a sectored appearance—a section of what would otherwise be a perfect circle will instead have a different, distinct morphology. An experienced yeast-worker can detect that phenotype and either avoid sampling yeast from that colony or use a very fine needle to dissect one clonal group from the other; Gausmann’s is made of platinum. An automated colony picker, however, may not be able to distinguish and avoid an abnormally shaped colony or may not be able to do so reliably; it certainly cannot derive the additional information from that aberrant that an experienced yeast biologist might. Also, automated colony pickers seem to break a lot.

Gausmann is the most recent member of a lineage of Carlsberg-based yeast researchers beginning with Emil Christian Hansen who, in 1883, publicized the first reports of a method for isolating a “pure culture” of brewers yeast. Hansen’s work famously yielded “Carlsberg bottom-fermenting yeast No. 1,” a reliable brewing strain which improved consistency and quality control at the brewery and established Carlsberg Laboratory as an internationally significant location for scientific research early in the institution’s history. Hansen’s reputation, and Carlsberg’s, stemmed from the capacity of this technique to make yeast singular and stable. In pioneering a strategy to improve beer by reducing the risk of off flavors or stuck ferments from less-than-capable yeast, therefore, Hansen also enabled yeast to become a “model” organism in the sense of a stable target for scientific explanation (Keller, 2003). Becoming a stable, reliable target for scientific explanation in turn enabled yeast to become a model organism in the more familiar sense of an organism assumed to have explanatory value for other less easily studied systems, as well as in the sense of an organism around which a community and shared set of resources have developed. Notwithstanding the many other developments necessary to enable Hansen’s, it is not too far a stretch to say that yeast genetics started with a glass of Danish beer.

Hansen’s work, Gausmann’s work, and even the work of the mostly-disused colony picking robot share a common orientation even beyond yeast. All endeavor to transform this organism—whose colloquial name was once applied to a process seen to be a mystical and uncontrollable force of nature—into a consistent, reliable, unchanging tool. Much the same can be said of many other model organisms. What sets yeast apart is what happens as I walk down the massive central staircase to the front door of the lab from the attic library, tying my scarf against the still-falling snow outside. Claes hands me a dark green plastic bag as he shakes my hand and shows me out. Inside is a bottle of Carlsberg’s Rebrew, a contemporary lager made with yeast propagated from a 133 year-old bottle found in Carlsberg’s cellars, presumably the strain which the company calls “the father to most beers in the world” because it was disseminated so widely. Rebrew proves to be as much a taste of history as one might hope: darker, sweeter, more filling and less “international” in style than its contemporary descendent. If drinking the beer doesn’t add to the data I collected at the Carlsberg library as such, it helps me understand how brewers yeast, the demands placed on it and the demands placed on the researchers who work with it, have changed in the intervening century. Yeast is never only a standardized research tool; it is always also the central mover in affective—and meaningful—sensory experiences.

Reference

Keller, Evelyn Fox. (2003). Making sense of life. Cambridge: Harvard University Press.