Industrial brewing yeast engineered for the production of primary flavor determinants in hopped beer

Abstract

Flowers of the hop plant provide both bitterness and “hoppy” flavor to beer. Hops are, however, both a water and energy intensive crop and vary considerably in essential oil content, making it challenging to achieve a consistent hoppy taste in beer. Here, we report that brewer’s yeast can be engineered to biosynthesize aromatic monoterpene molecules that impart hoppy flavor to beer by incorporating recombinant DNA derived from yeast, mint, and basil. Whereas metabolic engineering of biosynthetic pathways is commonly enlisted to maximize product titers, tuning expression of pathway enzymes to affect target production levels of multiple commercially important metabolites without major collateral metabolic changes represents a unique challenge. By applying state-of-the-art engineering techniques and a framework to guide iterative improvement, strains are generated with target performance characteristics. Beers produced using these strains are perceived as hoppier than traditionally hopped beers by a sensory panel in a double-blind tasting.

The Smell of Synthetic Biology: Engineering Strategies for Aroma Compound Production in Yeast

“…As already shown with the development of a hoppy yeast [86], many of the strategies employed and discussed here could easily be used to engineer aroma development in strains involved in the fermented beverage industry [95][96][97]. The engineering strategies should not, however, interfere with all other processes involved in fermentation.…”

“…Indeed, it is perfectly suited for such an approach to target the production levels of a single metabolite. This is in contrast, however, to recent work in aroma compound development in yeast as part of an alcoholic beverage set-up, where hops flavour (a combination of geraniol and linalool) was introduced in yeast for beer production [86]. An elegant DBTL approach was followed to build strains with ideal hops flavour (similar to commercial beer).…”

“…The eventual goal -especially with the advent of genome or biofoundries -is to curtail human input and allow for automation and machine learning to dominate proceedings. Adapted from [86,82]. Allosteric transcription factor sensor.…”

The Smell of Synthetic Biology: Engineering Strategies for Aroma Compound Production in Yeast

“…Indeed, it is perfectly suited for such an approach to target the production levels of a single metabolite. This is in contrast, however, to recent work in aroma compound development in yeast as part of an alcoholic beverage set-up, where hops flavour (a combination of geraniol and linalool) was introduced in yeast for beer production [87]. An elegant DBTL approach was followed to build strains with ideal hops flavour (similar to commercial beer).…”

“…The eventual goal-especially with the advent of genome or biofoundries-is to curtail human input and allow for automation and machine learning to dominate proceedings. Adapted from [83,87].…”