SBIR-STTR Award

Company: Berkeley Fermentation Science Inc. (BFS); DBA Berkeley Yeast (BY)Title: Engineering Saccharomyces cerevisiae for increased biotransformation and production of tropical flavors from agricultural products Tropical fruit flavors are highly desirable in the fermented beverage market. The popularity of these flavors is especially evident in the beer industry where sales of beers made with tropical flavoring hops primarily grown in the American Pacific Northwest and Australia/New Zealand has skyrocketed in the last decade. While demand for these beers and the tropical flavoring-hops used to make them has increased in recent years extreme weather events like droughts and high winds have simultaneously threatened and in some cases damaged U.S. flavoring-hop harvests. As increasingly dry and adverse weather events are predicted to become more frequent due to climate change U.S. hop harvests hop farmers and the production of in- demand beer styles will become increasingly threatened in coming years. While efforts are underway to support the $500M/yr American hop industry through the breeding of more resilient and drought tolerant hop cultivars current drought-tolerant plants lack the pungent fruity flavor profiles that brewers and beer drinkers demand. In this SBIR application we propose to develop genetically engineered strains of brewers yeast that will produce strong tropical fruit flavors during beer fermentation using non-aromatic precursor molecules already existing in drought-tolerant hops as substrates. Specifically we will engineer yeast for production of three volatile thiol molecules 3MH (guava flavor) 3MHA (passion fruit) and 4MMP (black currant) each of which is a major contributor to the tropical flavor notes of currently popular hopsvarietals. As differing ratios of 3MH 3MHA and 4MMP molecules impart distinctive flavors in beer we will construct a set of brewing yeast strains in which each strain produces distinct quantities of these three volatile thiols. This set of strains will provide brewers with an easily scalable toolkit that produces a diversity of tropical fruit flavored beers using American-grown non-aromatic drought tolerant hops as substrates. This work will build upon our prior success engineering brewing yeast strains for enhanced 3MH biosynthesis during beer fermentation. In our proposed Phase I research we will develop yeast strains that produce varying ratios of 3MH to 3MHAduring fermentation then test the consumer acceptance and commercial potential of this technology. In Phase II work we will develop strains that additionally produce4MMP during fermentation then increase production of all three thiols so as to be comparable to the concentrations achieved through addition of popular flavoring hopvarietals. The end result of Phase II work will be a set of strains that produce distinct marketable concentrations of 3MH 3MHA and 4MMP during beer fermentation. This technology will provide valuable tools that help the beer and hop industries meet consumer demand while insulating them from the threat of droughts and severely reduced hop harvests.