In the yeast Saccharomyces cerevisiae, trehalose-6-phospahte synthase (Tps1) and trehalose-6-phosphate phosphatase (Tps2) are the main proteins catalyzing intracellular trehalose production. In addition to Tps1 and Tps2, two putative regulatory proteins with less clearly defined roles also appear to be involved with trehalose production, Tps3 and Tsl1. While this pathway has been extensively studied in laboratory strains of S. cerevisiae, we sought to examine the phenotypic consequences of disrupting these genes in wild strains. Here we deleted the TPS1, TPS2, TPS3 and TSL1 genes in four wild strains and one laboratory strain for comparison. Although some tested phenotypes were not shared between all strains, deletion of TPS1 abolished intracellular trehalose, caused inability to grow on fermentable carbon sources and resulted in severe sporulation deficiency for all five strains. After examining tps1 mutant strains expressing catalytically inactive variants of Tps1, our results indicate that Tps1, independent of trehalose production, is a key component for yeast survival in response to heat stress, for regulating sporulation, and growth on fermentable sugars. All tps2Δ mutants exhibited growth impairment on non-fermentable carbon sources, whereas variations were observed in trehalose synthesis, thermosensitivity and sporulation efficiency. tps3Δ and tsl1Δ mutants exhibited mild or no phenotypic disparity from their isogenic wild type although double mutants tps3Δ tsl1Δ decreased the amount of intracellular trehalose production in all five strains by 17% - 45%. Altogether, we evaluated, confirmed, and expanded the phenotypic characteristics associated trehalose biosynthesis mutants. We also identified natural phenotypic variants in multiple strains that could be used to genetically dissect the basis of these traits and then develop mechanistic models connecting trehalose metabolism to diverse cellular processes.

With the sustained popularity of hazy IPAs, brewers have explored multiple approaches to maximizing stable haze that will remain in suspension throughout the shelf life of the beer. Our recent investigations into yeast-dependent haze have uncovered specific brewing yeast strains that promote the formation of haze in heavily dry-hopped beer styles. These brewing strains have been termed haze-positive and furthermore, the timing of dry hop additions has been found to be another key factor in producing this stable haze. Classical genetics have identified YIL169C (herein referred to asHZY1) as both necessary and sufficient for the haze-positive phenotype in the yeast strain most widely used for Hazy IPAs.HZY1encodes a candidate glycoprotein and our recent findings suggest it is localized to the cell wall through a GPI anchor. Surprisingly, using long-read sequencing data we uncovered extensive genetic variation inHZY1across brewing strains. The haze-positive phenotype correlates with an expansion in the N-terminal serine-rich region. We propose that theHZY1glycoprotein is a critical component to yeast-dependent colloidal haze and the genetic variation in this locus contributes the range of haze phenotypes observed across industrial brewing strains.