Hybridization of Saccharomyces cerevisiae Sourdough Strains with Cryotolerant Saccharomyces bayanus NBRC1948 as a Strategy to Increase Diversity of Strains Available for Lager Beer Fermentation

Abstract

The search for novel brewing strains from non-brewing environments represents an emerging trend to increase genetic and phenotypic diversities in brewing yeast culture collections. Another valuable tool is hybridization, where beneficial traits of individual strains are combined in a single organism. This has been used successfully to create de novo hybrids from parental brewing strains by mimicking natural Saccharomycescerevisiae ale × Saccharomyceseubayanus lager yeast hybrids. Here, we integrated both these approaches to create synthetic hybrids for lager fermentation using parental strains from niches other than beer. Using a phenotype-centered strategy, S. cerevisiae sourdough strains and the S. eubayanus × Saccharomyces uvarum strain NBRC1948 (also referred to as Saccharomyces bayanus) were chosen for their brewing aptitudes. We demonstrated that, in contrast to S. cerevisiae × S. uvarum crosses, hybridization yield was positively affected by time of exposure to starvation, but not by staggered mating. In laboratory-scale fermentation trials at 20 °C, one triple S. cerevisiae × S. eubayanus × S. uvarum hybrid showed a heterotic phenotype compared with the parents. In 2 L wort fermentation trials at 12 °C, this hybrid inherited the ability to consume efficiently maltotriose from NBRC1948 and, like the sourdough S. cerevisiae parent, produced appreciable levels of the positive aroma compounds 3-methylbutyl acetate (banana/pear), ethyl acetate (general fruit aroma) and ethyl hexanoate (green apple, aniseed, and cherry aroma). Based on these evidences, the phenotype-centered approach appears promising for designing de novo lager beer hybrids and may help to diversify aroma profiles in lager beer.

Autochthonous Biological Resources for the Production of Regional Craft Beers: Exploring Possible Contributions of Cereals, Hops, Microbes, and Other Ingredients

“…Among those, S. cerevisiae S-38 has shown physical-chemical, volatile, and sensory characteristics comparable to the commercial strain Safale S-33 (Fermentis, Lesaffre, Marcq-en-Baroeul, France) [83], whereas S. cerevisiae S-42 had higher ethanol content, lower pH, and a higher content of esters [82]. While Catallo et al [85] used a sourdough strain as a parental strain in a de novo hybridisation to obtain a hybrid for lager beer fermentation. The authors reported that the hybrid inherited the ability to produce positive aroma compounds, such as 3-methylbutylacetate, ethyl acetate, and ethyl hexanoate by the sourdough strain, together with the efficient utilisation of maltotriose from the other parental strain [85].…”

“…While Catallo et al [85] used a sourdough strain as a parental strain in a de novo hybridisation to obtain a hybrid for lager beer fermentation. The authors reported that the hybrid inherited the ability to produce positive aroma compounds, such as 3-methylbutylacetate, ethyl acetate, and ethyl hexanoate by the sourdough strain, together with the efficient utilisation of maltotriose from the other parental strain [85].…”

Increased volatile thiol release during beer fermentation using constructed interspecies yeast hybrids

“…Here, we aimed to generate brewing yeast strains with enhanced ability to release volatile thiols during wort fermentation through interspecific hybridization of S. cerevisiae brewing strains with strains of S. uvarum or S. eubayanus . Interspecific hybridization has been used extensively for brewing yeast strain development in the past decade [28–30, 55, 56]. It allows for combining traits from diverse parent strains, can be performed without any genetic engineering, and hybrids may in some cases exhibit hybrid vigour, where they outperform the parent strains in certain traits [7].…”

Sour Beer as Bioreservoir of Novel Craft Ale Yeast Cultures

“…Spore viability was determined by asci dissection and monospore clone constitution as previously reported [ 46 ], according to the following equation: Spore Viability % = (n° of vital monosporic cultures/n° of dissected spores) × 100, …”

“…For each strain, at least eight asci were dissected. Both wild strains and their monospore derivatives were genotyped for the MAT locus according to Catallo et al [ 46 ]. Strains BY4742 and BY4743 ( Table 1 ) were used as positive MATα and MATα / MAT a controls, respectively.…”