Evolution-based strategy to generate non-genetically modified organisms Saccharomyces cerevisiae strains impaired in sulfate assimilation pathway

Abstract

Aims: An evolution‐based strategy was designed to screen novel yeast strains impaired in sulfate assimilation. Specifically, molybdate and chromate resistance was used as selectable phenotype to select sulfate permease–deficient variants that unable to produce sulfites and hydrogen sulfide (H2S). Methods and Results: Four Saccharomyces cerevisiae parent strains were induced to sporulate. After tetrad digestion, spore suspensions were observed under the microscope to monitor the conjugation of gametes. Then, the cell suspension was inoculated in tubes containing YPD medium supplemented with ammonium molybdate or potassium chromate. Forty‐four resistant strains were obtained and then tested in microvinifications. Three strains with a low sulfite production (SO2 <10 mg l−1) and with an impaired H2S production in grape must without added sulfites were selected. Conclusions: Our strategy enabled the selection of improved yeasts with desired oenological characteristics. Particularly, resistance to toxic analogues of sulfate allowed us to detect strains that unable to assimilate sulfates. Significance and Impact of the Study: This strategy that combines the sexual recombination of spores and application of a specific selective pressure provides a rapid screening method to generate genetic variants and select improved wine yeast strains with an impaired metabolism regarding the production of sulfites and H2S.

Exploration of Sulfur Assimilation of Aspergillus fumigatus Reveals Biosynthesis of Sulfur-Containing Amino Acids as a Virulence Determinant

“…Moreover, the sB⌬ strain grew poorly on sulfite (SO 3 2Ϫ ) and thiosulfate, suggesting that the SB transporter is also involved in the uptake of partially reduced inorganic S sources. In addition, the deletant became resistant to chromate, a toxic sulfate analogue that is commonly used to isolate and validate mutants impaired in the uptake of sulfate (51,52,59). As expected, AfS177 grew normally on organic S sources such as methionine or cysteine.…”

Qualitative and quantitative screening of theβ-glucosidase activity inSaccharomyces cerevisiaeandSaccharomyces uvarumstrains isolated from refrigerated must

“…; De Vero et al . , ). Although the mating frequency for crossings between S. cerevisiae and S. uvarum is low (Solieri et al .…”

Genetic variation and expression changes associated with molybdate resistance from a glutathione producing wine strain of Saccharomyces cerevisiae

“…Among the events conferring resistance to sulfate toxic analogues, a mutation in the high-affinity permeases encoded by the genes SUL1 and SUL2 is one of the most probable [12–14]. In this case, the subsequent impaired assimilation of sulfate [36] can lead to altered GSH production. GSH biosynthesis in S .…”