title: Differential hypersaline stress response in Zygosaccharomyces rouxii complex yeasts: a physiological and transcriptional study.
abstract: The Zygosaccharomyces rouxii complex comprises three distinct lineages of halotolerant yeasts relevant in food processing and spoilage, such as Z. sapae, Z. rouxii and a mosaic group of allodiploid strains. They manifest plastic genome architecture (variation in karyotype, ploidy level and Na(+)/H(+) antiporter-encoding gene copy number), and exhibit diverse tolerances to salt concentrations. Here, we investigated accumulation of compatible osmolytes and transcriptional regulation of Na(+)/H(+) antiporter-encoding ZrSOD genes during salt exposure in strains representative for the lineages, namely Z. sapae ABT301(T) (low salt tolerant), Z. rouxii CBS 732(T) (middle salt tolerant) and allodiploid strain ATCC 42981 (high salt tolerant). Growth curve modelling in 2 M NaCl-containing media supplemented with or without yeast extract as nitrogen source indicates that moderate salt tolerance of CBS 732(T) mainly depends on nitrogen availability rather than intrinsic inhibitory effects of salt. All the strains produce glycerol and not mannitol under salt stress and use two different glycerol balance strategies. ATCC 42981 produces comparatively more glycerol than Z. sapae and Z. rouxii under standard growth conditions and better retains it intracellularly under salt injuries. Conversely, Z. sapae and Z. rouxii enhance glycerol production under salt stress and intracellularly retain glycerol less efficiently than ATCC 42981. Expression analysis shows that, in diploid Z. sapae and allodiploid ATCC 42981, transcription of gene variants ZrSOD2-22/ZrSOD2 and ZrSOD22 is constitutive and salt unresponsive.
authors: Department of Life Sciences, University of Modena and Reggio Emilia, via Amandola 2, Besta building, I-42124 Reggio Emilia, Italy lisa.solieri@unimore.it.
authors: Lisa
authors: L
authors: Solieri
authors: Department of Life Sciences, University of Modena and Reggio Emilia, via Amandola 2, Besta building, I-42124 Reggio Emilia, Italy.
authors: Veronica
authors: V
authors: Vezzani
authors: Department of Life Sciences, University of Modena and Reggio Emilia, via Amandola 2, Besta building, I-42124 Reggio Emilia, Italy.
authors: Stefano
authors: S
authors: Cassanelli
authors: Department of Life Sciences, University of Modena and Reggio Emilia, via Amandola 2, Besta building, I-42124 Reggio Emilia, Italy.
authors: Tikam Chand
authors: TC
authors: Dakal
authors: Department of Physics "G. Galilei", University of Padova, and INFN, via Marzolo 8, I-35131 Padova, Italy CERN, European Organization for Nuclear Research, CH-1211 Geneva 23, Switzerland.
authors: Jacopo
authors: J
authors: Pazzini
authors: Department of Life Sciences, University of Modena and Reggio Emilia, via Amandola 2, Besta building, I-42124 Reggio Emilia, Italy.
authors: Paolo
authors: P
authors: Giudici
mesh_terms: D003470:Culture Media / Q000737:chemistry; D020869:Gene Expression Profiling; D005990:Glycerol / Q000378:metabolism; D008353:Mannitol / Q000378:metabolism; D009997:Osmotic Pressure; D012965:Sodium Chloride / Q000378:metabolism*; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological; D020068:Zygosaccharomyces / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000502:physiology*
chemical_list: D003470:Culture Media; D017923:Sodium-Hydrogen Exchangers; D008353:Mannitol; D012965:Sodium Chloride; D005990:Glycerol
keywords: Na+/H+ antiporters; Zygosaccharomyces yeasts; glycerol; salt; stress response; transcription analysis