Proposal of Zygosaccharomyces parabailii sp. nov. and Zygosaccharomyces pseudobailii sp. nov., novel species closely related to Zygosaccharomyces bailii

Abstract

Proposal of INTRODUCTIONZygosaccharomyces bailii is a widely distributed yeast species that is often associated with food spoilage, particularly of acidified, preserved foods containing high concentrations of fermentable sugars (Thomas & Davenport, 1985;Cole & Keenan, 1987;Makdesi & Beuchat, 1996;James & Stratford, 2011). The yeast has been proposed as a new host for several biotechnological processes (e.g. Branduardi et al., 2004) due to its ability to tolerate such environments at relatively high temperatures, which could improve the efficiency of these processes under restrictive conditions. Moreover, the high growth rate of Z. bailii and its high biomass yield make this yeast particularly attractive for heterologous protein and metabolite production (e.g. Sousa et al., 1996Sousa et al., , 1998.Despite their well-known role in food/beverage spoilage, accurate identification of Z. bailii and related yeasts to the species level using conventional taxonomic tests remains problematic. An inability to ferment and assimilate many of the carbon compounds typically used in yeast identification, as well as ambiguous tests results due to strain variability, often hampers identification (James & Stratford, 2011). Furthermore, significant intraspecific variation in internal transcribed spacer (ITS) sequences was also reported among some strains of the species (James et al., 1996), which may cause difficulties for the use of this barcode region for identifying the species (Schoch et al., 2012). We hypothesized that polyphasic analyses of the yeasts encompassed by Zygosaccharomyces bailii sensu lato may lead to a more accurate understanding of their phylogenetic relationship and taxonomic status. Here we report the molecular, physiological and morphological characterization of these yeasts, and propose two novel species near Z. bailii. METHODSYeast strains and characterization. Strains of Z. bailii sensu lato and related taxa were selected from the ATCC Mycology Collection or were provided by bioMérieux, Inc. (Table 1). Morphological observations and metabolic tests comprising the yeast standard Abbreviations: ITS, internal transcribed spacer; LSU, large subunit; SSU, small subunit.

The Genome Sequence of the Highly Acetic Acid-Tolerant Zygosaccharomyces bailii-Derived Interspecies Hybrid Strain ISA1307, Isolated From a Sparkling Wine Plant

“…Following the analysis of the ISA1307 strain genome sequence described below and given that yeast isolates formerly identified as Z. bailii were recently reclassified in the Z. bailii , Z. parabailii and Z. pseudobailii species, 24 we have examined the taxonomic classification of this strain. The sequences of the house-keeping genes RPB1 , RPB2 , EF1-α and β-tubulin were compared.…”

“…The phylogenetic relationships of a large cohort of isolates first classified as Z. bailii were recently re-examined, and significant differences in their rRNA gene sequences and genome fingerprinting patterns were found, leading to the distribution of these isolates into three species: Z. bailii , Z. parabailii and Z. pseudobailii . 24 Despite the differences registered at the molecular level, the Z. bailii species could not be distinguished from the other two novel species using physiological tests. 24 The occurrence in wines of natural hybrid strains generated by hybridization of different Saccharomyces species is widely described in the literature, 25,26 the lagger brewing yeast Saccharomyces pastorianus being the most paradigmatic example.…”

“…24 Despite the differences registered at the molecular level, the Z. bailii species could not be distinguished from the other two novel species using physiological tests. 24 The occurrence in wines of natural hybrid strains generated by hybridization of different Saccharomyces species is widely described in the literature, 25,26 the lagger brewing yeast Saccharomyces pastorianus being the most paradigmatic example. 27 The occurrence of hybrid strains within the Zygosaccharomyces genus involving, at least, the Z. rouxii , Z. pseudorouxii and Z. mellis species, was also reported.…”

Zygosaccharomyces favi sp. nov., an obligate osmophilic yeast species from bee bread and honey

“…According to the classical guideline provided by Kurtzman and Robnett (1998) this amount of divergence suggests that these five strains are not conspecific with Z. gambellarensis. To place in closer context, D1/D2 sequence divergences among strains of the species pairs selected from the group of Z. bailii and the recently described two closely related yeast species Z. parabailii and Z. pseudobailli (Suh et al 2013) may be as small as 0-1 substitution, and Z. siamensis differs by 3 substitutions from Z. mellis (Saksinchai et al 2012). To further investigate the relationship among the five osmophilic strains recovered during this study and the type strain of Z. gambellarensis, the sequences of the ITS regions and the translation elongation factor-1a (EF-1a) gene of these strains were determined.…”

“…In the last decade several new species were added to the genus; Z. machadoi (Rosa and Lachance 2005), Z. gambellarensis (Torriani et al 2011), Z. siamensis (Saksinchai et al 2012), Z. sapae (Solieri et al 2013), Z. parabailii and Z. pseudobailii (Suh et al 2013), and the current number of the recognised Zygosaccharomyces species has risen to 12. The majority of the newly described Zygosaccharomyces species, Z. machadoi, Z. gambellarensis, Z. siamensis and Z. sapae formed a well-supported clade with Z. rouxii and Z. mellis, either based on the sequences of LSU D1/D2 domains of the rRNA gene alone (Rosa and Lachance 2005;Torriani et al 2011;Saksinchai et al 2012;Solieri et al 2013) or on the combined internal transcribed spacer (ITS) and D1/D2 sequence dataset (Suh et al 2013). Zygosaccharomyces rouxii is among the most xerophilic organisms (Pitt and Hocking 2009 and the references therein), but it also grows in/on culture media with high (a w [ 0.99) water activity.…”