Molecular and physiological characteristics of a grape yeast strain containing atypical genetic material M.S. Cappello a, ⁎, P. Poltronieri a , G. Blaiotta b , G. Zacheo a a Department of Agrofood, Institute of Sciences of Food Productions, CNR, Prov.le Lecce-Monteroni, km. 7, 73100 Lecce, Italy b Department of Food Science, University of Napoli “Federico II”, Via Università 100, 80055 Portici (Naples), Italy abstract article info Article history: Received 26 April 2010 Received in revised form 30 July 2010 Accepted 13 August 2010 Keywords: Grape yeast Primitivo wine Saccharomyces cerevisiae The knowledge about wine yeasts remains largely dominated by the extensive studies on Saccharomyces (S.) cerevisiae. Molecular methods, allowing discrimination of both species and strains in winemaking, can profitably be applied for characterization of the microflora occurring in winemaking and for monitoring the fermentation process. Recently, some novel yeast isolates have been described as hybrid between S. cerevisiae and Saccharomyces species, leaving the Saccharomyces strains containing non-Saccharomyces hybrids essentially unexplored. In this study, we have analyzed a yeast strain isolated from “Primitivo” grape (http://www.ispa.cnr.it/index.php?page=collezioni&lang=en accession number 12998) and we found that, in addition to the S. cerevisiae genome, it has acquired genetic material from a non-Saccharomyces species. The study was focused on the analysis of chromosomal and mitochondrial gene sequences (ITS and 26S rRNA, SSU and COXII, ACTIN-1 and TEF), 2D-PAGE mitochondrial proteins, and spore viability. The results allowed us to formulate the hypothesis that in the MSH199 isolate a DNA containing an rDNA sequence from Hanseniaspora vineae, a non-Saccharomyces yeast, was incorporated through homologous recombination in the grape environment where yeast species are propagated. Moreover, physiological characterization showed that the MSH199 isolate possesses high technological quality traits (fermentation performance) and glycerol production, resistance to ethanol, SO 2 and temperature) useful for industrial application. © 2010 Elsevier B.V. All rights reserved. 1. Introduction The fermentation of grape juice in the winemaking process is traditionally carried out by indigenous natural yeast flora associated with grapes and winemaking environment. The composition of yeast flora is an important determinant of the quality and the sensory characteristic of the wines. Environmental conditions (sugar concen- tration, increasing alcohol concentration, acidity, increasing synthesis of glycerol, presence of sulphites, anaerobiosis, and progressive depletion of essential nutrients, such as nitrogen, vitamins, and lipids) as well as selection by man for optimal winemaking traits (fermentation performance, alcohol tolerance, and flavour determi- nants) have generated hundred of strains that are required for wine industry applications. Due to the importance of yeast biodiversity to the wine industry, the understanding the mechanisms that participate to the evolution- ary processes that generated the wine yeast strains and the identification of the strains contributing to their oenological proper- ties remain the main challenge. Natural occurring hybridization between Saccharomyces strains has been described by different authors (Hall et al., 2005; Le Jeune et al., 2006). Numerous industrial strains (starters) developed from natural isolates have proved to be interspecies hybrids and similar hybrids have also been detected in natural wine fermentation in various wine-growing regions (Bradbury et al., 2006). Recent analyses have shown that yeast hybrids may be more abundant in both natural and industrial environments than previously thought. Indeed, almost 10% of Saccharomyces strains, previously classified as Saccharomyces sensu stricto, seem to be hybrids between different species (Bradbury et al., 2006; Liti and Louis, 2005). Double and triple hybrids of S. cerevisiae with S. uvarum, S. kudriavzevii, or both were recently identified in yeast populations isolated from grape and cider fermentations. Other examples of S. cerevisiae strains containing DNA from S. mikatae and of the presence of some S. cerevisiae genes in the genomes of S. paradoxus strains were described (Liti et al., 2005). These species were found in the same localities in nature (Sniegowski et al., 2002) and therefore they had the opportunity to cross exchange part of their genetic material generating rare viable gametes (Liti et al., 2006). Due to the coexistence of different yeast species in the same habitat (Sniegowski et al., 2002), the isolation of interspecific hybrids (de Barros Lopes et al., 2002; Liti et al., 2005 b) and interbreeding could have been possible in the wild (Hall et al., 2005; Liti et al., 2006). It appears that favourable combinations of positive properties, International Journal of Food Microbiology 144 (2010) 72–80 ⁎ Corresponding author. Tel.: + 39 0832 422607; fax: + 39 0832 422620. E-mail address: maristella.cappello@ispa.cnr.it (M.S. Cappello). 0168-1605/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.ijfoodmicro.2010.08.013 Contents lists available at ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro