A Method to Discriminate Between the Candida stellata and Saccharomyces cerevisiae in Mixed Fermentation on WLD and Lysine Agar Media

  • S. Di Maio Istituto Regionale della Vite e del Vino (IRVV), Regione Siciliana, Via Libertà 66, 90143 Palermo, Italy
  • G. Polizzotto Istituto Regionale della Vite e del Vino (IRVV), Regione Siciliana, Via Libertà 66, 90143 Palermo, Italy Dipartimento di Ingegneria e Tecnologie Agro-Forestali - Sezione Industrie - Università degli Studi di Palermo, Viale Scienze n.11, 90128 Palermo, Italy
  • D. Planeta Dipartimento di Ingegneria e Tecnologie Agro-Forestali - Sezione Industrie - Università degli Studi di Palermo, Viale Scienze n.11, 90128 Palermo, Italy
  • D. Oliva Istituto Regionale della Vite e del Vino (IRVV), Regione Siciliana, Via Libertà 66, 90143 Palermo, Italy

Abstract

This paper presents a simple method to distinguish between Candida stellata and Saccharomyces cerevisiae
yeasts during microbiological analyses. The method is based on differential yeast growth on a medium
containing cycloheximide and a medium containing lysine as only nitrogen source (lysine agar). The
cycloheximide resistance of 45 yeast strains belonging to Candida stellata, Hanseniaspora uvarum, Hanseniaspora
guilliermondii, Metschnikowia pulcherrima, Torulaspora delbrueckii, Zygosaccharomyces bailii, Kluyveromyces
thermotolerans and Zygoascus hellenicus, and 14 strains of Saccharomyces cerevisiae and Saccharomyces
bayanus on WL nutrient agar, was assayed. Cycloheximide resistance is characteristic of the species H. uvarum,
H. guilliermondii and Z. hellenicus, while for the other yeasts it depends on the strain and the concentration
of cycloheximide used. Two mg/L of cycloheximide allows selective counting of a strain of C. stellata (Cs3)
compared to one of the sensitive S. cerevisiae strain (NDA21). Similar results can be obtained on lysine agar,
but counts are reliable only with the additional spreading of a monolayer of Saccharomyces cells. The different
cycloheximide resistance of C. stellata and S. cerevisiae can be used in the microbiological analysis of mixed
cultures to monitor the individual growth of the two yeast species. This method can be applied to the study
of mixed fermentations with other non-Saccharomyces species. The modified use of lysine agar is useful to a
certain extent in the distinction of multistarter yeasts from the indigenous yeasts.

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Published
2016-12-07
Section
Articles