Summary auto-generated
This study describes three new yeast species isolated from soil and partially decayed leaves on Yaku Island and Iriomote Island in Japan. The organisms were identified as Saccharomyces naganishii, Saccharomyces humaticus, and Saccharomyces yakushimaensis based on DNA-DNA hybridization, physiological characteristics, and 18S rDNA gene sequencing. All isolates produced asci with 1-4 globose ascospores and contained Q-6 ubiquinone, supporting classification within Saccharomyces sensu lato. The three species were distinguished by electrophoretic karyotyping patterns and differed substantially from existing Saccharomyces species in DNA sequence similarity (2.4-49.7%). S. naganishii ferments multiple sugars and assimilates specific nitrogen sources; S. humaticus and S. yakushimaensis show more restricted fermentation patterns. Phylogenetic analysis using 18S rDNA sequences confirmed their positions within the Saccharomyces genus and relationships to related ascomycetous genera. Type strains have been deposited in culture collections.
Key findings
- Three novel Saccharomyces species (naganishii, humaticus, yakushimaensis) were isolated from Japanese island soil and leaf samples and characterized using DNA-DNA hybridization, physiological tests, and 18S rDNA sequencing
- Species were distinguished by electrophoretic karyotyping patterns (10-12 chromosomal bands) and showed low DNA similarity (2.4-49.7%) to all existing Saccharomyces species
- S. naganishii ferments glucose, galactose, sucrose, trehalose, and raffinose; S. humaticus and S. yakushimaensis ferment only glucose and galactose
- All three species contain Q-6 ubiquinone, produce persistent asci with 1-4 ascospores, and are homothallic
- Phylogenetic analysis confirmed placement within Saccharomyces sensu lato with distinct evolutionary relationships to Kluyveromyces, Torulaspora, and Zygosaccharomyces
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Abstract
Three new yeast species were isolated from soil and partially decayed leaves in Yaku Island and Iriomote Island in the Nansei Islands of Japan. Based on DNA hybridization and physiological characters, these represent novel taxa. These are designated Saccharomyces naganishii sp. nov. (type strain IFO 10181(T)=CBS 8797(T)), Saccharomyces humaticus sp. nov. (type strain IFO 10673(T)=CBS 8893(T)) and Saccharomyces yakushimaensis sp. nov. (type strain IFO 1889(T)=CBS 8894(T)). The phylogenetic relationships of the three new species with members of other ascomycetous genera (e.g. Kluyveromyces, Saccharomyces, Torulaspora and Zygosaccharomyces) were estimated by 18S rDNA gene sequence analysis.