[P004] Poster

1:00 PM - 1:50 PM JST(4:00 AM - 4:50 AM UTC)

[P02-264] Comparative genomics and volatile flavor production of Zygosaccharomyces bailii and Zygosaccharomyces rouxii isolated from Korean fermented foods

○Su Jin Yoo¹, Yong Uk Cho¹, Da Min Jeong¹, Yeon Ju Park¹, Che Ok Jeon¹, Seong-Il Eyun¹, Hyun Ah Kang¹ (1. Chung-Ang University (Korea))

Keywords:

Zygosaccharomyces,fermented foods,whole-genome sequencing,comparative genomics,volatile flavors

We comparatively investigated the genomic architectures, stress tolerances, and aroma formation properties of two Zygosaccharomyces yeasts isolated from Korean fermented foods, Zygosaccharomyces bailii CYU23 from a persimmon vinegar, and Zygosaccharomyces rouxii SMY-04 from soy sauce. The ploidy analysis and de novo whole genome sequencing revealed striking differences in their genetic compositions. Z. bailii CYU23 possesses a haploid genome of 11.06 Mb, whereas Z. rouxii SMY-04 is an allodiploid with an 18.2 Mb genome resulting from intraspecies hybridization followed by missing one chromosome. Physiologically, these two strains exhibited divergent adaptations tailored to their distinct isolation environment. Z. bailii CYU23 displayed highly strong resistance to weak organic acids, such as acetic and lactic acids, but was sensitive to osmotic stress. Conversely, Z. rouxii SMY-04 demonstrated robust osmotolerance to high concentrations of salt and sugar. Furthermore, volatile flavor profiling via HS-SPME GC/MS highlighted their unique and complex volatile aroma profiles. Both yeasts produced distinctive arrays of volatile flavor components compared to S. cerevisiae, producing commonly 2-nonanone (methyl heptyl ketone) and 2-nonanol as unique flavor components detected in both Zygosaccharomyces yeasts. Intriguingly, Z. bailii CYU23 displayed more diverse aroma production compared to S. cerevisiae and Z. rouxii SMY-04, particularly higher levels of specific phenethyl esters, including phenethyl butyrate and phenethyl propionate. A set of genes encoding alcohol acyltransferases, containing AATase domain or an α/β hydrolase fold with the Ser−Asp/Glu−His catalytic triad domain, respectively, were identified in the Zygosaccharomyces yeasts, but no homologs of the ATF1 and ATF2 genes. Notably, the heterologous expression of Z. bailii CYU23 EAT1 increased the production of not only ethyl acetate but also other acetate esters and medium-chain fatty acid ethyl esters, such as phenethyl acetate and ethyl octanoate, respectively, indicating its broad substrate specificity. Altogether, our comparative study to elucidate the genome-to-phenotype relationships underlying the stress adaptations and flavor profiles of Zygosaccharomyces yeasts will underscore their promising potential as starter cultures for tailoring complex flavors in various fermented foods.