GENOME-BASED APPROACH FOR SPECIES DELINEATION IN THE GENUS HANSENIASPORA

CHRIS TODD HITTINGER; NEZA CADEZ; DIEGO LIBKIND; NICOLAS BELLORA

Bariloche

Congreso; International Specialized Symposium on Yeasts 34 (ISSY34); 2018

Species of the genus Hanseniaspora are mostly part of fermentative yeast communitieson various fruits and with an ecological advantage of rapid growth they can predominatefruit surface microbiota. Since the introduction of DNA sequence analysis for species delineation the number of newly described Hanseniaspora species has increased fromseven to eighteen, a similar trend as observed for other yeast genera. Among the newlydescribed species are those which exhibit very small divergences in D1/D2 and ITSregions although protein-coding genes and DNA homology values indicated significant genetic discontinuities between species. With the introduction of whole genome sequencing, the genetically distinct species can be delineated using different algorithmsfor determining level of similarities between genomes, such as alignment-free distancemeasure (Kr) or Genome-to-Genome Distance Calculator. In general these analyses giveresults which are in agreement with DNA-DNA reassociation values. Additionally, fromthe genomic information the evolutionary adaptation to specific habitats of the novelyeast species was predicted. In the case of two novel Hanseniaspora species isolatedfrom Cyttaria stromata as part of a fermenting microbiota, we found that the SSU1-likegene encoding a sulfite efflux pump, was present only in few closely related species suggesting that this gene might be one factor for diversification of the novel species.We also searched the genomes of the novel species for candidate genes underlying the physiological traits used for traditional identification. As species of Hanseniaspora canassimilate only a limited number of carbon sources, they also mostly lack homologs ofthe genes required for their utilization.