New Saccharomyces cerevisiae-Kluyveromyces marxianus fusant shows enhanced alcoholic fermentation performance

Kluyveromyces marxianus has a promising enological potential because of strong extracellular pectinase activity and the copious production of specific higher alcohols and esters. However, K. marxianus is unable to complete alcoholic fermentation on its own. For this reason it is only used in co- or sequential fermentation in conjunction with Saccharomyces spp. Here we applied the protoplast fusion technique to two commercial Saccharomyces cerevisiae strains (Lalvin EC1118^® and Lalvin QA23^®) and K. marxianus isolate IWBT Y885, to obtain fusants that possess pre-selected, enologically relevant features of K. marxianus, but with improved fermentation performance. After an extensive selection process, performed using non-auxotrophic markers, we identified one fusant, BF2020, that shows enhanced fermentation performance compared to the parental strain K. marxianus Y885, but that still exhibits strong pectinase activity and may be suitable for industrial production. The genome of the selected hybrid was further investigated and characterized by RAPD-PCR analysis and whole genome sequencing.