Non-conventional yeasts as superior production platforms for sustainable fermentation based bio-manufacturing processes

Non-conventional yeasts are an excellent option for a number of different industrial bioprocesses. They possess beneficial natural phenotypes, which translates to several fermentation advantages when compared to traditional hosts, like Saccharomyces cerevisiae. The non-conventional yeasts Yarrowia lipolytica, Trichosporon oleaginosus, Kluyveromyces marxianus, Dekkera bruxellensis, Pichia kudriavzevii, Debaryomyces hansenii and Hansenula polymorpha, are considered desirable industrial hosts due to their natural characteristics, including tolerance to several by-products and inhibitors, thermotolerance, salt resistance or osmo- and xerotolerance. Therefore, they are a great alternative for the industrial production of bioethanol, fine chemicals, lipids and recombinant proteins, among others. In this review, we summarize the best natural characteristics of those seven non-conventional yeasts and their use in industrial biotechnology, as well as the molecular/synthetic biology tools available for their genetic modification. Moreover, possible limitations regarding their performance in industrial fermentations and a list of challenges to overcome in the future are also discussed.