High-throughput screening of a Debaryomyces hansenii library for potential candidates with improved stress tolerance and wider carbon utilisation capabilities

Industrial biotechnology comprises the manufacturing of bulk chemicals and high-value end-products from renewable feedstocks, thus it presents a valuable aspect in the present transition from traditional-resource demanding manufacturing to sustainable solutions. The non-conventional yeast Debaryomyces hansenii encompasses halotolerant characteristics that ensures its use in industrial applications, and hence, its industrial importance. For this purpose, a comprehensive and holistic understanding of its behaviour and response to abiotic stresses is essential. Through high-throughput screening methods, using advanced robotics and automation devices, the present study enlightens intraspecies behavioural characteristics of novel D. hansenii strains in response to sodium, as well as their ability to tolerate abiotic stress in semi-controlled micro-fermentations and spot-test studies. A significantly improved performance under those abiotic stresses was observed under the presence of 1M NaCl. Moreover, a positive and summative effect on growth was also found in pH 4 and high salt content. Our results align with previous findings suggesting the halophilic (and not just halotolerant) behaviour of D. hansenii , which is now extensive to all the D. hansenii strains included in this study. Strain-specific differential responses to the presence of sodium were also observed, with some strains exerting a more notable induction by the presence of salt than the standard strain (CBS767). Furthermore, our study provides indications of the use of D. hansenii in industrial bioprocesses based on lignocellulosic biomass and non-lignocellulosic feedstocks.