Project description:Organisms specialized to extreme environments can be the product of millions of years of evolutionary engineering and refinement. The underlying genetics can be quite distinct from those operating at earlier stages of trait innovation. In this work, we have developed the multistress-resistant yeast Kluyveromyces marxianus, which diverged from its closest relative >20 million years ago, as a model for interspecies comparative biology and genomics. In growth assays of the Kluyveromyces genus, we found that K. marxianus exhibited unique tolerance of high heat and a subset of chemical stress conditions. We then generated and analyzed omic profiles from across the genus to find molecular features associated with—and potentially causal for—K. marxianus traits. Expression profiling revealed divergent lipid processing and membrane transport programs in K. marxianus, borne out in changes in lipid utilization in experimental assays. Sequence analyses found robust evidence for expansions in gene families in the K. marxianus genome, most notably among transmembrane transporters and in metabolic enzymes. In molecular-evolution tests, we identified adaptive protein variants throughout the K. marxianus genome, among which plasma membrane transporters were over-represented. These data enable a model of the molecular mechanisms and evolutionary pressures underlying K. marxianus traits, including adaptive changes to transporters, lipid processing, and membrane functions mediating stress resistance.
Project description:Relative quantification of protein abundances of three yeast strains (Saccharomyces cerevisiae CEN.PK113-7D, Kluyveromyces marxianus CBS6556 and Yarrowia lipolytica W29) cultivate in chemostats under different conditions. The conditions for Saccharomyces cerevisiae CEN.PK113-7D are: - Standard condition – 30°C, pH 5.5 - High temperature - 36°C, pH 5.5 - Low pH - 30°C, pH 3.5 - Osmotic stress – 30°C, pH 5.5, 1M KCl The conditions for Kluyveromyces marxianus CBS6556 are: - Standard condition – 30°C, pH 5.5 - High temperature - 40°C, pH 5.5 - Low pH - 30°C, pH 3.5 - Osmotic stress – 30°C, pH 5.5, 0.6 M KCl The conditions for Yarrowia lipolytica W29 are: - Standard condition - 28°C, pH 5.5 - High temperature - 32°C, pH 5.5 - Low pH - 28°C, pH 3.5 This study is part of the OMICS data generation of CHASSY project (European Union’s Horizon 2020 grant agreement No 720824).
Project description:Kluyveromyces marxianus is a non-conventional yeast with outstanding physiological characteristics and a high potential for lignocellulosic ethanol production. However, achieving high ethanol produc-tivities implies overcoming several biotechnological challenges as the cellular inhibition caused by the inhibitors present in the medium. In this work, the adaptation of K. marxianus SLP1 to increase the tolerance to a mix of inhibitory compounds was carried out using the adaptive laboratory evolution (ALE) strategy. As a result of the ALE adaptation process, an improved K. marxianus strain (P8) was obtained after 8 serial passes. The fermentative and physiological parameters evidenced a better response of the P8 strain against the synergistic effect of multiple inhibitors. The P8 strain reduced the lag phase from 12 to 4 h, increasing 40% the biomass and improving 16-fold the volumetric eth-anol productivity. To test the transcriptional dynamics for the adaptation process, we performed a differential gene expression analysis in control conditions; the results showed that the basal gene expression in P8 changes, suggesting the biological capability of K. marxianus to activate the ad-aptative prediction mechanism. This study demonstrates the rapid adaptability of K. marxianus SLP1 to stressful environments, making this yeast a promising candidate to produce lignocellulosic ethanol.
Project description:We have studied Schizosaccharomyces pombe, Saccharomyces cerevisiae, Scheffersomyces (Pichia) stipites, and Kluyveromyces marxianus yeast using the modified IBAQ label-free method with the spiked universal protein standard (UPS2). Each species had been prepared in 3 culturing replicates, and the similarity of the replicates was assessed using the TMT relative quantification methodology.