Data supporting the publication: Sedimentation accelerates mixed-substrate conversion during sequential batch cultivation of a co-culture of sugar-specialist yeast strains

All data for the paper: <strong>Sedimentation accelerates mixed-substrate conversion during sequential batch cultivation of a co-culture of sugar-specialist yeast strains </strong>Type of research: Microbiology, PhysiologyMethod of data collection: Fermentation in Bioreactors, molecular biologyAbstract: Current industrial processes for yeast-based conversion of glucose, xylose, and arabinose mixtures in lignocellulosic hydrolysates mostly rely on monocultures of generalist strains that consume the sugars sequentially. Co-cultivation of ‘sugar-specialist’ strains offers potential advantages related to volumetric productivity and genetic stability of pentose-fermenting strains during prolonged operation. However, in these cultures, the slow fermentation of xylose and arabinose strongly affects the time required for complete sugar conversion. This study explores if the overall kinetics of such co-cultures can be improved by selective sedimentation of a slow-fermenting strain in sequential batch fermentations. Deletion of <em>ACE2</em> in a diploid, arabinose-specialist <em>Saccharomyces cerevisiae</em> strain yielded a multicellular, fast-sedimenting phenotype. In monocultures on 20 g∙L^-1 arabinose in anaerobic sequential batch bioreactors with a 30-min biomass settling period between cultivation cycles, the sedimenting strain showed a shorter time for full conversion than its non-sedimenting parental strain (11.5 ± 0.4 h and 16.6 ± 0.4 h, respectively). Co-cultures of a glucose-specialist <em>S. cerevisiae</em> strain with the sedimenting arabinose specialist on a glucose-arabinose mixture (10 g·L^-1 of each sugar) showed a 29% shorter batch time than corresponding co-cultures with the non-sedimenting arabinose-specialist strain (12.6 ± 0.1 h vs. 17.7 ± 0.1 h). Increasing the biomass settling period to 1 h further reduced the batch time to 8.1 ± 0.1 h and resulted in near-simultaneous depletion of both sugars. These results show that, if selective sedimentation of specific slow-fermenting strains can be implemented under relevant process conditions, it has the potential to improve microbial conversion of mixed substrates.<br>Research data contains all batch records, pictures of the engineered strains, as well as sedimentation kinetics. From this, it will be possible to reproduce all figures in the publication (will be included as soon as a DOI is available.)