Wild Saccharomyces cerevisiae lipid accumulation in lignocellulosic hydrolysate

Microbial oils are currently the most promising feedstock for sustainable biodiesel production. Yeast is attracting considerable attention, but its low productivity on cheap crude substrates, such as lignocellulose-enriched residues, still hinders the industrial application of such oils. The development of robust yeast strains with increased oil yield and resistance to the different inhibitors present in the substrates is therefore one of the most important steps to improve the feasibility of microbial biodiesel.Bioprospecting of wild environments frequently yields microorganisms with high resistance to a wide range of environmental stresses.\ua0 In this project, wild S. cerevisiae strains isolated from spontaneous cacha\ue7a fermentation vessels in Brazil were screened for their potential to produce biodiesel from lignocellulosic residues. The strains that displayed high resistance to common lignocellulosic inhibitors were further assessed for lipid production in wheat straw hydrolysate. The strains’ lipid accumulation profiles were evaluated by measuring growth and fluorescence emission, after addition of lipid-specific fluorescent dye BODIPY. The effects of carbon-to-nitrogen ratio (C/N) and temperature on biomass production and lipid accumulation were also assessed, in order to define the optimal lipid accumulation-inducing conditions for each strain. The best performing strains were further characterized in wheat straw hydrolysate and the lipid profile and accumulation assessed using GC-MS and GC-FID, to identify and quantify the main fatty acids present in the lipids