HIGH LIPID PRODUCTION OF YEASTS GROWN ON BREWERY SPENT LIQUIDS

ANSALDI, NAZARENA; DUO SAITO, RUBÍ AZUL; TROCHINE, ANDREA; DE GARCIA, V.

Mendoza

Simposio; LVI Reunión Anual de SAIB; 2020

SAIB-SAMIGE

Oleaginous yeasts can produce more than 20% of their dry weight in lipids (triacylglycerides), when grown at high C/N ratios. Their fatty acid profile is similar to plant oils, and may have uses in sustainable biodiesel production, as well as in animal and human nutrition, among others. The main cost for an economically feasible production of these single cell oils is associated with the culture medium carbon source. In this work, the lipid production ability of 57 yeast strains isolated from Patagonia was evaluated using microbrewery effluents as sole nutrient source (no supplementation). Eight strains were selected based on their high lipid production, evaluated by fluorescence microscopy with nile red, and their ability to lower the sugar content of the effluents. The selected strains were used for biomass and lipid qualitative and quantitative evaluations (gravimetric and GC-MS lipid analyses), after growth in brewery spent liquids (5° Bx boiling remainings), for 120 h at 20°C, 180 rpm. Culture supernatants were evaluated for Chemical Oxygen Demand (COD), Kjeldahl Nitrogen (N), and total Phosphorus (P). All yeast strains (Vishniacozyma victoriae G1A2.3, Solicoccozyma aeria A3-2.12, Tausonia pullulans G4A5.8, Solicoccozyma sp. G4A3.28, Basidiomycete sp. B2-5.2, Vanrija albida VN6.4, Holtermaniella wattica B2-5.3, Basidiomycete sp. BH4-3) showed high biomass production (between 10 and 20 g/L) with Solicoccozyma sp. G4A3.28 showing the highest production. The best volumetric lipid producers were S. aeria A3-2.12 (8,2 g/L), H. wattica B2-5.3 (7,3 g/L), and Basidiomycete sp. B2-5.2 (7.1 g/L); the former showing the highest lipid production in terms of dry biomass (60%). Fatty acid profiles in all strains were dominated by oleic C18:1 (33-7%), linoleic C18:2 (13-27%), palmitic C16:0 (17-24%) and stearic C18:0 (3-10%) acids. As for COD removal, V. victoriae removed 88% of the initial COD followed by T. pullulans (86%). Total N was removed between 57 to 84% (V. albida) and total P from 48 to 98% (Solicocozyma sp.). Based on these results, S. aeria A3-2.12, Basidiomycete sp. B2-5.2 and H. wattica B2-5.3 were selected for optimization assays. Future analyses will include different brewery spent liquids and optimization of culture conditions for maximization of lipid production and COD removal.