EFFECT OF CO2 FROM WINE FERMENTATION ON THE KINETIC PARAMETERS OF MICROALGAE GROWTH

GROFF, M. CARLA; GIL ROCIO MARIEL; ALBARETI SANTIAGO; MANZANARES ANA; SÁNCHEZ EMILIA; MARÍA C. FERNÁNDEZ; SCAGLIA, GUSTAVO JUAN EDUARDO

San Juan

Otro; XLI REUNIÓN CIENTÍFICA ANUAL DE LA SOCIEDAD DE BIOLOGÍA DE CUYO; 2023

Sociedad de Biología de Cuyo

The human activity is accelerating the effects of climate change on the planet, due to the alteration of the atmospheric carbon cycle, caused by the large amount of carbon dioxide (CO2) emissions, the primary greenhouse gas. An alternative to reduce CO2 emissions is to transform traditional linear industrial production into sustainable circular production. In San Juan, wine production is one of the main agroindustrial activities, where large volumes of CO2 are generated during the alcoholic fermentation process (by stoichiometry, 1000 l of grape must generate 45,000 l of CO2). Based on this problem, the use of microalgae, photosynthetic microorganisms capable of capturing the CO2 produced in wine fermentation process, is proposed to reduce the carbon footprint of the wineries. The main objective was to evaluate the effect of CO2 generated in wine fermentation on the kinetic parameters of growth of the microalgae Desmodesmus spinosus and Chlorella vulgaris. Wine fermentation was carried out in six 1-liter Erlenmeyer flasks with 750 ml of grape must formulated with rectified must, water, nutrients (yeast extract, thiamine and diammonium phosphate) and tartaric acid (Initial must parameters: ºBx = 21, pH = 3.4, total acidity = 5.5 g/l, easily assimilable nitrogen = 220 mg/l). It was inoculated with commercial yeast (VIN 13), previously activated, at a concentration of 2 x 106 cells/ml in the final must. On the other hand, 6 Erlenmeyer flasks of 250 ml were prepared with 125 ml of Bold Basal Medium (BBM) with microalgae at a concentration of 1 x 106 cells/ml (X0). The strains used were Desmodesmus spinosus (FAUBA-4 strain) and Chlorella vulgaris (Dr. Gagneten, FHUC, UNL). Two of the wine fermentation Erlenmeyers were connected to Erlenmeyers with Desmodesmus spinosus (duplicates D1), another two were connected to Chlorella vulgaris (duplicates C1) and the last two Erlenmeyers were not connected to the microalgae (to quantify the accumulated release of CO2 gravimetrically). In addition, one Erlenmeyer of each microalgae strain was left without CO2 injection as a control (D0 AND C0). The experiment was placed in a room at 25ºC for 20 days, with the microalgae flasks under agitation at 120rpm and 12:12 photoperiod (photosynthetic active radiation, PAR, 200 μmol.m-2.s-1). Microalgae samples were taken every 24h, determining cell concentration with a Neubauer chamber. Matlab R2015a software was used to fit the Logistic Model to the experimental data of cell growth, and to determine the parameters μmax and Xmax in each case. The parameters obtained were: D0: μmax= 0.27 h-1 and Xmax= 5.5 x 107 cells/ml; D1: μmax= 0.41 h-1 and Xmax= 3.6 x 107 cells/ml; C0: μmax= 0.33 h-1 and Xmax= 9.5 x 107 cells/ml; C1: μmax= 0.40 h-1 and Xmax= 7.5 x 107 cells/ml. It can be observed that the main effect of CO2 was evidenced by an increase in the μmax value in both microalgae strains, while the Xmax parameter decreased. In this way, the primary effect of CO2 lies in the acceleration of cell growth of both microalgae strains. As future work, the biomass of microalgae obtained will be characterized in terms of carbohydrate, protein, lipid, chlorophyll and carotenoid content.