Cultivo de Chlorella sorokiniana exposta a gases de combustão (CO2, NO2 e SO2) : crescimento, fotossíntese e bioquímica

• Autor(a) principal: Camargo, Eduardo Caffagni de
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFSCAR
• Texto Completo: https://repositorio.ufscar.br/handle/ufscar/7904
• topic: Chlorella sorokiniana; Cimento; Gases de combustão; Fluorescência; Fotossíntese; Viabilidade celular; Proteínas; Carboidratos; Cement flue gases; Fluorescence; Photosynthesis; Cell viability; Proteins; Carbohydrates; CIENCIAS BIOLOGICAS::ECOLOGIA

The cement industry, closely associated with the global warming question, accounts for significant emissions of CO2 and other air pollutants, such as SO2 and NO2 in the atmosphere. In search for ways to mitigate the atmospheric CO2, we performed semicontinuous cultures of Chlorella sorokiniana under phototrophic conditions to test the effect of a flue gas simulation (18% CO2, 9% O2, 300 ppm NO2 and 140 ppm SO2). This was provided once a day in six serial experiments, in which the exposure to the gas was increased through the increase of bubbling time. A constant flow rate allowed us to calculate the total volume of gas introduced into the system each day (0.1, 0.3, 0.8, 1.5, 6 and 48 L). Air-CO2 (18%) was used as control and its bubbling time was pHregulated. Culture medium acidification led to suboptimal growth conditions that affected cell density, photosynthetic activity, cell viability and the biochemical composition of C. sorokiniana. Compared to control, the specific growth rate decreased by 17 and 3,9% in cultures that received 6 and 48 L gas d-1, respectively. The pulseamplitude modulated (PAM) fluorometry was used for culture evaluation. It revealed low maximum quantum yield (ΦM 0.40) and operational quantum yield (Φ'M 0.47) values one day after 48 L gas bubbling. Light saturation curves confirmed the negative effects of long-time gas simulation stress. On the other hand, quenching analysis indicated an increase in photochemical light use and low values of non hotochemical quanching (qN and NPQ). Exposure of the cells to the flue gas simulation resulted in lower cell viability compared to control. Biochemical analysis showed that 6 and 48 L gas d-1 significantly increased protein content by 75% and 154%, respectively; total carbohydrates also increased in the presence of the gas, 148% and 195%, respectively. Despite the physiological changes, C. sorokiniana resisted suboptimal growth conditions imposed by the gas, supporting its vigorous nature and relevance in biotechnological aplications with flue gases.