Seleção e otimização de meios de cultura para o cultivo de microalgas

• Autor(a) principal: Euclides, Thais Moraes de
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2554
• topic: Meio de cultura; Scenedesmus sp.; Chorella sp.; Otimização; Culture medium; Scenedesmus sp .; Chorella sp .; Optimization; CNPQ::CIENCIAS BIOLOGICAS::BOTANICA

Biodiesel produced from microalgae is a promising alternative to fossil fuels. However, its production is not economically viable due to the high costs in various stages of production. To overcome this problem, during the cultivation, increasing the lipid content and reducing the cost of culture medium is a good alternative. The objective of this study was to select a nutritionally adequate medium to two species of microalgae, with different additions of CO2 and then optimize this medium in order to obtain greater production of biomass and lipids. In a first step, six synthetic culture medium, reported in the literature, were chosen (BG11, MDM, MBM, BBM, MC and Illman), and determined which medium provided the lowest cost production of lipids. For the culture medium, the Illman medium provided the highest production of biomass, 1.81 g L-1 and 1.4 g L-1 for Chlorella sp. and Scenedesmus sp., respectively. The cultures that received higher concentrations of CO2 produced, in general, higher amount of dry matter. For Chlorella sp., there was no increase in lipid and carbohydrates content in response to supplementation of CO2, but for Scenedesmus sp., the mediums MBM and MC responded to supplementation with 5%, resulting in an increase of lipids and reduction of carbohydrates content. When comparing the costs of the culture medium, MBM medium showed a lower average cost for the production of lipids. In the next stage, the optimization, the goal was to manipulate the composition of the medium MBM, through changes in the levels of N, P, K and Mg, in order to increase the production of biomass and lipid content of Scenedesmus sp. BR003. Using the Rotational Central Composite Design, the variables tested were dry biomass and lipid content per dry weight (%). The results indicated that in the range of concentrations used, the nitrogen promoted great influence in cell growth, and an increase in the concentration of this nutrient increases the production of ash-free biomass in 27 %. The total amount of lipids increased by 48 % when compared to the highest and lowest concentrations of N and P. It was observed that it is more advantageous to have low concentrations of N and P in the culture medium than a large number of cells. Since this large number of cells did not generate higher amount of lipid per liter of culture medium. Although the amounts of lipids obtained are still not enough to make feasible the production of biodiesel from this microalgae, manipulating the nutrients of the culture medium was found to be a great tool for the increase of production of lipids.