Les microalgues rouges de l’espèce Rhodella violacea produisent un exopolysaccharide soluble dans le milieu de culture. Au cours de ce travail, les conditions optimales de production ont été déterminées en étudiant l’activité photosynthétique et le milieu de culture des microalgues. La croissance cellulaire et la production d’EPS de R. violacea sont optimales avec un milieu de culture f/2 modifié, supplémenté en azote et en phosphore. L’irradiance optimale est de 420 μmol de photons.m-2.s-1, sous une température de 24°C avec un pH de 8,3. La culture de la microalgue en photobioréacteur de 5 L a permis la production optimale de 0,5 g.L-1 de polymère. Le polysaccharide produit est un protéoglycane de type xylane sulfaté et de haute masse molaire (1,2 106 g.mol-1), contenant également du rhamnose, du glucose, de l’arabinose, du galactose et de l’acide glucuronique. L’effet antiparasitaire des polymères de microalgues et de macroalgues a été testé sur des microsporidies, in vitro avec des fibroblastes de prépuce humain infestés par Encephalitozoon cuniculi et in vivo contre la nosémose des abeilles causée par Nosema ceranae. L’exopolymère de R. violacea empêche la croissance des microsporidies in vitro et in vivo, et conduit à une diminution de la mortalité des abeilles. D’autres molécules testées ont également une action antiparasitaire, les EPS de Porphyridium purpureum et marinum, et des carraghénanes sulfatés permettent également de diminuer la croissance des microsporidies et la mortalité des abeilles. / Red microalgae from Rhodella violacea species product a soluble exopolysaccharide release in the media. In this study, optimal culture conditions for exopolysaccharide production were investigated, following photosynthesis activity and culture conditions. This study allowed us to determinate R. violacea optimal media for growth and exopolysaccharide production, which is f/2 media supplemented in nitrogen and phosphorus. Optimal physicochemical parameters are an irradiance of 420 μmol photons.m-2.s-1, a temperature of 24°C, and a pH of 8.3. Photobioreactor of 5 L used to cultivate R. violacea in optimal conditions, gave 0.5 g.L-1 of EPS. Structural analysis of the EPS revealed the production of a proteoglycan, principally composed by xylose, sulfated and with a high molecular mass (1.2 106 g.mol-1). The polymer is complex, as it contains different monosaccharide: rhamnose, galactose, arabinose and glucuronic acid. The antiparasitic effect of polymers from microalgae, and macroalgae were investigated on microsporidia, in vitro against Encephalitozoon cuniculi using Human foreskin fibroblasts, and in vivo against Nosema ceranae using bees. Exopolysaccharide from R. violacea decreases microsporidia growth in vivo and in vitro. In addition, in vivo the polymer allows decrease in bees’ mortality. Polysaccharide from others origins also have antiparasitic effet, such as exopolymer from Porphyridium purpureum and marinum, and sulphated carragheenans which reduce microsporidia growth, and decrease bees’ mortality.

Submitted by Izabel Franco (izabel-franco@ufscar.br) on 2016-09-12T14:31:07Z No. of bitstreams: 1 DissCC.pdf: 2450373 bytes, checksum: 8cbe8a964a77ba28b6fc5019b478228a (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-12T18:57:19Z (GMT) No. of bitstreams: 1 DissCC.pdf: 2450373 bytes, checksum: 8cbe8a964a77ba28b6fc5019b478228a (MD5) / Approved for entry into archive by Marina Freitas (marinapf@ufscar.br) on 2016-09-12T18:57:30Z (GMT) No. of bitstreams: 1 DissCC.pdf: 2450373 bytes, checksum: 8cbe8a964a77ba28b6fc5019b478228a (MD5) / Made available in DSpace on 2016-09-12T18:57:48Z (GMT). No. of bitstreams: 1 DissCC.pdf: 2450373 bytes, checksum: 8cbe8a964a77ba28b6fc5019b478228a (MD5) Previous issue date: 2015-10-23 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Vinasse is a waste of sugarcane industry and, due to the presence of organic matter and mineral nutrients, it has been used for the irrigation of the sugarcane crops. However, its composition limits such application due to soil salinization. The anaerobic fermentation of vinasse generates biogas that is used as energy source in the sugarcane industry itself. The fermented vinasse results in biodigested vinasse. The development of techniques for residue use can contribute to cleaner production systems. In this research, we evaluated treated conventional and biodigested vinasses for the growth of Chlorella vulgaris. The treatment consisted of filtering the vinasses through smectite clay and activated carbon, or centrifugation. Concentrations of 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100% of treated vinasses were tested. Cell density, absorbance at 570 nm, pH and electrolyte conductivity were quantified daily in a six day experiment. Based in cell density, specific growth rates were calculated. Growth rates higher than the controls were obtained in 60% conventional filtered vinasse and 10% conventional centrifuged one, as well as in 80% biodigested filtered vinasse and 20% biodigested centrifuged vinasse. In general, the filtered vinasse was superior in relation to the centrifuged one regarding higher residue concentration that supported microalgae growth. After microalgae acclimation we evaluated the photosynthetic performance of C. vulgaris in the best vinasses conditions and the biochemical composition of the biomass present in the vinasse, which besides the microalgae contained other microorganisms, such as bacteria and fungi, since it was not sterilized. Specific growth rate for C. vulgaris in 60% filtered conventional vinasse was 1.6 d-1 and 1.5 d-1 in the 80% filtered biodigested vinasse, representing increases of up to 84 x in cell density compared to the initial. In the LC Oligo control the growth rate was ~ 0.9 d-1 and in the BG11 it was 1,1 d-1. Although the better C. vulgaris growth in the treated vinasses, photosynthetic efficiency and its related parameters were better in the control than in the vinasses. These results together with those of chlorophyll a concentration suggest that the microalgae have possibly used a mixotrophic metabolism while in the vinasses. We observed higher biomass accumulation in the vinasses than in the controls. A reduction of total dissolved organic carbon and dissolved mineral elements up to 50%, as well as bacteria and fungi, were detected in the vinasse after microalgae growth. This study is a contribution to the knowledge of microalgae physiology in a residue and to the development of cleaner ethanol production system. / A vinhaça é um resíduo da indústria sucroalcooleira que, devido à presença de matéria orgânica e nutrientes minerais, tem sido utilizada para fertirrigação das próprias culturas de cana-deaçúcar. Porém, a composição desse resíduo limita sua aplicação no solo, pois pode levá-lo à salinização. A fermentação anaeróbia da vinhaça gera biogás que é usado como fonte de energia para a própria usina. Essa fermentação resulta na vinhaça biodigerida. Técnicas que permitam utilizar as vinhaças, convencionais ou biodigeridas, contribuem para um sistema de produção mais limpo e rentável. Propusemos nesta pesquisa, avaliar o uso de vinhaça tratada. Para tanto usamos vinhaça convencional e biodigerida, filtradas em argila esmectita e carvão ativado, ou centrifugadas. Nelas cultivamos Chlorella vulgaris (BEYERINCK, 1890). As vinhaças tratadas foram testadas em concentrações de 10, 20, 30, 40, 50, 60, 70, 80, 90 e 100%. Avaliamos diariamente a densidade celular, absorbância em 570 nm, pH e condutividade eletrolítica ao longo de seis dias. Com os resultados de densidade celular, calculamos as taxas de crescimento para cada tratamento. Os melhores crescimentos se deram em vinhaça convencional filtrada 60% e centrifugada 10% e, em vinhaça biodigerida filtrada 80% e centrifugada 20%. Em geral, as vinhaças filtradas suportaram o crescimento das microalgas em concentrações superiores em relação às centrifugadas. A produção de biomassa foi maior nos filtrados em comparação com centrifugados. Após aclimatação da microalga em vinhaça avaliaram-se os parâmetros fotossintéticos e bioquímicos da biomassa produzida em vinhaça biodigerida filtrada 80% e em vinhaça convencional centrifugada 60%. Taxas de crescimento específicas de C. vulgaris de 1,6 d-1 foram obtidas na vinhaça filtrada convencional 60% e 1,5 d-1 na biodigerida filtrada 80%, representando aumentos de até 84 x nas densidades celulares em relação às iniciais. No controle LC Oligo esse valor foi de 0,9 d-1 e no BG11 foi de 1,1 d-1. Apesar do melhor crescimento algal nas vinhaças, a eficiência fotossintética e os parâmetros relacionados foram melhores no controle do que nas vinhaças. Esses resultados sugerem que a microalga na vinhaça possa ter utilizado a via mixotrófica como fonte de carbono. Observou-se que houve maior acúmulo de biomassa nos cultivos em vinhaça do que nos controles. Houve redução do conteúdo de carbono orgânico total dissolvido e de elementos minerais na vinhaça em até 50%, bem como da contaminação por fungos e bactérias ao final dos cultivos. Este estudo é uma contribuição para o conhecimento da fisiologia de microalgas em resíduos e para o desenvolvimento de uma produção de etanol mais sustentável.