-NH 4 NO 3 simultaneously provides a readily assimilable nitrogen source (ammonia) and a reserve of nitrogen (nitrate), allowing for an increase in Arthrospira platensis biomass production while reducing the cost of the cultivation medium. In this study, a 2 2 plus star central composite experimental design combined with response surface methodology was employed to analyze the influence of light intensity (I) and the total amount of added NH 4 NO 3 (M t ) on a bench-scale tubular photobioreactor for fed-batch cultures. The maximum cell concentration (X m ), cell productivity (P X ) and biomass yield on nitrogen (Y X/N ) were evaluated, as were the protein and lipid contents. Under optimized conditions (I = 148 µmol·photons·m -2 ·s -1 and M t = 9.7 mM NH 4 NO 3 ), X m = 4710 ±34.4 mg·L -1 , P X = 478.9 ±3.8 mg·L -1 ·d -1 and Y X/N = 15.87 ±0.13 mg·mg -1 were obtained. The best conditions for protein content in the biomass (63.2%) were not the same as those that maximized cell growth (I = 180 µmol·photons·m -2 ·s -1 and M t = 22.5 mM NH 4 NO 3 ). Based on these results, it is possible to conclude that ammonium nitrate is an interesting alternate nitrogen source for the cultivation of A. platensis in a fed-batch process and could be used for other photosynthetic microorganisms.
Arthrospira platensis is widely cultivated in open ponds for industrial purposes. However, high‐protein A. platensis biomass produced in photobioreactors (PBRs) is recommended for pharmaceutical and cosmetic formulations. A. platensis was cultivated in a 3.5 L tubular airlift PBR using both sodium nitrate and urea as nitrogen sources. Sodium nitrate was added from the start of the cultivation using a batch process. Urea was supplied daily at exponentially increasing feeding rate using a fed‐batch process. The simultaneous optimization of the independent variables, namely, total quantity of sodium nitrate (mT1) and total quantity of urea (mT2), led to an optimal condition of mT1 = 15.0 mmol/L and mT2 = 7.5 mmol/L. Maximum biomass concentration (5183 ± 94 mg/L) corresponding to the highest biomass productivity (683 ± 13 mg/L/day) was obtained under such condition. The addition protocol of both nitrogen sources resulted in high productivities of protein (6.2 ± 0.4 mg/L/day) as well as chlorophyll‐a (372.2 ± 7.7 mg/L/day). Such innovative process could be applied in the large‐scale production of A. platensis using tubular PBR for novel applications.
, pela oportunidade e confiança. Pelo conhecimento, apoio, amizade, conselho e sua disposição em sempre ajudar. Aos Professores do Departamento Bioquímico-Farmacêutica pelos ensinamentos passados e pelo suporte no desenvolvimento do trabalho. Ao Iván Alejandro e a Ana Lúcia pela ajuda técnica que me deram ao longo de todos esses anos e principalmente pela amizade, que ultrapassou todas bancadas de laboratório. À todos os meus companheiros de laboratório: Marcello Bresaola, Juliana Tonini, Allan Eiji, Eleane Cezare, João Vitor Molino, Fabíola Ornellas e Maíra Bueno pela paciência, pelo conhecimento, pela prontificação em ajudar e pelas risadas do cotidiano. Àqueles que me deram o primeiro suporte e me despertaram o interesse no campo da pesquisa: Marcelo Matsudo, Mayla Rodrigues, Lívia Ferreira e Raquel Bezerra. Ao Departamento Bioquímico-Farmacêutica e à todos os funcionários, que sempre estiveram prontos a ajudar. À Milza e Fátima, pelos mimos. À Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) pela concessão da bolsa de Mestrado. À todos aqueles que contribuíram para transformar esse trabalho em realidade. Palavras-chave: processo de separação por membranas; Arthrospira platensis; microfiltração; reaproveitamento de meio. ABSTRACT JESUS, C. K. C. Reuse of Arthrospira platensis culture medium treated by microfiltration and ultrafiltration process. 2016. 102 p. Master Dissertation-Faculty of Pharmaceutical Sciences, University of São Paulo, Brazil. Photosynthetic microorganisms, including here the genus Arthrospira, have been produced worldwide in large scale, in a market which generates more than $ 1 billion a year. The industrial production uses huge volume of water with high salinity to produce thousands of tons of microalgal biomass. It is increasing the use of membrane separation process in water treatment, proving to be a technique that generates high quality water, compact and easy both installation and automation. In this study, it was evaluated this technology for the recycling of the culture medium to produce photosynthetic microorganisms, aiming to contribute to the sustainability of this production process. The effluent from Arthrospira platensis culture originating from batch process in laboratory-scale open raceway tanks was treated by tangential flow filtration with microfiltration (MF) (membrane pore size of 0.65 µm and 0.22 µm) and ultrafiltration (UF) (molecular weight cutoff of 5,000 Da), using transmembrane pressure (TMP) from 22.5 up to 90 kPa. MF processes led to average reductions of 53,9±1.3% and 93.1±1.1% of natural organic matter (NOM) and pigments in the exhausted media, respectively. With the use of UF process, whose media were pre-treated by MF (0.22 µm and 22.5 kPa), the average NOM and pigments reductions were 57.2±0.5% and 94.0±0.8%, respectively. The MF process with TMP of 22.5 kPa led to maximum cell concentrations (X m) equivalent to those obtained with the new medium. The use of membrane of 0.65 µm under TMP of 22.5 kPa led to an average loss of 2.9%, 22.7% a...
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