EQA - Artigos Publicados em Periódicos
URI permanente para esta coleçãohttps://rihomolog.furg.br/handle/1/1611
Navegar
72 resultados
Resultados da Pesquisa
- ItemDevelopment and Characterization of Nanovesicles Containing Phenolic Compounds of Microalgae Spirulina Strain LEB-18 and Chlorella pyrenoidosa(2014) Assis, Letícia Marques de; Machado, Adriana Rodrigues; Motta, Amanda de Souza da; Costa, Jorge Alberto Vieira; Soares, Leonor Almeida de SouzaThe objective of this study was to elaborate liposomes, through the lipid film hydration methodology, to nanoen-capsulate phenolic compounds of Spirulina LEB-18 and Chlorella pyrenoidosa microalgae, and evaluate their physicochemical characteristics and storage stability for 21 days. The total phenolic compounds were evaluated using a calibration curve of gallic acid using methanol and ethanol as extraction solvents. The size and polydis-persity index of nanovesicles were determined by light scattering and the percentage encapsulation efficiency was determined by a centrifugation process. The stability of the liposomes at storage time was measured by zeta potential for 21 days. The methanol extracts from Spirulina had a higher content of phenolic compounds (2.62 mg gallic acid∙g−1 of microalgae) compared to the extracts of Chlorella. However, liposomes with ethanolic ex-tracts of the two algae showed higher encapsulation efficiency. The value was higher (96.40%) for Chlorella. All samples obtained nanometric size, with the highest value obtained for the liposome containing ethanol extract of Chlorella (239 nm) differing significantly (p ≤ 0.05) from the others. The liposomes containing extracts of Spiru-lina were more stable during the 21 days of storage, whereas, those consisting of ethanol extract showed no sig-nificant difference (p ≤ 0.05) throughout this period.
- ItemSolid State Biosurfactant Production in a Fixed-Bed Column Bioreactor(2006) Martins, Vilásia Guimarães; Kalil, Susana Juliano; Bertolin, Telma Elita; Costa, Jorge Alberto VieiraBiosurfactants are surface active substances which reduce interfacial tension and are produced or excreted at the microbial cell surface. We evaluated the biosurfactant production by Aspergillus fumigatus and Phialemonium sp. in solid state processes using fixed-bed column reactors. We evaluated two media, rice husks alone (simple support) and rice husks plus defatted rice bran (complex support), both enriched with either soy oil or diesel oil. The highest water-in-oil emulsifying activity (EAw/o) obtained was 7.36 EU gÐ1 produced by A. fumigatus growing on complex support enriched with soy oil and supplied with air at a rate of 60 mL gÐ1 hÐ1, while Phialemonium sp. had a maximum production of 6.11 EU gÐ1 using the simple support with diesel oil and an aeration rate of 120 mL gÐ1 hÐ1. The highest oilin-water emulsifying activity (EAo/w) was 12.21 EU gÐ1 produced by Phialemonium sp. on the complex support enriched with diesel oil and at an aeration rate of 60 mL gÐ1 hÐ1, while A. fumigatus produced a maximum EAo/w of 10.98 EU gÐ1 when growing on the complex support with no additional carbon source and an aeration rate of 60 mL gÐ1 hÐ1.
- ItemSimultaneous Cultivation of Spirulina platensis and the Toxigenic Cyanobacteria Microcystis aeruginosa(2006) Costa, Jorge Alberto Vieira; Morais, Michele Greque de; Dalcanton, Francieli; Reichert, Carolina da Cruz; Durante, Andrei JoséMangueira Lagoon, located in the extreme south of Brazil, has water with physicochemical characteristics such as alkaline pH and carbonate levels propitious for the growth of the cyanobacterium Spirulina platensis. Previously published studies have shown that Mangueira Lagoon water supplemented with small quantities of carbon and nitrogen is suitable for S. platensis cultivation and can significantly reduce production costs. We studied mixed cultures of Spirulina platensis and the toxic cyanobacterium Microcystis aeruginosa using a 23 factorial design in which the three factors were the initial biomass concentration of S. platensis and M. aeruginosa and the type of culture medium (100% Zarrouk’s medium or 80% Mangueira Lagoon water plus 20% Zarrouk’s medium). The highest S. platensis maximum specific growth rate (μmax) occurred in the culture with the highest M. aeruginosa biomass concentration and when undiluted culture medium was used (μmax = 0.283 dÐ1). The highest M. aeruginosa specific death rate (k) was obtained in the presence of S. platensis (k = 0.555 dÐ1) and was independent of the initial M. aeruginosa biomass concentration and culture medium, demonstrating that S. platensis cultures are not susceptible to contamination by M. aeruginosa. The culture medium had no significant influence (p > 0.05) on S. platensis μmax values, indicating that production costs could be reduced by using a medium consisting of 80% Mangueira Lagoon water plus 20% Zarrouk’s medium.
- ItemRevisão: microalgas: uma fonte alternativa na obtenção de ácidos gordos essenciais(2013) Ferreira, Shana Pires; Soares, Leonor Almeida de Souza; Costa, Jorge Alberto VieiraAs microalgas são micro-organismos fotossintetizantes de grande importância, uma vez que sintetizam biocompostos de alto valor agregado. Os ácidos gordos de microalgas podem ser produzidos tanto de forma autotrófica quanto heterotrófica e sua síntese ocorre no cloroplasto. O objetivo do presente trabalho é realizar uma breve revisão sobre os ácidos gordos poli-insaturados produzidos por microalgas, enfatizando a influência das condições de cultivo das microalgas, síntese e metabolismo para a produção de ácidos gordos. Esta revisão aborda alguns trabalhos desenvolvidos pelo grupo do LEB e, enfoca os seguintes itens: microalgas, conteúdo lipídico das microalgas, síntese e metabolismo de ácidos gordos, influência das condições de cultivo das microalgas na produção de lipídios e perfil de ácidos gordos.
- ItemViabilidade de bactérias láticas em iogurte adicionado de biomassa da microalga Spirulina platensis durante o armazenamento refrigerado(2007) Perez, Karla Joseane; Guarienti, Cíntia; Bertolin, Telma Elita; Costa, Jorge Alberto Vieira; Colla, Luciane MariaA influência de longos períodos de estocagem sobre a contagem de bactérias láticas viáveis tem sido estudada, uma vez que os produtos lácteos fermentados devem possuir um número mínimo de microrganismos, a partir do qual apresentam efeitos benéficos ao consumidor. A adição de biomassa seca da microalga Spirulina platensis pode influenciar beneficamente a sobrevivência das bactérias iniciadoras durante o armazenamento refrigerado, devido à sua composição em proteínas, vitaminas, aminoácidos essenciais, minerais e ácidos graxos essenciais como ácido - linolênico. Objetivou-se avaliar a viabilidade celular das bactérias láticas sob refrigeração em iogurtes preparados com e sem a adição de extrato seco da microalga Spirulina. O iogurte foi elaborado sob condições assépticas e dividido em três amostras: controle, com adição de 0,5 e 1,0 % de biomassa da microalga Spirulina seca. Estas amostras foram armazenadas a 4ºC durante 0, 15 e 30 dias, sendo realizadas contagens de bactérias láticas nestes períodos. A adição de biomassa de Spirulina platensis influenciou positivamente a sobrevivência das bactérias ácido-láticas durante o armazenamento refrigerado, diminuindo a perda de viabilidade durante os 30 dias de armazenamento refrigerado para as amostras adicionadas de 1,0 % de biomassa de Spirulina platensis.
- ItemEvaluation of Filamentous Fungi and Inducers for the Production of Endo-Polygalacturonase by Solid State Fermentation(2002) Dartora, Adriana; Bertolin, Telma Elita; Bilibio, Denise; Silveira, Mauricio Moura da; Costa, Jorge Alberto VieiraFive strains of filamentous fungi (Aspergillus niger strains NRRL 3122 and T0005007-2, Aspergillus oryzae CCT 3940, Aspergillus awamori NRRL 3112 and a Trichoderma sp.) were compared for their capacity to produce endo-polygalacturonase (endo-PG) in solid state fermentation. Maximum pectinolytic activity was reached in 72 h of growth, the best two fungal strains being A. niger T0005007-2 and A. oryzae CCT 3940. Three types of commercial purified pectin and four of unprocessed pectin (tangerine, orange, Tahiti lime and sweet lime rind) were used to assess the effect of pectin on the production of endo-PG by A. niger T0005007-2. Maximum pectinolytic activity was achieved using 6 and 10% (w/w) of purified pectin as inducer. Depending on the origin of the commercial pectin used as inducer, maximum endo-PG levels varied from 223 to 876 units per gram of dry medium (one endo-PG unit (U) was defined as the quantity of enzyme which caused a reduction in viscosity of 50% in a 1% w/v solution of pectin in 30 min), indicating that care should be taken when choosing this component of the medium. When the crude pectins were used as inducers at the same concentration as purified pectin, maximum endo-PG activities were 250Ð300 units/g. However, by increasing the amount of Tahiti lime rind to 50% (w/w) maximum endo-PG was 919 U/g, thus opening up the possibility of a low cost medium for endo-PG production.
- ItemKinetic studies on the biosorption of phenol by nanoparticles from Spirulina sp. LEB 18(2013) Dotto, Guilherme Luiz; Costa, Jorge Alberto Vieira; Pinto, Luiz Antonio de AlmeidaA kinetic study on the biosorption of phenol by nanoparticles from Spirulina sp. LEB 18 was carried out. The Spirulina sp. nanoparticles were prepared and characterized. Kinetic curves of phenol biosorption were obtained in batch system, being verified the effects of initial concentration (50, 150, 250 and 450 mg L 1) and stirring rate (50, 200 and 400 rpm). The models of pseudo-first order, pseudo-second order, Elovich, Bangham, general order and Weber–Morris were used for the kinetic interpretations. Spirulina sp. nanoparticles were stable, monodisperse, spherical with mean diameter of 230 nm. The phenol biosorption was a relatively fast process, being favored at higher values of initial concentration and stirring rate. Pseudo-second order and general order models showed satisfactory fit with the experimental data and the maximum biosorption capacity was around 101 mg g 1. From the Weber– Morris analysis, it was found that external mass transfer and intraparticle diffusion occurred during the phenol biosorption on Spirulina sp. nanoparticles. The externalmass transfer was faster at higher values of initial concentration and stirring rate, and the intraparticle diffusion was favored at high initial concentrations.
- ItemSpirulina platensis Growth in Open Raceway Ponds Using Fresh Water Supplemented with Carbon, Nitrogen and Metal Ions(2003) Costa, Jorge Alberto Vieira; Colla, Luciane Maria; Duarte Filho, Paulo FernandoTo investigate the feasibility of using fresh water from Mangueira Lagoon (Rio Grande do Sul, Brazil) for biomass production in open raceway ponds (0.7 m long, 0.18 m wide, 0.075 m deep) we studied the influence of nutrient addition (carbon as sodium bicarbonate, nitrogen as urea, phosphate, sulfate, ferric iron, magnesium and potassium) on the growth rate of the cyanobacteria Spirulina platensis using a 22 factorial design. In unsupplemented lagoon water production of S. platensis was 0.78 ð 0.01 g/l (dry weight basis) while the addition of 2.88 g/l of sodium bicarbonate (without added urea, phosphate, sulfate or metal ions) resulted in 0.82 ð 0.01 g/l after 400 hours of culture. The further addition of phosphate and metal ions resulted in growth for up to 750 h and a final S. platensis biomass of 1.23 ð 0.04 to 1.34 ð 0.03 g/l.
- ItemProdução de Biomassa de Spirulina sp. LEB 18 com Diferentes Difusores Para Injeção de CO2(2013) Cardias, Bruna Barcelos; Moraes, Luiza; Rosa, Gabriel Martins da; Santos, Lucielen Oliveira dos; Costa, Jorge Alberto VieiraCom a biofixação de CO2 por microalgas, além dos créditos de carbono, podem ser obtidos biomassa, biocombustíveis e outros bioprodutos de interesse comercial. O objetivo deste trabalho foi investigar a influência de diferentes configurações de difusores para a injeção do CO2 no crescimento da microalga Spirulina sp. LEB 18. Os cultivos foram realizados em fotobiorreatores tubulares verticais de 2 L, com fotoperíodo 12 h claro/escuro e 30°C. Na fase clara o ar foi enriquecido com 12% de CO2. A injeção do gás foi realizada com 4 difusores de configurações diferentes, denominados pedra sinterizada, madeira porosa, cortina porosa e anel perfurado.Com exceção da produtividade máxima, as demais respostas de crescimento avaliadas não apresentaram diferença significativa (p>0,05) entre as configurações de difusores empregadas. Assim, foi selecionada a cortina porosa como melhor configuração de difusor a ser empregado no cultivo de Spirulina, pois proporcionou superior produtividade máxima de biomassa (0,13 ± 0,0 g.L-1.d-1).
- ItemEstimating microalgae Synechococcus nidulans daily biomass concentration using neuro-fuzzy network(2013) Furlong, Vitor Badiale; Pereira Filho, Renato Dutra; Margarites, Ana Cláudia Freitas; Goularte, Pâmela Guder; Costa, Jorge Alberto VieiraIn this study, a neuro-fuzzy estimator was developed for the estimation of biomass concentration of the microalgae Synechococcus nidulans from initial batch concentrations, aiming to predict daily productivity. Nine replica experiments were performed. The growth was monitored daily through the culture medium optic density and kept constant up to the end of the exponential phase. The network training followed a full 3³ factorial design, in which the factors were the number of days in the entry vector (3,5 and 7 days), number of clusters (10, 30 and 50 clusters) and internal weight softening parameter (Sigma) (0.30, 0.45 and 0.60). These factors were confronted with the sum of the quadratic error in the validations. The validations had 24 (A) and 18 (B) days of culture growth. The validations demonstrated that in long-term experiments (Validation A) the use of a few clusters and high Sigma is necessary. However, in short-term experiments (Validation B), Sigma did not influence the result. The optimum point occurred within 3 days in the entry vector, 10 clusters and 0.60 Sigma and the mean determination coefficient was 0.95. The neuro-fuzzy estimator proved a credible alternative to predict the microalgae growth.