Arthospira (Spirulina) platensis (Nordstedt) Gomont was autotrophically cultivated for biomass production in repeated fed-batch process using urea as nitrogen source, with the aim of making large-scale production easier, increasing cell productivity and then reducing the production costs. It was investigated the influence or the ratio of renewed volume to total volume (R), the Urea feeding time (t(f)) and the number of successive repealed fed-batch cycles on the maximum cell concentration (X(m)), cell productivity (P(x)), nitrogen-to-cell conversion yield (Y(x/n)), maximum specific growth rate (mu(m)) and protein content of, dry biomass. The experimental results demonstrated chat R=0.80 and t(f) = 6d were the best cultivation conditions, being able to simultaneously ensure, throughout the three fed-batch cycles, the highest average values of three of the five responses (X(m) = 2101 +/- 113 mg L(-1), P(x) = 219 +/- 13 mg L(-1) d(-1) and Y(x/n) = 10.3 +/- 0.8,g g(-1)). (C) 2008 Elsevier B.V. All rights reserved.; FAPESP, Brazil[04/04004-1]; FAPESP, Brazil[04/04012-4]
The microalgae biomass production from swine wastewater is a possible solution for the environmental impact generated by wastewater discharge into water sources. The biomass can be added to fish feed, which can be used in the formulation of meat products. This work addresses the adaptation of the microalgae Spirulina platensis (Arthrospira platensis) in swine wastewater and the study of the best dilution of the wastewater for maximum biomass production and for removal of Chemical Oxygen Demand (COD), ammonia and phosphorous to the microalgae. The cultivation of Spirulina platensis, strain Paracas presented maximum cellular concentrations and maximum specific growth rates in the wastewater concentration of 5.0 and 8.5%. The highest COD removals occurred with 26.5 and 30.0% of wastewater in the medium. The maximum removal of total phosphorous (41.6%), was with 8.5% of wastewater, which is related to the microalgae growth. The results of Spirulina culture in the swine wastewater demonstrated the possibility of using these microalgae for the COD and phosphorous removal and for biomass production.
The main aim of this work was to investigate the effects of temperature and nitrogen concentration on the antioxidant potential of extracts from Spirulina (Arthospira) platensis biomass. S. platensis biomass obtained at 35ºC and with 1.875 g.L-1 or 2.5 g.L-1 of sodium nitrate in the culture medium presented higher concentrations of phenolic compounds. The antioxidant potential of methanol extracts of biomass on the enzymatic browning caused by peroxidase were 29 and 35%, respectively, being the reduction related to the amount of phenolic compounds present in this extract.
In order to assess the potential of Spirulina (Arthospira) platensis as a source of abundant, thermostable nitrate assimilatory enzymes, the specific activities and thermal tolerance of nitrate reductase (NR), nitrite reductase (NiR) and glutamine synthetase (GS) were compared with those of rice in crude extracts in vitro. The results show that Spirulina enzymes have relatively higher thermotolerance. When the extracts were pre-exposed to 80 °C for 1 hr, Spirulina enzymes retained higher activities by 3.4, 1.7 and 3.7 fold, respectively than corresponding enzymes in rice. This property was not due to salts and other small proteins/molecules, as their removal by gel filtration (G-25) did not affect their thermotolerance.
Este estudo teve por objetivo descrever a variação quali-quantitativa da microflora planctônica e bentônica em escala espaço-temporal, e identificar quais os principais fatores relacionados com as variações observadas no lado nordeste da ilha de Fernando de Noronha (PE). As coletas foram realizadas em maré de sizígia em três pontos fixos, durante o período chuvoso (março, maio e julho/2010) e de estiagem (setembro e novembro/2010; fevereiro/2011). Foram identificados 95 taxa para o fitoplâncton e 52 taxa para o microfitobentos. Apesar das diatomáceas terem sido o grupo com maior riqueza, as cianobactérias e dinoflagelados também estiveram representados com a dominância de Oscillatoria sp, Lepocinclis salina, Prorocentrum lima e pequenas diatomáceas (Bacillariophyceae) no fitoplâncton, e Aphanothece sp, Arthospira spirulinoides, Synechococcus sp, Bellerochea malleus e Navicula spp e cianobactérias (Chrorococcales) no microfitobentos. A diversidade específica na área é baixa a muito baixa, com aumento período chuvoso no P1 (fitoplâncton) e período de estiagem no P2 (microfitobentos). A estrutura das microalgas é afetada pelas variáveis ambientais (pluviometria, teores de salinidade, oxigênio dissolvido, taxa de saturação de oxigênio...