Investigation of acute toxicity, accumulation, and depuration of ZnO nanoparticles in Daphnia magna.

Size is a key factor controlling the rate of dissolution of nanoparticles, such property can be explored for producing controlled release fertilizers. Hence, one can expect the increasing discharge of nanoparticles closer to water streams in the near future. In this study, we employed the model fresh water organism Daphnia magna to investigate the uptake, acute toxicity and depuration of ZnO nanoparticles. The present study shows that the median lethal concentration (LC50) depended on particle size and the presence of surfactant. The LC50 for positive control ZnSO4 (2.15 mg L-1), 20 nm ZnO (1.68 mg L-1), and 40 nm ZnO (1.71 mg L-1) were statistically the same. However, the addition of surfactant increased the LC50 of 40 nm and 60 nm to 2.93 and 3.24 mg L-1, respectively. The 300 nm ZnO was the least toxic nanoparticle presenting LC50 of 6.35 mg L-1. X-ray fluorescence chemical imaging revealed that Zn accumulated along the digestive system regardless the particle size. Finally, contrary to what have been reported by several papers, the present study did not detect any depuration of ZnO nanoparticles in the next 24 h past the exposure assays. Thus, the ability of organisms to expel ingested nanomaterials might be dependent on specific physical-chemical features of such nanomaterials.

Degradation of textile dyes by cyanobacteria.

Dyes are recalcitrant compounds that resist conventional biological treatments. The degradation of three textile dyes (Indigo, RBBR and Sulphur Black), and the dye-containing liquid effluent and solid waste from the Municipal Treatment Station, Americana, São Paulo, Brazil, by the cyanobacteria Anabaena flos-aquae UTCC64, Phormidium autumnale UTEX1580 and Synechococcus sp. PCC7942 was evaluated. The dye degradation efficiency of the cyanobacteria was compared with anaerobic and anaerobic-aerobic systems in terms of discolouration and toxicity evaluations. The discoloration was evaluated by absorption spectroscopy. Toxicity was measured using the organisms Hydra attenuata, the alga Selenastrum capricornutum and lettuce seeds. The three cyanobacteria showed the potential to remediate textile effluent by removing the colour and reducing the toxicity. However, the growth of cyanobacteria on sludge was slow and discoloration was not efficient. The cyanobacteria P. autumnale UTEX1580 was the only strain that completely degraded the indigo dye. An evaluation of the mutagenicity potential was performed by use of the micronucleus assay using Allium sp. No mutagenicity was observed after the treatment. Two metabolites were produced during the degradation, anthranilic acid and isatin, but toxicity did not increase after the treatment. The cyanobacteria showed the ability to degrade the dyes present in a textile effluent; therefore, they can be used in a tertiary treatment of effluents with recalcitrant compounds.

Degradation of textile dyes by cyanobacteria

Abstract Dyes are recalcitrant compounds that resist conventional biological treatments. The degradation of three textile dyes (Indigo, RBBR and Sulphur Black), and the dye-containing liquid effluent and solid waste from the Municipal Treatment Station, Americana, São Paulo, Brazil, by the cyanobacteria Anabaena flos-aquae UTCC64, Phormidium autumnale UTEX1580 and Synechococcus sp. PCC7942 was evaluated. The dye degradation efficiency of the cyanobacteria was compared with anaerobic and anaerobic-aerobic systems in terms of discolouration and toxicity evaluations. The discoloration was evaluated by absorption spectroscopy. Toxicity was measured using the organisms Hydra attenuata, the alga Selenastrum capricornutum and lettuce seeds. The three cyanobacteria showed the potential to remediate textile effluent by removing the colour and reducing the toxicity. However, the growth of cyanobacteria on sludge was slow and discoloration was not efficient. The cyanobacteria P. autumnale UTEX1580 was the only strain that completely degraded the indigo dye. An evaluation of the mutagenicity potential was performed by use of the micronucleus assay using Allium sp. No mutagenicity was observed after the treatment. Two metabolites were produced during the degradation, anthranilic acid and isatin, but toxicity did not increase after the treatment. The cyanobacteria showed the ability to degrade the dyes present in a textile effluent; therefore, they can be used in a tertiary treatment of effluents with recalcitrant compounds.

Optimization of lipids production by Cryptococcus laurentii 11 using cheese whey with molasses.

This study aimed the optimization of culture condition and composition for production of Cryptococcus laurentii 11 biomass and lipids in cheese whey medium supplemented with sugarcane molasses. The optimization of pH, fermentation time, and molasses concentration according to a full factorial statistical experimental design was followed by a Plackett-Burman experimental design, which was used to determine whether the supplementation of the culture medium by yeast extract and inorganic salts could provide a further enhancement of lipids production. The following conditions and composition of the culture medium were found to optimize biomass and lipids production: 360 h fermentation, 6.5 pH and supplementation of (g L(-1)): 50 molasses, 0.5 yeast extract, 4 KH2PO4, 1 Na2HPO4, 0.75 MgSO4 · 7H2O and 0.002 ZnSO4 · H2O. Additional supplementation with inorganic salts and yeast extract was essential to optimize the production, in terms of product concentration and productivity, of neutral lipids by C. laurentii 11. Under this optimized condition, the production of total lipids increased by 133% in relation to control experiment (from 1.27 to 2.96 g L(-1)). The total lipids indicated a predominant (86%) presence of neutral lipids with high content of 16- and 18-carbon-chain saturated and monosaturated fatty acids. This class of lipids is considered especially suitable for the production of biodiesel.

Optimization of lipids production by Cryptococcus laurentii 11 using cheese whey with molasses

This study aimed the optimization of culture condition and composition for production of Cryptococcus laurentii 11 biomass and lipids in cheese whey medium supplemented with sugarcane molasses. The optimization of pH, fermentation time, and molasses concentration according to a full factorial statistical experimental design was followed by a Plackett-Burman experimental design, which was used to determine whether the supplementation of the culture medium by yeast extract and inorganic salts could provide a further enhancement of lipids production. The following conditions and composition of the culture medium were found to optimize biomass and lipids production: 360 h fermentation, 6.5 pH and supplementation of (g L-1): 50 molasses, 0.5 yeast extract, 4 KH2PO4, 1 Na2HPO4, 0.75 MgSO4•7H2O and 0.002 ZnSO4•H2O. Additional supplementation with inorganic salts and yeast extract was essential to optimize the production, in terms of product concentration and productivity, of neutral lipids by C. laurentii 11. Under this optimized condition, the production of total lipids increased by 133% in relation to control experiment (from 1.27 to 2.96 g L-1). The total lipids indicated a predominant (86%) presence of neutral lipids with high content of 16- and 18- carbon-chain saturated and monosaturated fatty acids. This class of lipids is considered especially suitable for the production of biodiesel.

Comparison of two lipid extraction methods produced by yeast in cheese whey

This work aimed to evaluate nine strains of yeast, previously identified as good producers of lipids in honey medium, for selecting the most suitable strain for the production of lipids in cheese whey medium and compared two well known extraction methods of lipids from the culture medium. The highest yield of total lipids was 1.27 g.L-1 produced by Cryptococcus laurentii 11. A comparison was made between the two culture media: cheese whey and liquid YEPG, and two lipid extraction methods: Bligh and Dyer and Folch et al. for C. laurentii. The experiments were performed with 2² full factorial design using two factors and two levels. Lipid content was higher in cheese whey and there was no difference in the extraction methods statistically. The method of Bligh and Dyer was used in preference to Folch et al. as it resulted in larger mean of total lipids.

Enzymatic hydrolysis of sugarcane bagasse pretreated with acid or alkali

The aim of this study was to evaluate the performance of enzymatic hydrolysis of acid or alkali pretreated sugarcane bagasse for the production of fermentable sugars. The first step consisted of selection of commercial enzymes presenting the highest cellulolytic activities. After selection of four enzymes: HPL, CL, P1 and P4, their performances were tested in the bagasse pretreated with acid and alkali. The sugar content of the hydrolysates was analyzed by anion exchange liquid chromatography. Data showed that the joint action of 0.5 percent acid pretreatment, 121ºC, 30 minutes and enzyme CL provides the best results, 67.25 g of hexose and 148.13g of pentose per kg of dry bagasse.

Use of vinasse and sugarcane bagasse for the production of enzymes by lignocellulolytic fungi

In this present work, three strains of Pleurotus and Trichoderma reesei were cultivated in media with pre-treated bagasse and vinasse. Cellulolytic and lignolytic activities and biomass production were analyzed. The treatment of the bagasse with 2 percent H2O2 + 1.5 percent NaOH + autoclave resulted in a greater fiber breakage increasing the cellulose level up to 1.2 times and decreasing 8.5 times the hemicellulose content. This treatment also resulted in a high lignolytic activity for all cultures utilized. T. reesei produced laccase, peroxidase and manganese-peroxidase in all the treatments, having its manganese-peroxidase activity raging from 1.9 to 4.8 times higher than the basidiomycetes.

Recentemente o uso de material lignocelulolítico tem mostrado um importante avanço na produção de biocombustíveis. O bagaço e a vinhaça são resíduos oriundos do processamento da cana de açúcar e contem um alto teor de carbono, que geralmente é usado na co-geração de energia e ração animal. Três linhagens de Pleurotus e um ascomiceto, Trichoderma reesei, foram cultivados em bagaço pré-tratado e vinhaça. As atividades lignolíticas e celulolíticas foram analisadas, tanto quanto a produção de biomassa. Foi observado que o tratamento no bagaço com 2 por cento H2O2 + 1.5 por cento NaOH + autoclave resultou numa maior quebra da fibra, aumentando o teor de celulose em 1.2 vezes mais e diminuiu em 8.5 vezes o conteúdo de hemicelulose. Este tratamento também resultou numa alta atividade lignolítica pelos fungos utilizados. O ascomiceto T. reesei produziu lacase, peroxidase e manganês-peroxidase em todos os tratamentos, tendo uma atividade de manganês-peroxidase variando entre 1.9 a 4.8 vezes mais que nos basidiomicetos.

Isolation of diuron-degrading bacteria from treated soil

A degradação do herbicida diuron foi estudada em solo com e sem histórico de aplicação obtendo-se aproximadamente degradação sete vezes maior no solo com histórico de aplicação, após 64 dias de incubação. Houve um aumento no número de bactérias no solo com histórico de aplicação de 3.3 x 10 elevado a 6 potência para 1.9 x 10 elevado a 8 potência UFC. g-1 solo. Não houve aumento na biomassa após a incubação, porém foi encontrado significante resíduo de 14C-diuron na biomassa. Um consórcio de três bactérias foi isolado, Acinetobacter johnsonii e duas espécies de Bacillus sp., em meio contendo diuron como única fonte de carbono. Somente A. johnsonnii foi capaz de crescer sozinha em meio contendo diuron como única fonte de carbono.

Biodegradação de Glifosato em dois solos brasileiros / Biodegradation of Glyphosate in two brazilian soils

Avaliou-se a biodegradação de Glifosato em amostras de dois solos brasileiros, ambos com e sem histórico de uso prévio do herbicida. Aplicou-se o Glifosato em 75 g de cada amostra de solo (tres repetições) na dosagem recomendada para condição de campo (2,16 kg i.a/ha). A biodegradação foi avaliada monitorando-se a liberação de CO2 pelos microorganismos no período de 32 dias. Durante esse período foram quantificados os resíduos de Glifosato e seu principal metabólito por meio de extração, seguida de análise por Cromatografia a Líquido de Alta Eficiência. Os resultados mostraram que o Glifosato foi degradado pelos microorganismos do solo, com formação de seu metabólito ácido aminometilfosfônico (AMPA). A degradação mostrou-se ligeiramente superior em Argissolo que em Latossolo

Lixiviaçäo do inseticida C-endosulfan em solos do Estado de Säo Paulo / Percolation of insecticides C-endosulfan in soils of the Parana State, Brazil

A lixiviaçäo do C-Endosulfan foi estudada em tres solos do Estado de Säo Paulo, com diferentes propriedades físico-químicas. Foram montadas tres colunas de lixiviaçäo para cada tipo de solo, com 28 cm de altura, 5 cm de diâmetro e fluxo de água de 0,14 mL/min, simulando 48 horas de precipitaçäo com intensidade de 200 mm de chuva. Coletou-se o lixiviado a cada 12 horas, determinando-se seu volume e radioatividade. Cerca de 78 por cento da radioatividade aplicada permaneceu nos primeiros 2 cm para os tres solos. O solo com menor teor de matéria orgânica e argila (Areia Quartzosa - AQ) foi o que teve maior quantidade do inseticida lixiviado. O solo com maior teor de matéria orgânica apresentou menor teor de inseticida na soluçäo do solo para ser lixiviado. A quantidade acumulada de Endosulfan encontrada nos lixiviados, após 48 horas, foi relativamente baixa, tendo o solo AQ apresentado 0,17 por cento do total aplicado