Suppressing cyanobacterial dominance by UV-LED TiO2-photocatalysis in a drinking water reservoir: a mesocosm study.

Cyanobacteria and their toxic secondary metabolites present challenges for water treatment globally. In this study we have assessed TiO2 immobilized onto recycled foamed glass beads by a facile calcination method, combined in treatment units with 365 nm UV-LEDs. The treatment system was deployed in mesocosms within a eutrophic Brazilian drinking water reservoir. The treatment units were deployed for 7 days and suppressed cyanobacterial abundance by 85%, while at the same time enhancing other water quality parameters; turbidity and transparency improved by 40 and 81% respectively. Genomic analysis of the microbiota in the treated mesocosms revealed that the composition of the cyanobacterial community was affected and the abundance of Bacteroidetes and Proteobacteria increased during cyanobacterial suppression. The effect of the treatment on zooplankton and other eukaryotes was also monitored. The abundance of zooplankton decreased while Chrysophyte and Alveolata loadings increased. The results of this proof-of-concept study demonstrate the potential for full-scale, in-reservoir application of advanced oxidation processes as complementary water treatment processes

Partial purification of crude lipase extract from Yarrowia lipolytica: Precipitation, aqueous two-phase systems (ATPS), and immobilization methods

Efforts have been concentrated on developing alternative methods of enzyme purification that are less costly and highly efficient. In this work, we evaluated three different methods for lipase purification from Yarrowia lipolytica, such as precipitation using ammonium sulfate, ethanol, or acetone; aqueous two-phase systems (ATPS) based on polyethylene glycol (PEG) and potassium phosphate; and direct immobilization. It was impossible to obtain stable precipitates of the enzyme due to the low concentration of total protein and the presence of biosurfactant produced by the microorganism. Different mixture compositions were selected for the partitioning study. Three ATPS showed selective partitioning of the target enzymes, i.e., lipase and protease migrated to opposite phases. In the ATPS composed of 13 wt% PEG-4000 and 10 wt% salts, it was possible to achieve a purification factor for lipase of 4.2. Purification by immobilization performed by lipase-lipase interactions showed three lipases of distinct sizes in the crude extract. In the immobilization method by hydrophobic supports, phenyl-agarose and butyl‑agarose were more selective in immobilizing than octyl-agarose. In the ion exchange immobilization method, only the lipases identified at 66 kDa and 41 kDa have an attraction for DEAE-agarose (anionic) and sulfopropyl-agarose (cationic) matrices

Suppressing cyanobacterial dominance by UV-LED TiO₂-photocatalysis in a drinking water reservoir:a mesocosm study

Cyanobacteria and their toxic secondary metabolites present challenges for water treatment globally. In this study we have assessed TiO2 immobilized onto recycled foamed glass beads by a facile calcination method, combined in treatment units with 365 nm UV-LEDs. The treatment system was deployed in mesocosms within a eutrophic Brazilian drinking water reservoir. The treatment units were deployed for 7 days and suppressed cyanobacterial abundance by 85% while at the same time enhancing other water quality parameters; turbidity and transparency improved by 40 and 81% respectively. Genomic analysis of the microbiota in the treated mesocosms revealed that the composition of the cyanobacterial community was affected and the abundance of Bacteroidetes and Proteobacteria increased during cyanobacterial suppression. The effect of the treatment on zooplankton and other eukaryotes was also monitored. The abundance of zooplankton decreased while Chrysophyte and Alveolata loadings increased. The results of this proof-of-concept study demonstrate the potential for full-scale, in-reservoir application of advanced oxidation processes as complementary water treatment processes

Larvicidal activity of the water extract of Moringa oleifera seeds against Aedes aegypti and its toxicity upon laboratory animals

In this work, biological effects of the water extract of Moringa oleifera seeds (WEMOS) were assessed on eggs and 3rd instar larvae of Aedes aegypti and on its toxicity upon laboratory animals (Daphnia magna, mice and rats). Crude WEMOS showed a LC50 value of 1260µg/mL, causing 99.2 ± 2.9% larvae mortality within 24 h at 5200µg/mL, though this larvicidal activity has been lost completely at 80ºC/10 min. WEMOS did not demonstrate capacity to prevent egg hatching. After extensive dialyses of the crude WEMOS into watersoluble dialyzable (DF) and nondyalizable (NDF) fractions, only DF maintained its efficacy to kill larvae. Acute toxicity evaluations on daphnids (EC50 of 188.7µg/mL) and mice (LD50 of 446.5 mg/kg body weight) pointed out to low toxicity. Despite the thymus hypertrophy, WEMOS revealed to be harmless in orally and subacutelytreated rats. In conclusion, WEMOS has thermostable bioactive compounds against Ae. aegypti larvae with apparent molecular mass lower than 12 kDa and moderately toxic potential.<br>Neste trabalho, o extrato aquoso das sementes de Moringaoleifera (EASMO) foi avaliado quanto aos seus efeitos biológicos sobre ovos e larvas de Aedes aegypti no 3ºestágio de desenvolvimento e sua toxicidade sobre animais de laboratório(Daphnia magna, camundongos e ratos). O EASMO bruto revelou uma CL50 de 1.260 µg/mL, causando 99, 2 ± 2, 9% de mortalidade em 24 h na concentração de 5.200 µg/mL, embora o mesmo não tenha sido capaz de impedir a eclosão dos ovos. A atividade larvicida extinguiu-se após aquecimento do extrato a 80ºC/10 min. Diálises sucessivas do EASMO bruto resultaram em duas frações solúveis em água (Fração dializável, FD; Fração nãodializável, FND), dentre as quais apenas a FD mostrou ação larvicida. Testes de toxicidade aguda realizadosem dáfnias (CE50 de 188, 7 µg/mL) e camundongos (DL50 de446,5 mg/kg de peso corpóreo) evidenciaram baixa toxicidade. Apesar da hipertrofia tímica, o EASMO mostrou ser atóxicoapós tratamento subagudo via oral em ratos. Conclui-se, portanto, que o EASMO apresenta substâncias com capacida de larvicida contra Ae. aegypti, as quais possuem massa molecular aparente menor que 12 kDa e potencial tóxico moderado