No description available.

The extraction of oil from microalgae was investigated. The study focused on the hydrothermal liquefaction of the microalgae Microcystis aeruginosa, Cyclotella meneghinia and Nitzschia pusilla. M. aeruginosa was collected from the Hartebeespoort dam, while C. meneghinia and N. pusilla were cultured in the laboratory. The experiments were conducted in a high pressure autoclave with an inert atmosphere. Sodium carbonate was studied as a potential catalyst. The hydrothermal liquefaction of M. aeruginosa, C. meneghinia and N. pusilla was carried out at various reaction temperatures and catalyst loads. For the liquefaction of M. aeruginosa the residence times were also varied. The reaction temperatures ranged from 260 to 340 °C, while the catalyst loads varied between 0 and 10 wt% Na2CO3. The residence time was varied between 15 and 45 minutes. The study showed that hydrothermal liquefaction of M. aeruginosa produced a maximum oil yield of 15.60 wt% at 300 °C, whereas the thermochemical liquefaction of C. meneghinia and N. pusilla produced maximum yields of 16.03 wt% and 15.33 wt%, respectively, at 340 °C. The residence time did not influence thermochemical liquefaction of the algae, while an increase in the catalyst load reduced the oil yield. The reaction conditions had no effect on the elemental composition or the calorific value of the thermochemical liquefaction oil. The calorific value of the hydrothermal liquefaction oils ranged from 28.57 to 35.90 MJ.kg -1 . Hydrothermal liquefaction of microalgae produced oil that can be used as substitute for coal in simple gasification processes. The study showed that microalgal blooms, such as the M. aeruginosa blooms of the Hartebeespoort dam, can be used for the extraction of oil through hydrothermal liquefaction. / Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2010.

The extraction of oil from microalgae was investigated. The study focused on the hydrothermal liquefaction of the microalgae Microcystis aeruginosa, Cyclotella meneghinia and Nitzschia pusilla. M. aeruginosa was collected from the Hartebeespoort dam, while C. meneghinia and N. pusilla were cultured in the laboratory. The experiments were conducted in a high pressure autoclave with an inert atmosphere. Sodium carbonate was studied as a potential catalyst. The hydrothermal liquefaction of M. aeruginosa, C. meneghinia and N. pusilla was carried out at various reaction temperatures and catalyst loads. For the liquefaction of M. aeruginosa the residence times were also varied. The reaction temperatures ranged from 260 to 340 °C, while the catalyst loads varied between 0 and 10 wt% Na2CO3. The residence time was varied between 15 and 45 minutes. The study showed that hydrothermal liquefaction of M. aeruginosa produced a maximum oil yield of 15.60 wt% at 300 °C, whereas the thermochemical liquefaction of C. meneghinia and N. pusilla produced maximum yields of 16.03 wt% and 15.33 wt%, respectively, at 340 °C. The residence time did not influence thermochemical liquefaction of the algae, while an increase in the catalyst load reduced the oil yield. The reaction conditions had no effect on the elemental composition or the calorific value of the thermochemical liquefaction oil. The calorific value of the hydrothermal liquefaction oils ranged from 28.57 to 35.90 MJ.kg -1 . Hydrothermal liquefaction of microalgae produced oil that can be used as substitute for coal in simple gasification processes. The study showed that microalgal blooms, such as the M. aeruginosa blooms of the Hartebeespoort dam, can be used for the extraction of oil through hydrothermal liquefaction. / Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2010.

Cyanobacterial secondary metabolites, often identified as toxins such as microcystin, have also demonstrated biological functions including inhibition of bacterial and viral growth. In this study, 10 cyanobacterial strains were isolated from field sites around Adelaide and laboratory cultures and assessed for bioactivity against bacterial, viral and fungal pathogens. A comprehensive literature search identified a number of screening assays employed by research groups to identify cyanobacterial strains with biological activity. Within the review, methods to optimise extraction of the compounds were also noted. Combinations of extraction methods, solvents and assay procedures were investigated to optimise the success of this phase of the study. Bioactivity was confirmed by development of agar disc diffusion and microtitre plate assays to analyse cyanobacterial biomass extracts. Result of the assays indicated a methanolic extract of one species, Microcystis flos-aquae (Wittr Elenkin), inhibited growth of bacterial cells and viral infectivity and was selected for further analysis. The bioactive compound was isolated by HPLC and mass spectrometric analysis. Separation of the bioactive extract into component peaks indicated only one that was likely to represent the metabolite of interest, at a retention time of approximately 18 min. A second profile was constructed of a methanolic extract of the same species in a later growth stage that did not inhibit growth of either the bacterial or viral test organisms. Comparison of the profiles exposed the absence of the peak at 18 min retention time in the second profile. Accumulation of the fraction was conducted using a semi-preparative HPLC column for analysis by mass spectrometry. A sample of the isolated peptide was submitted to Proteomics International, a subsidiary of Murdoch University, WA, for identification and structural characterisation. Proteomics International analysed the data by electronspray ionisation time of flight mass spectrometry (LC/MS/TOF) followed by LC. De novo sequence analysis of the data was carried out using Analyst QS software; however, PI was unable to provide a readily interpretable, continuous amino acid sequence, despite their admission that some gaps in the fragmentation ladder corresponded to known amino acids. Interpretation of the data generated by Proteomics International by a research chemist within the University of Adelaide proposed the following amino acid sequence and subsequent structure for the compound: [Figures omitted] Proposed (a) amino acid sequence and (b) structure for the bioactive compound isolated from non-toxic M. flos-aquae. Comparison of the proposed sequence with those contained in peptide databases was unable to classify the compound (B Neilan, personal communication, April 2008), suggesting the bioactive metabolite is perhaps previously undetected and therefore may be considered a novel compound, or has undergone a modification and is thus a variant of a known compound. Taxonomic classification of the strain used during this study was completed by PCR amplification of 16S ribosomal RNA, using primers from alternative cyanobacterial sources. The sequence was classified in the following taxonomic hierarchy (with 100% assignment detail, for a confidence threshold of 95%): Domain: Bacteria Phylum Cyanobacteria Class Cyanobacteria Family Family 1.1 Genus Microcystis This classification confirms that the species investigated during this research is of the genus Microcystis. Synthesis of cyanobacterial metabolites is generally accepted to be a result of nonribosomal synthetic pathways. The presence of non-ribosomal peptide synthetase and polyketide synthetase genes in Microcystis flos-aquae was confirmed by PCR amplification using degenerate primers from other cyanobacterial sources. Analysis of sequence data identified the presence of an NRPS gene demonstrating significant similarity (98%) to the NRPS cyanopeptolin gene of Microcystis sp. However, the PKS (polyketide) gene identified verified only a 63% similarity to a known sequence, that of the PKS (mcyG) gene of M. aeruginosa PCC 7806 (Koch). Results of the molecular investigation imply this compound may belong within the cyanopeptolin family. Researchers have speculated that the majority of cyanobacteria possess genes for production of toxins, though in many instances the gene cluster may be incomplete or one or more genes may be absent or mutated. The presence of microcystin genes was confirmed by PCR amplification using primers from previously characterised cyanobacterial genes. Analysis of the sequence data identified the presence of several mcy genes generally found in toxic strains of cyanobacteria noted for synthesis of the toxin microcystin. The DNA sequences show significant similarity to the mcyA, mcyC, mcyD and mcyE genes described for Microcystis sp. and Microcystis aeruginosa PCC 7806. However, analysis of the sequence data for the mcyB gene revealed that this gene was not present. Further PCR amplification of the region between mcyA and mcyC using the reverse complements of the original primers indicated that a sequence was present that may have been a truncated variant of mcyB or another gene entirely. Time constraints prohibited submission of this region for sequence analysis. The primary objective of this research project was to screen a field strain of cyanobacteria for synthesis of biologically active secondary metabolites, and to isolate those compounds using a combination of analytical chemistry and molecular biotechnology. This study forms part of a collaborative project between the University of Adelaide, South Australian Research and Development Institute (Aquatic Sciences) and the Environmental Biotechnology Cooperative Research Centre, entitled “P6: Commercial scale integrated biosystems for organic waste and wastewater treatment for the livestock and food processing industries”. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1352988 / Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering, 2009

DINIZ, Francisco Bruno. Dinâmica e produtividade primária da comunidade fitoplanctônica em reservatório do semiárido brasileiro. 2016. 68 f. Dissertação (Mestrado em Ecologia e Recursos Naturais)-Universidade Federal do Ceará, Fortaleza, 2016. / Submitted by Anderson Silva Pereira (anderson.pereiraaa@gmail.com) on 2017-01-18T17:08:51Z No. of bitstreams: 1 2016_dis_fbdiniz.pdf: 944223 bytes, checksum: c35d9b4228fcade8b977d348279403a8 (MD5) / Approved for entry into archive by Jairo Viana (jairo@ufc.br) on 2017-01-19T12:17:59Z (GMT) No. of bitstreams: 1 2016_dis_fbdiniz.pdf: 944223 bytes, checksum: c35d9b4228fcade8b977d348279403a8 (MD5) / Made available in DSpace on 2017-01-19T12:17:59Z (GMT). No. of bitstreams: 1 2016_dis_fbdiniz.pdf: 944223 bytes, checksum: c35d9b4228fcade8b977d348279403a8 (MD5) Previous issue date: 2016 / The semiarid region of Northeast Brazil is characterized by a system of seasonal rains,variable in space and time, prolonged droughts and annual recurrent droughts interannual and high temperatures and almost constant during the year. This natural scenario justifies the natural water scarcity in the region, which depends on the construction of reservoirs as a strategic measure to its socioeconomic development. The semi-arid climatic conditions have influenced the structure and composition of phytoplankton community of the reservoirs and therefore the phytoplankton primary productivity. Thus, the objective of this research was to identify and evaluate the seasonal dynamics and primary productivity of phytoplankton community Pereira reservoir Miranda, municipality of Pentecoste, Ceará, and link them to climate variables, hydrological and limnological. Water samples were collected monthly in 2015 to determine physical variables (temperature, water clarity and turbidity), chemical (dissolved oxygen, conductivity, pH, total phosphorus, orthophosphate, ammonia, nitrite, nitrate and silica) and biological ( chlorophyll a and primary productivity), and phytoplankton collections for identification, counting and calculating the Shannon diversity index - Wiener. The data were statistically analyzed by analysis of variance (ANOVA) for primary productivity and multivariate principal component analysis (PCA) to order the physical and chemical variables and express the relationships between them. As a result, there were changes in limnological characteristics with prolonged drought. There was no significant difference (p> 0.05) in primary productivity during the months studied. However, there was a higher primary productivity in the rainy season. Thirty have been identified and a phytoplankton species, especially Microcystis sp. (Unitary), with dominance in the rainy season, and plenty of Aphanocapsa elachista in the dry season. The Shannon diversity index - Wiener was down for both periods, with plenty of few species, and increase from the end of the rainy season. Thus, it can be inferred that the dry scenario observed during the study interfered with limnologic conditions and phytoplankton diversity in Pereira de Miranda reservoir, i.e., changes in physical and chemical factors of water, enhanced by prolonged drought affected adversely the primary productivity of Pereira de Miranda reservoir. / A região semiárida do Nordeste brasileiro é caracterizada por regime de chuvas sazonais, variável no espaço e no tempo, estiagens anuais prolongadas e secas interanuais recorrentes e por temperaturas elevadas e praticamente constantes durante o ano. Este cenário natural justifica a escassez hídrica natural da região, que depende da construção de reservatórios como medida estratégica para o seu desenvolvimento socioeconômico. As características climáticas do semiárido tem influênciado a estrutura e na composição das comunidades fitoplânctônicas dos reservatórios e, consequentemente, a produtividade primária fitoplanctônica. Diante disso, o objetivo desta pesquisa foi identificar e avaliar a dinâmica sazonal e a produtividade primária da comunidade de fitoplâncton do reservatório Pereira de Miranda, município de Pentecoste, Ceará, e associá-las às variáveis climáticas, hidrológicas e limnológicas. Amostras de água foram coletadas mensalmente em 2015 para determinação de variáveis físicas (temperatura, transparência da água e turbidez), químicas (oxigênio dissolvido, condutividade elétrica, pH, fósforo total, ortofosfato, nitrogênio amoniacal, nitrito, nitrato e sílica) e biológicas (clorofila a e produtividade primária), além de coletas de fitoplâncton para identificação, contagem e cálculo do índice de diversidade de Shannon - Wiener. Os dados foram tratados estatisticamente por análise de variância (ANOVA) para produtividade primária e análise multivariada em componentes principais (ACP) para ordenar as variáveis físicas e químicas e expressar as relações entre elas. Como resultado, observaram-se alterações nas variáveis limnológicas com o prolongamento da estiagem. Não foi observada diferença significativa (p > 0,05) na produtividade primária durante os meses estudados. No entanto, observou-se maior produtividade primária no período chuvoso. Foram identificadas trinta e uma espécies fitoplanctônicas, com destaque para Microcystis sp. (unitária), com dominância no período chuvoso, e abundância da Aphanocapsa elachista no período seco. O índice de diversidade de Shannon – Wiener foi baixo para ambos os períodos, com abundância de poucas espécies, e aumento a partir do final do período chuvoso. Assim, pode-se inferir que o cenário de seca observado durante a pesquisa interferiu nas condições limnológicas e na diversidade de fitoplâncton no reservatório Pereira de Miranda, isto é, as mudanças nos fatores físicos e químicos da água, intensificados pela seca prolongada, afetaram negativamente a produtividade primária do reservatório Pereira de Miranda

Blooms of cyanobacteria have increased in occurrence in the past three decades and have been reported to cause severe problems for animals and humans, leading to death in extreme instances. The majority of poisonings that have taken place have been attributed to a hepatotoxin produced by the species Microcystis aeruginosa, namely microcystin. The appearance of a cyanobacterial bloom does not give any indication as to its toxicity and therefore, it is imperative that simple, yet sensitive, bioassays are developed to overcome this problem. This study was undertaken to evaluate the effects of microcystin-LR on the liver of Xenopus laevis both in vitro and in vivo. This animal provides an opportunity to study the long-term hepatotoxic effects of the toxin compared to in vitro studies performed with mice and rats. The use of the liver slice model system as a potential bioassay to study the effects of microcystin-LR on Xenopus laevis liver was evaluated. Liver slices were cultured in RPMI- 1640 culture medium for periods ranging from 30 hours to 10 days and the liver slices were exposed to toxin concentrations ranging from 1nM to 500nM. The use of frog liver slices to study the longer-term effects of low-dose exposure to microcystin-LR was evaluated by observing the ultrastructural changes within hepatocytes using transmission electron microscopy, the release of the enzymes alanine aminotransferase and lactate dehydrogenase into the surrounding culture medium, as well as using a 3-[4,5-dimethylthiazol-2yl]-2,5- diphenyl tetrazolium bromide assay to determine the viability of the liver slices in culture. The amount of lipid peroxidation in the liver slices after exposure to microcystin-LR was assessed using the Thiobarbituric Acid Test. Results showed the frog liver slice culture system to be an inadequate method to evaluate the hepatotoxic effects of microcystin-LR. An in vivo assessment of the effects of microcystin-LR on Xenopus laevis was carried out using a total of 9 frogs (3 groups of 3 frogs). Frogs received a single intraperitoneal dose of 120mg/kg of microcystin-LR and were sacrificed at 8 and 24 hours post exposure. Microcystin-LR caused no significant change in serum lactate dehydrogenase levels, hepatosomatic index (liver weight as a percentage body weight), glutathione peroxidase activity, glycogen or lipid peroxidation. There was, however, an increase in glutathione sii transferase activity in the liver. The presence of the toxin in the liver was confirmed by immunohistochemistry. This study suggests that Xenopus laevis has, in some way, adapted to detoxifying aquatic toxins in the environment.

This study reports the findings on the effect of nitrates and phosphates on the biomass and toxin production of various strains of the unicellular non-nitrogen fixing cyanobacterium, Microcystis aeruginosa. The occurrence of blooms of Microcystis aeruginosa and microcystin in freshwater impoundments across the globe has been on the increase lately due to increased levels of eutrophication, resulting in human and animal deaths and illness, as well as drinking and recreational water foulment. A range of environmental factors have been shown to effect growth and microcystin production. Existing literature however is somewhat contradictory as to the effects of these physical and chemical factors on toxin production. Therefore Microcystis aeruginosa strains were cultured under batch and continuous conditions to determine the effect of nitrate and phosphate concentrations and ratios on biomass and toxin production. Cultures were analysed with regards to internal nutrient stores, biomass production, nutrient depletion, photosynthetic efficiency and microcystin production. Results showed that microcystin production correlated to growth rate, photosynthetic efficiency and internal nitrogen stores and that an optimal N:P ratio was associated with microcystin levels, growth rate and photosynthetic efficiency. Results therefore led to the conclusion that the nitrogen, carbon, and phosphate balance within the cell is closely associated with microcystin production. Whether or not microcystin is produced to maintain this balance or produced as a function of this balance remains to be determined.

No description available.

Reservoirs are the main drinking water sources in Taiwan. However, about half of 23 reservoirs suffer the eutrophication problems based on the calculated Carlson¡¦s TSI indexes for them. Thus, the reservoir water is seriously polluted. Chen-Ching Lake Reservoir, Fengshan Reservoir, and A-Kong-Tien Reservoir are three major reservoirs that supply water for the domestic, industrial, and agricultural uses in the Kaohsiung area. Due to the long-term sediment deposition at A-Kong-Tien Reservoir, a sediment dredge system is under construction at this reservoir. Thus, only Chen-Ching Lake Reservoir and Fengshan Reservoir play the most important roles in water supply at this moment. However, both Chen-Ching Lake Reservoir and Fengshan Reservoir are in the list of the most eutrophized reservoirs. There are several ways to evaluate the status of eutrophication of reservoirs. The single-index method and multi-variable modeling method are two of the most commonly methods for water quality analysis and eutrophication evaluation for the reservoirs in Taiwan. Based on the analytical results from previous studies, eutrophication results in the fast growing of seaweeds and they spread and cover the whole water bodies, which is called algal bloom. The type of seaweed causing eutrophication in Taiwan reservoirs are mainly Cyanobacteria, especially the commonly found Microcystis. They can not only cause some foul smells but release toxins into the water bodies. That endangers the safety of drinking water and affects the normal water usage. To prevent eutrophication, the nutrients loadings outside and inside of the reservoir areas must be reduced and controlled, which can effectively prohibit the growth of seaweeds. An air-pumping system can also be built for the same purpose. Regular water quality inspection should be carried out to monitor the fluctuation of water quality.

Thesis (M.S.)--University of North Carolina at Wilmington, 2003. / Includes bibliographical references (leaves : 63-66).