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published_or_final_version / abstract / Biological Sciences / Doctoral / Doctor of Philosophy

The purpose of this study is evaluating a new water treatment technology; electrochemical technique and see if the technique is an alternative for municipal wastewater treatment. The aim of the project was also to test the electroflotation by purification of phosphorus from synthetic wastewater and separation of green algae from the culture medium so the technology can be evaluated. To answer the purpose, two different experiments were made at laboratory. In the first experiment, wastewater was purified from phosphorus with electroflotation. In the second experiment, green algae were separated with the same technology, but with different machine. The results of the study show that the electrochemical technology is a good technique to separate green algae from the culture medium. In the tests the removal efficiency was over 90 %. Results from the phosphorus purification did not go so well, because sources of error in the system. To summarize the results of the project the electrochemical technology is a good alternative to other wastewater treatments because it’s more environmental friendly and easy to operate.

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Twenty-two different unialgal clonal isolates have been obtained at random for experimental purposes over a period of about one year. Also, during this period, at least 12 other species or strains have been isolated into unialgal cultures which had not yet been identified and/or significantly cleared of heterotrophic contaminants.

This thesis reports the effect of the non-toxic cyanobacterium Oscillatoria agardhii CYA29 and its spent medium on the cell-bound toxin levels in Microcystis aeruginosa PCC7820 and Nodularia sp. PCC7804. Microcystin levels were elevated when O. agardhii or its spent medium were added to cultures of M. aeruginosa PCC7820. This effect was also observed for two nodularin variants in Nodularia PCC7804. However, growth of M. aeruginosa in its own spent medium did not lead to elevated microcystin levels. Some Gram-negative bacteria use quorum sensing, the determination of population density by pheromones, to regulate the expression of traits in a density dependent manner. The presence of the bacterial pheromones, acyl-homoserine lactones (AHLs), was investigated in cyanobacteria and a simple and fast synthesis for AHLs employed. No AHLs have been found in the cyanobacterial species tested, neither by Chromobacterium violaceum CV026 nor by Escherichia coli HB101 pUCD607 bioassay. No changes in dry weight or microcystin concentration were observed in M. aeruginosa PCC7820 grown in the presence of the AHL N-hexanoyl-DL-homoserine lactone. The activity of the spent medium of O. agardhii CYA29 was retained when it was heated up to 100°C for 20 min, frozen or freeze-dried. Molecular weight cut-off filtration showed the active compound to be less than 1 kD in size. The active component could not be extracted by dichloromethane or methanol, and activity was lost upon acidification. A small peptide of five amino acid moieties was isolated from an active fraction of the spent medium, four of which have been identified by 1H NMR to be serine, glycine, alanine, and the modified serine(thiazole). To my knowledge this is the first report of serine(thiazole) in natural products and the first thiazole containing peptide from O. agardhii.

Orientador: Ciro Cesar Zanini Branco / Banca: Carlos Eduardo de Mattos Bicudo / Banca: Orlando Necchi Junior / Banca: Ina de Souza Nogueira / Banca: Celia Leite Sant'Anna / Resumo: Algas verdes são organismos presentes em todo o mundo, ocorrendo em uma grande amplitude de condições ecológicas. Em ambientes lóticos, elas são importantes tanto para a produção primária quanto para a criação e manutenção de habitats para outros organismos. Neste contexto, o presente estudo teve como objetivo abordar a taxonomia, distribuição ambiental e considerações biogeográficas das algas verdes macroscópicas de ambientes lóticos localizados em Unidades de Conservação (UC) na região Sul do Brasil. Para tanto, foram amostradas 10 UC's dos quatro principais biomas desta região, totalizando 105 riachos. Na abordagem taxonômica foram tratadas 16 espécies pertencentes às ordens Chaetophorales, Cladophorales, Klebsormidiales, Microsporales e Ulotrichales, além de três espécies de algas verdes coloniais. Uma espécie do gênero Basicladia foi considerada como novo registro para a ciência e Cladophora sterrocladia foi registrada pela primeira vez no Brasil. Na abordagem teórica foram discutidos os aspectos reprodutivos das famílias Oedogoniaceae e Zygnemataceae e a sua implicação em estudos taxonômicos e ecológicos. Uma hipótese relacionada à poliploidia foi sugerida para explicar a baixa frequência de ocorrência de espécimes portadores de estruturas reprodutivas em ambientes lóticos. A partir dos materiais destas duas famílias encontrados nos riachos do Sul do Brasil foi conduzida uma separação em 12 morfotipos baseados essencialmente no diâmetro celular. Estes morfotipos foram testados quanto a sua relação com as variáveis ambientais. Por fim, considerando o aspecto ecológico foi abordada a distribuição ambiental das algas verdes macroscópicas de riachos nos principais biomas da região Sul do Brasil, levando em consideração os padrões de riqueza, abundância e composição de espécies e a sua relação com a distância geográfica e as ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Green algae are organisms found throughout the world, occurring in a wide range of ecological conditions. In lotic environments, green algae are important both for primary production and for the creation and maintaining of habitats for other organisms. In this context, this study aimed to addressing the taxonomy, ecological distribution and biogeographical considerations of lotic macroscopic green algae in conservation units (UC) in Southern Brazil. For this purpose, 10 UC's in four principal biomes of this region were sampled, amounting 105 streams. In the taxonomic approach were treated 16 species belonging to the orders Chaetophorales, Cladophorales, Klebsormidiales, Microsporales and Ulotrichales, and three species of colonial green algae. One species of the genus Basicladia was considered as a new record to the science and Cladophora sterrocladia was first recorded in Brazil. In the theoretical approach were discussed the reproductive aspects of Oedogoniaceae and Zygnemataceae families and their implication in the taxonomic and ecological studies. One hypothesis related to polyploidy was suggested to explain the low frequency of specimens bearing reproductive structures in lotic environments. Based on the materials found in southern Brazil was made a division into 12 morphotypes based essentially on cell diameter. These morphotypes were tested for their relationship with environmental variables. Finally, the ecological aspect addressed the environmental distribution of macroscopic green algae from streams of the main biomes of Southern Brazil, taking into account the richness, abundance and species composition and their relation to geographic distance and the environment variables. The results showed that the presence or absence of the group was essentially related to shading and, to a lesser degree, to pH and current velocity of the sampling segment. Once occurring in a given ... (Complete abstract click electronic access below) / Doutor

Epiphytic bacterial communities on the surfaces of marine algae are poorly characterised. Most information available on marine bacterial epiphytes is derived from culture-based studies. With the rapid development of molecular community analysis technologies, it is now possible to obtain a more comprehensive picture of marine microbial populations on living surfaces. The intertidal macroalga Ulva australis, belongs to the cosmopolitan group of green marine algae (Ulvales) known to require the presence of bacteria for normal growth and has been suggested to employ specific bacteria for the defence against fouling by micro- and macro-organisms. This thesis has examined the composition and structure of the surface associated bacterial community on Ulva australis using 16S rRNA gene clone library, denaturing gradient gel electrophoresis (DGGE), and catalysed reporter deposition ??? fluorescence in situ hybridisation (CARD-FISH) analysis. The 16S rRNA gene clone library revealed that the five main bacterial groups present in the surface associated community were Bacteriodetes, Planctomycetes, Alpha-, Gamma-, and Delta-Proteobacteria. Twenty-two sequence phylotypes were identified, suggesting that the epiphytic community was of relatively low diversity. A clone similar to an algal morphogenesis inducing Cytophaga strain was identified, indicating that U. australis harbours bacteria important for thallus structural maintenance. DGGE analysis showed that while the bacterial community varied over spatial and temporal (seasons) scales it also included a stable subpopulation consistently associated with the seaweed surface. Sequencing of selected DGGE bands suggested that members of the Alphaproteobacteria and the Bacteriodetes belonged to the stable subpopulation. Using CARD-FISH with different phylogenetic probes demonstrated that Alphaproteobacteria (~ 70%) and Cytophaga-Flavobacteria (~13%) constituted the majority of bacterial cells on the surface of U. australis. A comparison of the results provided by the molecular community analysis methods, employed in this thesis, and those of culturing of epiphytic bacteria from U. australis revealed that each approach provides different patterns of phylogeny and extent of diversity. For example, the culture collection and the clone library detected a relatively high amount of Gammaproteobacteria, however, DGGE and CARD-FISH did not. Also, low species diversity clone sequences and isolates of Alphaproteobacteria contrasted with the high numbers detected by the DGGE analysis. In addition to the phylogentic determination of the epiphytic bacterial community, CARDFISH was also used to assess the organisation and distribution of bacterial cells across different zonal regions on seaweed surface. It was found that approximately 40% of bacterial cells clustered in aggregates, or microcolonies. These aggregations were considered to be heterogeneous in composition and were mainly comprised of multiply species. The occurrence of more non-viable solitary single rather than aggregated cells suggests that aggregates might offer greater protection to bacterial cells from the harsh conditions in the intertidal zone. More broadly, CARD-FISH was found to be a useful tool for studying microcolonies and was also successfully applied to detect slow growing soil microcolonies cultivated using a novel soil substrate membrane system culturing technique without the need to perform an rRNA enrichment incubation. The findings in this thesis, as described from the application of a number of molecular community analysis techniques such as clone library, DGGE and CARD-FISH, have improved our understanding of the diversity and structure of the epiphytic bacterial community associated with U. australis. Morevover, the information provided may to design future studies in the ecology of bacteria-seaweed interactions, including symbiotic interactions, and aid in marine biotechnology applications such as identifying bacteria which produce bioactive secondary metabolites.

Thesis (M.Sc.)--York University, 2000. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 65-72). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pMQ56165

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