As contaminações por leveduras selvagens e por bactérias no processo de produção de etanol combustível no Brasil causam prejuízos ao rendimento fermentativo e aumento de custos pelo uso de biocidas. No entanto, poucos estudos tem focado no efeito das contaminações conjuntas de leveduras selvagens e bactérias e as possíveis interações entre os micro-organismos, especialmente em função dos diferentes substratos de fermentação e das formas de controle. Este trabalho teve por objetivos verificar o efeito do substrato (caldo de cana e melaço) sobre o desenvolvimento das contaminações pela levedura da espécie Dekkera bruxellensis e pela bactéria Lactobacillus fermentum, em co-culturas com Saccharomyces cerevisiae (linhagem industrial PE-2) e possíveis formas de controle do crescimento dos contaminantes (pelo uso de metabissulfito de potássio e adição de etanol ao tratamento ácido) sem afetar a levedura do processo. Os testes foram realizados em condições de crescimento (substrato com 4 °Brix, culturas agitadas) e fermentação com reciclo celular (substrato com 16 °Brix, culturas estáticas). Houve interação entre as leveduras e a bactéria quando crescidas em caldo de cana 4 °Brix. A levedura industrial não foi afetada pela presença dos micro-organismos contaminantes, no entanto, para D. bruxellensis a presença de L. fermentum interferiu positivamente no crescimento, com aumento no número de UFC, e consequentemente inibição do crescimento da bactéria. Em melaço, houve um estímulo ao crescimento de L. fermentum quando em co-cultura com S. cerevisiae. Houve influência das contaminações sobre os parâmetros avaliados no experimento (pH, açúcar redutor total, etanol, glicerol e crescimento das células) e a contaminação conjunta de L. fermentum e D. bruxellensis potencializou o efeito das contaminações pelos micro-organismos isoladamente, tanto em caldo quanto em melaço. A adição de 13% de etanol à solução de ácido sulfúrico pH 2,0 no tratamento celular resultou em uma diminuição significativa no número de UFC de D. bruxellensis (entre 90-99%). A levedura PE-2 foi pouco afetada pelo tratamento proposto. A bactéria L. fermentum teve seu crescimento afetado em todas as combinações testadas. Como os experimentos foram feitos em co-culturas, verificouse que pode haver influência de um micro-organismo sobre a viabilidade do outro, dependendo da reação ao tratamento ácido-etanol. O metabissulfito de potássio (MBP), no intervalo entre 200-400 mg/L, foi eficaz para controlar o crescimento de D. bruxellensis dependendo do meio de cultura e linhagem. Quando adicionado (250 mg/L) à solução ácida (pH 2,0) no tratamento celular, um efeito significativo foi observado nas culturas mistas, pois ocorreu a inativação do SO2 pela S. cerevisiae e uma provável proteção das células de D. bruxellensis, não sendo essa levedura prejudicada pelo MBP. A resposta fisiológica de S. cerevisiae na presença de MBP pode explicar a diminuição significativa na produção de etanol. Quando o MBP foi adicionado ao meio de fermentação, resultou no controle da D. bruxellensis mas não em sua morte, com efeito menos intensivo sobre a eficiência fermentativa. Em cocultura com a adição de MBP, a eficiência fermentativa foi significativamente menor do que na ausência de MBP. / The contaminations by wild yeasts and bacteria are harmful to the fermentative process for fuel ethanol production in Brazil due to the decrease in ethanol yield and increase in the industrial costs by the use of biocides. However, a few studies have been focused in the effects of simultaneous contaminations of wild yeasts and bacteria and the possible interactions among the microorganisms, especially concerning different fermentation substrates and forms of growth control. This work aimed to verify the effect of the substrate (sugar cane juice and molasses) on the development of contaminations by Dekkera bruxellensis yeast and Lactobacillus fermentum bacteria, in co-cultures with Saccharomyces cerevisiae (industrial strain PE-2) and possible forms of growth control of the contaminants (using potassium metabisulphite and addition of ethanol to the acid treatment) without affecting the starter yeast. Tests were carried out in growing conditions (substrate with 4 °Brix, shaken cultures) and cell-recycled fermentation (substrate with 16 °Brix, static cultures). There was interaction among the yeasts and the bacteria when growing in sugarcane juice 4 °Brix. The industrial yeast strain was not affected by the presence of the contaminant microorganisms, however, for D. bruxellensis, the presence of L. fermentum influenced positively the growth, increasing the number of CFU and consequently inhibiting the bacterial growth. In molasses, there was an increase in the growth of L. fermentum when in co-culture with S. cerevisiae. The contaminations influenced the fermentative parameters (pH, total reducing sugars, ethanol, glycerol and cell growth) and the simultaneous contamination by L. fermentum and D. bruxellensis potentiated the effect of the contaminations isolately, both in sugarcane juice as in molasses. The combined effect of pH 2.0 + 13% ethanol in the cell treatment resulted in a significant decrease (90-99%) in the CFU number of D. bruxellensis. The industrial yeast PE-2 was a little affected by the treatment. The growth of the bacteria L. fermentum was affected in all the combinations tested. As the experiments were performed with co-cultures, an influence of a microorganism over the viability of another was observed, depending of the reaction to the treatment. The potassium metabisulphite (PMB), in the range of 200-400 mg/L, was effective to control the growth of D. bruxellensis depending on the culture medium and strain. When added (250 mg/L) to the acidic solution (pH 2.0), a significant effect was observed in mixed cultures, because the inactivation of SO2 by S. cerevisiae most likely protected D. bruxellensis from being damaged by PMB. The physiological response of S. cerevisiae to the presence of PMB may explain the significant decrease in alcohol production. When added to the fermentation medium, PMB resulted in the control but not the death of D. bruxellensis, with less intensive effect on the fermentative efficiency. In co-culture with the addition of PMB, the fermentative efficiency was significantly lower than in the absence of PMB.

No presente trabalho foram realizadas análises de enterobactérias e Salmonella em cecos e papos de frangos de corte criados sem reaproveitamento de cama e com baixa densidade, submetidos a períodos de jejum de 3, 6, 9, 12, 15 e 18 horas; também foram feitas análises das mesmas bactérias, incluindo esporos de Bacillus subtilis e bactérias ácido lácticas em papos e cecos de frangos de corte alimentados com probióticos (bactérias lácticas, Bokashi e esporos de B. subtilis) e antibiótico (bacitracina de zinco) nas rações. Não houve diferença significativa entre as populações de enterobactérias nos períodos de jejum analisados, e não foram isoladas cepas de Salmonella nos diferentes tratamentos. Houve diminuição significativa na população de enterobactérias nos cecos em relação ao grupo controle quando os frangos foram alimentados com bactérias ácido lácticas nas rações. Com Bokashi e antibiótico nas rações, a população de enterobactérias nos cecos foi maior que no grupo controle. Nos papos, não houve diferença significativa entre as populações de enterobactérias para os diferentes tratamentos, mas o tratamento com Bokashi foi o que obteve menor população das enterobactérias nesse habitat. As contagens de bactérias ácido lácticas e esporos de B. subtilis dos cecos e papos analisados não sofreram alteração significativa devido aos diferentes aditivos presentes nas rações, quando comparadas ao grupo controle. Novamente não foram isoladas cepas de Salmonella nos cecos e papos dos frangos analisados. A ausência de Salmonella pode ter explicação no modo de criação dos frangos, com baixa densidade (12 aves/m2) e sem reaproveitamento de cama, pois foi um resultado encontrado nas duas fases do trabalho. A diminuição de enterobactérias nos cecos por parte das bactérias ácido lácticas administradas na ração pode ter sido devido à exclusão competitiva, apesar da população dessas bactérias não ter aumentado significativamente neste habitat. O tratamento com administração de Bokashi obteve menor contagem de enterobactérias no papo possivelmente devido ao fato de ser um produto fermentado, com pH baixo, que poderia agir prontamente no papo. A administração de esporos de B. subtilis não surtiu efeito nas populações das bactérias analisadas nos cecos e papos dos frangos de corte. / This study analyzed the population of enterobacteria and Salmonella in the crop and caeca of broiler chickens submitted to 3, 6, 9, 12, 15 and 18 hours of feed withdrawal, and raised without reutilization of the litter, in low density. The same bacteria were analyzed, plus Bacillus subtilis spores and lactic acid bacteria, in the crop and caeca of broiler chickens fed rations with probiotics (lactic acid bacteria, Bokashi and B. subtilis spores) and antibiotic (zinc bacitracin). There were no significant differences between enterobacteria populations on the analyzed withdrawal periods, and Salmonella and antibiotic (zinc bacitracin). There were no significant differences between enterobacteria populations on the analyzed withdrawal periods, and B. subtilis spores populations from the caeca and crops of analyzed broiler chickens did not differ from the control group when the different additives were fed through the ration. Again there were no Salmonella isolates in the analyzed crop and caeca. The absence of Salmonella may have an explanation on the way that chickens were raised, with low density (12 birds/m2) and no litter reutilization, because this result was found on the two phases of the study. The lower caeca enterobacteria population found when the broilers were fed lactic acid bacteria may have been due to competitive exclusion, even though the lactic acid bacteria counting did not increase significantly in this habitat. Treatment with Bokashi administration had lower counting of enterobactérias in the crop, possibly due to the fact that Bokashi is a fermented product, with low pH, that could act readily in the crop. The administration of B. subtilis spores did not have any effect on the populations of the analyzed bacteria, in the crop and caeca of broiler chickens.

A espécie Dekkera bruxellensis tem sido detectada como a principal levedura contaminante em diversos processos fermentativos, dentre eles o de produção de etanol combustível, apresentando uma surpreendente capacidade de crescimento e adaptação naqueles substratos. No entanto, pouco se conhece sobre suas características de crescimento em condições de estresse e comportamento fermentativo. Desta forma, este trabalho objetivou avaliar a tolerância ao estresse e as características fermentativas exibidas por três linhagens de D. bruxellensis isoladas da fermentação alcoólica, além do efeito da contaminação em mosto de caldo de cana sobre os parâmetros fermentativos, buscando informações que possam contribuir para o manejo da fermentação alcoólica quando contaminada com esta levedura. Foram realizados testes de caracterização em meio YEPD sólido e líquido em condições estressantes para as três linhagens de D. bruxellensis e uma linhagem de S. cerevisiae (PE-02). O efeito do tratamento ácido associado ao etanol sobre a viabilidade das quatro linhagens em situação de agitação e sem agitação foi também avaliado. Em seguida, testes fermentativos em meio sintético (sem reciclo celular) e em meio de caldo de cana (com reciclo celular e utilizando-se ou não tratamento ácido) foram conduzidos para verificar as características fermentativas das linhagens de D. bruxellensis em comparação com S. cerevisiae, simulando-se uma contaminação por 103 células/mL da linhagem CCA155 em meio de caldo de cana. As três linhagens de D. bruxellensis apresentaram crescimento invasivo em meio YEPD sólido, possivelmente um mecanismo de sobrevivência da levedura em condições estressantes. Observou-se uma variação na resposta das linhagens às situações de estresse (baixo pH e alta concentração de etanol). Em condições não estressantes, a linhagem PE-02 apresentou melhor desenvolvimento, no entanto, em situações de estresse de pH, concentrações de açúcar e etanol, as linhagens de D. bruxellensis desenvolveram-se melhor. O controle eficiente do crescimento destas leveduras poderia ser obtido com um tratamento combinado de baixo pH (1,5) e etanol (9%), porém houve também prejuízo significativo à levedura S. cerevisiae, embora em menor extensão. Em sistema de batelada sem reciclo celular em meio sintético, verificou-se que a agitação influenciou significativamente a produção de etanol e ácidos por D. bruxellensis. O teor alcoólico foi maior quando se utilizou glicose como fonte de carbono ao invés de sacarose. Em sistema de batelada com reciclo celular em meio de caldo de cana, foram obtidos melhores resultados quanto à produção de etanol, menor teor de açúcar redutor total residual e maior eficiência fermentativa quando se utilizou o tratamento ácido do fermento (pH 1,5), assim como melhor controle do crescimento da linhagem CCA155 quando em cultura mista com S. cerevisiae (PE-02). O tratamento ácido utilizado teve efeito não só sobre o crescimento da levedura contaminante, mas também beneficiou a levedura do processo, resultando assim na minimização do efeito da contaminante sobre a fermentação conduzida em meio de caldo de cana sob dez ciclos fermentativos de 12 horas. / The species Dekkera bruxellensis has been considered as the main contaminant yeast in several fermentative processes, including the fuel alcohol production, showing a surprising growth capacity and adaptation in those substrates. However, a little is known about their growth characteristics in stressing conditions and fermentative profile. In this context, this work aimed to evaluate the stress tolerance and fermentative characteristics exhibited by three strains of D. bruxellensis isolated from the alcoholic fermentation, besides the effect of the contamination in sugar cane juice over the fermentative parameters, searching for information that could contribute to the management of the alcoholic fermentation when the medium is contaminated with this yeast. Characterization tests in YEPD medium (solid and liquid) under stressing conditions for the D. bruxellensis and S. cerevisiae (PE-02) strains were carried out. The effect of the acid treatment associated with ethanol over the cell viability of the four strains in shaken and non-shaken flasks was also evaluated. Following, fermentative tests in synthetic medium (without cell recycle) and in sugar cane juice (with cell recycle and with/without acid treatment) were carried out to verify the fermentative characteristics of the strains of D. bruxellensis comparing to S. cerevisiae, simulating a contamination by 103 cells/mL of the strain CCA155 in sugar cane juice. All the strains of D. bruxellensis showed invasiveness in YEPD agar medium, probably a survival mechanism in stressful conditions. A variation in the response of the strains to the stressing conditions (low pH and high ethanol concentration) was observed. In nonstressing situations, the strain PE-02 showed better growth; however, in stressing conditions of pH, ethanol and sugar concentrations, the strains of D. bruxellensis had better growth performance. The effective control of their growth could be obtained with a combined treatment of low pH (1.5) and ethanol (9%), however, a significant harmful effect to the S. cerevisiae strain was also verified, but in a lower extension. In batch system without cell recycle in synthetic medium, it was verified the influence of agitation over the ethanol and acid production by D. bruxellensis. The alcohol content was significantly higher when glucose was utilized instead of sucrose. In batch system with cell recycle in sugar cane juice, the best results for ethanol production, lower residual total reducing sugar and higher fermentative efficiency were obtained with the acid treatment of the ferment at pH 1.5, as well as a better growth control of the strain CCA155, in mixed culture with S. cerevisiae (PE-02). The acid treatment utilized in this work had effect not only over the growth of the contaminant yeast, but also benefited the yeast S. cerevisiae, resulting in the minimization of the effect of the contaminant over the fermentation developed in sugar cane juice medium in 12-hour ten fermentative cycles.

Este estudo trata da criação em dança com mediação tecnológica observando os procedimentos de criação em videodança analisados pelas perspectivas do artista Gustavo Gelmini e do processo de criação da videodança “Alegoria do Veado Ferido” (2017) de minha proposição. Esta pesquisa de caráter qualitativo utiliza como estratégias metodológicas entrevistas semiestruturadas com o artista bem como o relato de experiência na criação da videodança supracitada. A discussão teórico-metodológica percorre algumas pistas do campo da dança e da comunicação para responder à principal questão que mobiliza esta investigação: como as estratégias de criação em dança com mediação tecnológica nos permitem apreender os modos de virtualização dos corpos engajados no fazer videodança? A pesquisa tem por objetivo refletir sobre a prática das danças criadas para o vídeo problematizando as questões do corpo enquanto presença, materialidade, virtualidade, bem como de suas relações com o meio. Justifica-se por buscar oferecer caminhos de compreensão para a dança na contemporaneidade, aproximando e entendendo como relacionais as incidências destes outros corpos bem como de suas virtualidades. Conclui-se na elaboração do princípio de contaminação entre corpo, dança e tecnologia como instrumento pertinente à criação em videodança. / This study deals with the creation in dance with technological mediation observing the procedures of creation in videodance analyzed by the perspectives of the artist Gustavo Gelmini and the creation process of the videodance "Allegory of the Injured Deer" (2017), of my proposition. This research of qualitative character uses as methodological strategies semi-structured interviews with the artist, as well as the report of experience in the videodance creation mentioned above. The theoreticalmethodological discussion goes through some clues in the field of dance and communication to answer the main question that mobilizes this investigation: how do dance creation strategies with technological mediation allow us to apprehend the virtualization modes of bodies engaged in videodance? The research aims to reflect on the practice of dances created for the video, problematizing the body's questions as presence, materiality and virtuality, as well as its relations with the environment. It is justified by seeking to offer ways of understanding dance in contemporaneity, approaching and understanding as relational the incidences of these other bodies as well as their virtualities. It is concluded in the elaboration of the principle of contamination between body, dance and technology as a pertinent instrument to the creation in videodance.

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The thesis deals with the contamination of the workspace with a liquid aerosol, which is generated by scattering and evaporation of the cooling fluid. Cooling fluid are primarily intended to lubricate, cool and clean the tool and the workpiece, but the unwanted side effect is the formation of a liquid aerosol that holds in the air of the workspace. In such a contaminated work environment, the operator is exposed to a certain dose of a liquid aerosol that causes dermatological and respiratory problems. The topic of the thesis was to find out the number of particles of liquid aerosol that arises under varying working conditions and its dispersion in space. This amount was determined by image analysis using a high-speed camera.

The main aim of this experimental work is to describe, based on laboratory experiments, how the change of lubricant condition affects friction and wear of the lubricated node. The changes studied will be contamination of the oil with moisture, solid particles and its oxidative degradation. For this purpose, a tribometer in a block-on-ring configuration and a back-to-back device will be used.

Brownfields are one of the unfavorable parts of industrial heritage that developed from 18th to 20th century. Brownfields are very different and in most cases they have negative impact on the environment. Crucial for this thesis were brownfields with certain level of contaminations. The site of a former refinery of mineral oils OSTRAMO, which represents ecological burden, is a brownfield that can threaten the environment in all its compartments. This was the reason why OSTRAMO was selected for this thesis. The goal of this thesis was to evaluation of ecotoxicological effects of contaminated samples taken from the location via ecotoxicity testing in aquatic and contact arrangement. The result of each test confirmed expected negative impact of the samples from the location of former rafinery on testing organisms.

A deteriorating trend has been noted in the bacteriological quality of surface irrigation water sources in South Africa. In a bid to compare the bacteriological quality of two irrigation water sources as well as whether irrigation water was a source of bacterial pathogens on irrigated lettuce, this study was designed and divided into two phases. Phase one involved determination of physico-chemical parameters and bacterial indicators in the Loskop canal, the Skeerpoort river and lettuce irrigated with water from the Skeerpoort river over 10 months. Co-currently the study further determined the diversity of the most prevalent bacterial microflora in the 3 sample sources over the same time period. Aerobic colony counts (ACC), Aerobic spore formers (ASF), Anaerobic spore formers (AnSF), Faecal coliforms (FC), Intestinal enterococci (IE) and Staphylococcus aureus (S. aureus) as well as prevalence of Escherichia coli (E. coli), Salmonella spp and Listeria monocytogenes (L. monocytogenes) were determined. Additionally the most prevalent aerobic bacterial species isolated from the three sources were determined. Higher mean rainfall was noted in areas surrounding the Skeerpoort river (74.7mm) than the Loskop canal (0.1mm). Mean temperature was 15.4˚C and 18.2˚C while mean pH was 7.4 and 8.4 in the Loskop canal and the Skeerpoort river respectively. Low mean bacterial counts of less than 3.4 log10cfu/ml, were noted for ACC, ASF, AnSF, S. aureus and IE at both irrigation sites. Higher mean ACC of 5.9 log10cfu/g and S. aureus counts of 3.0 log10cfu/g were noted on lettuce. Although low mean counts of FC (1.3 log10cfu/100ml) were noted for all three sources, high incidence of E. coli was observed during bacterial composition studies on nonselective media. This suggested underestimation of faecal contamination possibly indicating that identification of specific pathogens provided a better measure of assessing bacterial contamination than bacterial indicators. E. coli, Bacillus spp and Enterobacter spp were the most prevalent bacteria in the Loskop canal, the Skeerpoort river and on lettuce. Prevalence of E. coli, Bacillus spp and Enterobacter spp in the Loskop canal was 23%, 33% and 26% respectively. Similarly prevalence in the Skeerpoort river was 36%, 26%, 16% respectively. On lettuce prevalence of the same bacteria was 36%, 30% and 6% respectively. E. coli O157:H7 was isolated at both irrigation sites while Salmonella enterica (gp 1) ST paratyphi A was isolated from the Skeerpoort river. High prevalence of similar bacterial species within the Loskop canal and the Skeerpoort river suggested similar sources of contamination in the two water sources inspite of different geographical location and surrounding land use practices. Additionally, similar bacterial species in irrigation water from the Skeerpoort river and on irrigated lettuce suggested water as a source of contamination on produce. Additionally it suggests ability of bacterial pathogens to withstand environmental conditions under field conditions which may pose a risk to food safety and public health among individuals consuming irrigated fresh produce. Phase 2 aimed at determining the prevalence of antibiotic resistant and virulent E. coli collected from the Loskop canal, the Skeerpoort river and lettuce irrigated with water from the Skeerpoort river. Forty one (41) E. coli isolates: (19) Loskop canal; (12) the Skeerpoort river; (10) lettuce were tested with 11 antibiotics at single concentrations and screened for Shigatoxin 1 (stx 1), Shigatoxin 2 (stx 2) and intimin (eae) genes. Antibiotic resistance was also used as a means of clustering E. coli isolated from the 3 sources. In the Loskop canal 84% and 83% of strains in the Skeerpoort river were resistant to at least one antibiotic. There was a significant difference (p≤0.05) in resistance to antibiotics between isolates from the Loskop canal and the Skeerpoort river. Additionally the combined effect of isolate source (irrigation water site) and antibiotics for isolates from the Skeerpoort river was significant (p≤0.05). From lettuce, 90% of isolates were resistant to at least one antibiotic and resistance significantly differed (p≤0.05) from isolates in the Skeerpoort river. The highest resistance to single antibiotics in all three samples was to cephalothin and ampicillin. Higher resistance was noted to multiple (more than 2) antibiotics in the Skeerpoort river (33%) than Loskop canal (5%). Most isolates from the same source showed close relatedness. Close relatedness was noted between isolates from the Loksop canal (10.5%) and the Skeerpoort river (16%). From irrigated lettuce 40% of isolates showed close relatedness to isolates in irrigation water from the Skeerpoort river. In the Loskop canal 15% and 41% of isolates in the Skeerpoort river possessed virulence genes. From lettuce, 20% of isolates possessed virulence genes. In the Loskop canal as well as from lettuce all isolates with virulence genes were antibiotic resistant while 80% of isolates with virulence genes in the Skeerpoort river were antibiotic resistant. In the Loskop canal 10% and 25% of isolates in the Skeerpoort river were positive for stx1/stx2 and eae, genes synonymous with Enterohaemorrhagic E. coli (EHEC). Results from this study show that E. coli from the two irrigation water sources as well as on irrigated lettuce were resistant to antibiotics and potentially pathogenic. This may increase risk of contaminating irrigated fresh produce which may compromise food safety and public health of consumers. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Food Science / unrestricted