Navegando por Autor "Passos, Frederico José Vieira"
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Item ATP - bioluminescence as a technique to evaluate the microbiological quality of water in food industry(Brazilian Archives of Biology and Technology, 2000-07) Costa, Patrícia Dolabela; Andrade, Nélio José de; Passos, Frederico José Vieira; Brandão, Sebastião César Cardoso; Rodrigues, Carolina Gonçalves FreireATP-bioluminescence was used to evaluate the microbiological quality of water samples collected from the water supply, the water treatment system and from a dairy plant, including ammonia-cooling water and industrial water. For industrial water, there was relation between the ATP-bioluminescence technique and microbial count. There were no differences (p>0.05) between water supply and ammonia-cooling water samples for total and free ATP concentrations nor for the microbial counts. Different microbial ATP concentrations were found for these water samples. The results suggested that the physical chemical quality of ammonia cooling water decreased the RLU measurements slightly. It could be concluded that the total ATP concentration was the most effective technique to evaluate the microbiological quality of water used in the food indsutry by ATP-bioluminescence.Item Avaliação do comportamento de um substrato sintético e de um efluente de suinocultura no tratamento anaeróbio de reatores uasb(Revista Ceres, 2006-05) Olmi, Vanessa Riani; Pires, Aline Mara Barbosa; Ramos, Alcinéia de Lemos Souza; Kameyama, Oswaldo; Mancilha, Ismael Maciel de; Passos, Frederico José VieiraO presente trabalho teve como objetivo avaliar o desempenho de reatores UASB alimentados com efluente natural de suinocultura (controle) e substrato sintético, empregando-se dois níveis de cargas biológicas para cada substrato (0,2 e 0,4 ngQO.KgS VT'1.d'1), com a finalidade de avaliar o uso de substrato sintético como substituto ao efluente natural de suinocultura, em experimentos onde seja difícil sua utilização. Os resultados mostraram que o substrato sintético apresentou um comportamento bastante similar ao controle, observando-se que os reatores alcançaram o regime permanente após aproximadamente 40-45 dias de operação. Para ambos os substratos, quanto maior a carga orgânica volumétrica aplicada, menor a eficiência de remoção de DQO alcançada. A similaridade no comportamento, tanto em relação a remoção de matéria orgânica, quanto a estabilidade do sistema, aponta para a possibilidade da utilização de substrato sintético em experimentos de avaliação de sistemas de tratamento de efluente de suinocultura.Item Interference of some organic substances and microorganisms adhered to stainless steel in ATP-bioluminescence measurement(Brazilian Archives of Biology and Technology, 2008-05) Simm, Erny Marcelo; Andrade, Nélio José de; Mendonça, Regina Célia Santos; Passos, Frederico José Vieira; Chaves, José Benício PaesAdhesion of organic substances and microorganisms on stainless steel surface was evaluated. The log RLU measurement was affected at a lower or higher degree, by type or concentration of the organic substances (casein, lipid, sucrose and their combinations) adhered to surface. However, if the samples analyzed were from the food processing surfaces, they would have been considered to be under satisfactory hygienic conditions with log RLU < 2.18 (< 150 RLU). The log RLU measurements of Staphylococcus carnosus-adhered surfaces, combined with or without the organic substances, were higher (p<0.05) than those of the Bacillus subtilis spores-adhered surface, regardless of the concentration. The samples taken from the surfaces adhered with the casein, lipid, sucrose and 2.9x101 DMC.cm-2 and 2.9x102 DMC.ml-1 did not have any significant differences (p≥0.05) on ATP-bioluminescence measurements. However, the surfaces adhered with 2.9x103 DMC.cm-2 of B. subtilis spores and organic substances showed an increase in the log RLU measurement compared to surfaces containing only the organic substances.Item Kinetics of growth and ethanol formation from a mix of glucose/xylose substrate by Kluyveromyces marxianus UFV-3(Antonie van Leeuwenhoek, 2012-09-11) Passos, Flávia Maria Lopes; Santos, Valdilene Canazart dos; Bragança, Caio Roberto Soares; Passos, Frederico José VieiraThe fermentation of both glucose and xylose is important to maximize ethanol yield from renewable biomass feedstocks. In this article, we analyze growth, sugar consumption, and ethanol formation by the yeast Kluyveromyces marxianus UFV-3 using various glucose and xylose concentrations and also under conditions of reduced respiratory activity. In almost all the conditions analyzed, glucose repressed xylose assimilation and xylose consumption began after glucose had been exhausted. A remarkable difference was observed when mixtures of 5 g L^−1 glucose/20 g L^−1 xylose and 20 g L^−1 glucose/20 g L^−1 xylose were used. In the former, the xylose consumption began immediately after the glucose depletion. Indeed, there was no striking diauxic phase, as observed in the latter condition, in which there was an interval of 30 h between glucose depletion and the beginning of xylose consumption. Ethanol production was always higher in a mixture of glucose and xylose than in glucose alone. The highest ethanol concentration (8.65 g L^−1) and cell mass concentration (4.42 g L^−1) were achieved after 8 and 74 h, respectively, in a mixture of 20 g L^−1 glucose/20 g L^−1 xylose. When inhibitors of respiration were added to the medium, glucose repression of xylose consumption was alleviated completely and K. marxianus was able to consume xylose and glucose simultaneously.Item Production of pectin lyase by Penicillium griseoroseum in bioreactors in the absence of inducer(Brazilian Journal of Microbiology, 2001-04) Passos, Flávia Maria Lopes; Passos, Frederico José Vieira; Silva, Daison Olzany; Piccoli-Valle, Roberta HilsdorfPenicillium griseoroseum was grown in bioreactors on mineral medium supplemented with yeast extract and sucrose. The influence of inoculum and carbon source concentrations, aeration and pH on pectin lyase (PL) production, as well as the capacity of P. griseoroseum to produce PL when grown on sugar cane syrup as carbon source were evaluated. Inoculum concentration did not influence PL production. Production was higher in non-aerated than in aerated medium. The best results were obtained using 60 mM sucrose at pH 6.3-7.2. Production using cane syrup 25% (v/v), without yeast extract supplement, was equal to that obtained under the conditions cited above.Item Signals of aging associated with lower growth rates in Kluyveromyces lactis cultures under nitrogen limitation(Canadian Journal of Microbiology, 2014) Corrêa, Lygia Fátima da Mata; Passos, Frederico José Vieira; Viloria, Marlene Isabel Vargas; Martins Filho, Olindo Assis; Carvalho, Andréa Teixeira de; Passos, Flávia Maria LopesThe effects of aging on the specific growth rate of Kluyveromyces lactis cultures, as a function of (NH4)2SO4 concentration, were evaluated. The growth kinetic parameters maximum specific growth rate and saturation constant for (NH4)2SO4 were calculated to be 0.44 h−1 and 0.15 mmol·L−1, respectively. Batch cultures were allowed to age for 16 days without influence of cell density or starvation. The specific growth rates of these cultures were determined each day and decreased as the population aged at different nitrogen concentrations. Aging signals (N-acetylglucosamine content of the cell wall, cell dimensions, and apoptosis markers) were measured. Apoptosis markers were detected after 5 days at limiting (NH4)2SO4 concentrations (0.57, 3.80, and 7.60 mmol·L−1) but only after 8 days at a nonlimiting (NH4)2SO4 concentration (38.0 mmol·L−1). Similarly, continuous cultures of K. lactis performed under nitrogen limitation and, at lower dilution rates, accumulated cells exhibiting aging signals. The results demonstrate that aging affects growth rate and raise the question of whether nitrogen limitation accelerates aging. Because aging is correlated with growth rate, and each dilution rate of the continuous cultures tends to select and accumulate cells with a respective age, cultures growing at lower growth rates can be useful to investigate yeast physiological responses, including aging.