Microbiologia
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11840
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Item Basidiosporogenesis, meiosis, and post-meiotic mitosis in the ectomycorrhizal fungus Pisolithus microcarpus(Fungal Genetics and Biology, 2010-03-03) Campos, André Narvaes da Rocha; Costa, Maurício DutraPisolithus microcarpus (Cooke and Massee) G. Cunn. is a model organism for the studies on the ecology, physiology, and genetics of the ectomycorrhizal associations. However, little is known about the basidiosporogenesis in this species and, in particular, the nuclear behavior after karyogamy. In this work, the events involved in basidiosporogenesis and meiosis in P. microcarpus were analyzed using fluorescence and scanning electron microscopy. The basidia are formed inside peridioles by the differentiation of the cells along the whole hyphae. Basidial cells measure 12–18 μm in length and 6–7 μm in diameter. P. microcarpus produces eight basidiospores per basidium imbibed in a gelatinous matrix in the basidiocarp. The basidiospores are globose, equinate, with blunt spines, and measure 6–8 μm. Karyogamy can take place inside basidia as well as in undifferentiated hyphal cells followed by nuclear migration to a newly developed basidium where meiosis takes place. After the formation of the meiotic tetrad, one round of post-meiotic mitosis occurs, resulting in the production of eight nuclei per basidium. The newly-formed nuclei migrate into the basidiospores asynchronously, resulting in the production of eight uninucleate spores. This corresponds to pattern A of post-meiotic mitosis. This work is the first report on meiosis and post-meiotic mitosis during basidiosporogenesis in P. microcarpus and contributes to clarify some aspects of the biology and genetics of this ectomycorrhizal species.Item Ethanol production from cheese whey permeate by Kluyveromyces marxianus UFV-3: a flux analysis of oxido-reductive metabolism as a function of lactose concentration and oxygen levels(Enzyme and Microbial Technology, 2005-05-16) Silveira, W. B.; Passos, F. J. V.; Mantovani, H. C.; Passos, F. M. L.In order to investigate the effect of lactose concentration and oxygen level on the growth and metabolism of Kluyveromyces marxianus UFV-3 in cheese whey permeate, batch cultures were conducted under aerobic, hypoxic, and anoxic conditions, with lactose at initial concentration ranging from 1 to 240 g L^−1. The increase in lactose concentration increased ethanol yield and ethanol volumetric productivity, and has reduced cell yield. When lactose concentration was equal or above 50 g L^−1 and the oxygen levels were low, the ethanol yield was close to its theoretical value. Maximum ethanol concentrations attained in this study were 76 and 80 g L^−1 in hipoxia and anoxia, respectively. The lactose consumption rate in anoxia was greater than in aerobiosis and hipoxia. However, under anoxia, the lactose consumption rate of K. marxianus followed a saturation kinetics, which was not observed in hypoxia and aerobiosis. All oxygen levels investigated, showed a tendency for saturation of the ethanol production rate above 65 g L^−1 lactose. Ethanol production rate was also higher on anoxia.