Contaminant yeasts spoil pure culture fermentations and cause great losses in quality and product yields. They can be detected by a variety of methods although none being so efficient for early detection of contaminant yeast cells that appear at low frequency. Pure cultures bearing genetic markers can ease the direct identification of cells and colonies among contaminants. Fast and easy detection are desired and morphological markers would even help the direct visualization of marked pure cultures among contaminants. The GFP gene for green fluorescent protein of Aquorea victoria, proved to be a very efficient marker to visualize transformed cells in mixed populations and tissues. To test this marker in the study of contaminated yeast fermentations, the GFP gene was used to construct a vector under the control of the ADH2 promoter (pYGFP3). Since ADH2 is repressed by glucose the expression of the protein would not interfere in the course of fermentation. The transformed yeasts with the vector pYGFP3 showed high stability and high bioluminescence to permit identification of marked cells among a mixed population of cells. The vector opens the possibility to conduct further studies aiming to develop an efficient method for early detection of spoilage yeasts in industrial fermentative processes.

A simple DNA isolation method was developed with routine chemicals that yields high quality and integrity preparations when compared to some of the most well known protocols. The method described does not require the use of lysing enzymes, water bath and the DNA was obtained within 40 minutes The amount of nucleic acid extracted (measured in terms of absorbancy at 260 nm) from strains of Xanthomonas spp., Pseudomonas spp. and Erwinia spp. was two to five times higher than that of the most commonly used method.

O tomateiro é uma olerícola de grande importância econômica e uma das mais suscetíveis a viroses, dentre as quais, a causada pelo vírus do mosaico do tomateiro (ToMV), gênero Tobamovirus, que tem como sintomas mosaico verde claro-escuro nas folhas, afilamento dos folíolos e diminuição da produção, entre outros sintomas. Visando a identificação do ToMV, foram produzidos anticorpos monoclonais (MAbs), testados através de PTA- ELISA ("plate trapped antigen- enzyme linked immunoassay"). O MAb (10.H1) foi utilizado para avaliar a capacidade de identificação do ToMV em testes no campo em plantas de tomate infectadas. O MAb não apresentou reação cruzada com TMV (tobamovirus do mosaico do tabaco) nem com extrato de plantas sadias. O ToMV das amostras foi isolado, purificado e re-inoculado em plantas de tomateiro e de tabaco, para confirmação dos sintomas. Em "immunobloting" o MAb 10.H1 reconheceu somente a proteína referente à capa protéica do ToMV (de 17,5 kDa). A especificidade do MAb 10.H1 pode permitir o diagnóstico precoce desta doença na fase de plântulas, ainda em casa de vegetação, evitando assim a disseminação desta virose no campo.

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One of the problems in waste water treatment plants (WWTPs) is the increase in emissions of hydrogen sulphide (H2S), which can cause damage to the health of human populations and ecosystems. To control emissions of this gas, sulphur-oxidizing bacteria can be used to convert H2S to sulphate. In this work, sulphate detection was performed by spectrophotometry, ion chromatography and atomic absorption spectrometry, using Paracoccus pantotrophus ATCC 35512 as a reference strain growing in an inorganic broth supplemented with sodium thiosulphate (Na2S2O3·5H2O), sodium sulphide (Na2S) or sodium sulphite (Na2SO3), separately. The strain was metabolically competent in sulphate production. However, it was only possible to observe significant differences in sulphate production compared to abiotic control when the inorganic medium was supplemented with sodium thiosulphate. The three methods for sulphate detection showed similar patterns, although the chromatographic method was the most sensitive for this study. This strain can be used as a reference for sulphate production in studies with sulphur-oxidizing bacteria originating from environmental samples of WWTPs.

No abstract

Uptake of nutrients and cadmium (Cd) are dependent upon many factors, including plant species, ions concentration and pH. Tolerance to Cd-induced oxidative stress can be modulated by phytohormones such as abscisic acid (ABA), which induce the production of reactive oxygen species, activating proteins and enzymes involved in stress response and possibly stress tolerance. The present study aimed to evaluate the biochemical variations induced by Cd in ABA-deficient sitiens tomato mutant (sit) and its wild-type counterpart, Micro-Tom (MT), grown at different pH conditions. The plants were cultivated in nutrient solution (pH 5, 6 and 7; 20-days) and were then further grown over a 48-h period in 0 or 50 µM CdCl 2 at pH 6. Before Cd addition, the concentrations of nitrogen, sulfur, copper, iron and zinc were determined and variations in nutrients

Several plants use secondary metabolites against insects and pathogens attack. Among such metabolites known glycoalkaloids are the most studied. Plants from Solanaceae Family are the most abundant on those alkaloids. Despite alfa-tomatine is a known glycoalkaloid, its specific action against Moniliophthora perniciosa, fungi responsible for witches broom disease in cocoa plantations was obtained in this work. Alfa-tomatine was infusion-extracted from Solanum lycopersicum leaves, and its action against the fungi growth was shown on the bioassays. In these tests, M. perniciosa growth was totally inhibited but other fungus tested, the inhibition was not totally, or did not present effect on growth, showing in this way, the specificity of alfa-tomatine to M. perniciosa. The advantages of work with a natural molecule for the fungi control is the stability of the molecule, its resistance to high temperature and pressure and for its use, the simple method of extraction used. The confirmation of the alfa-tomatine molecule was done by High Performance Liquid Chromatography and Mass Spectrometry in comparison to the Sigma standard.