Antonio Roberto Navarro

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An invertase (beta-D-fructofuranoside fructohydrolase, EC from Rhodotorula glutinis was purified by ammonium sulfate fractionation, gel filtration and anion exchange chromatography. Invertase molecular weight was estimated to be 100 kDa by analytical gel filtration and 47 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).(More)
Different inocula with high yeast concentration were investigated as a means of overcoming the inhibitory effect of furfural in ethanol fermentation. In order to verify the toxicity of the furfural, a series of fermentation runs were made with 0.25, 5.50, and 9.00 g/L (dry weight) ofSaccharomyces cerevisiae inoculum and 1, 3, and 5 g/L of furfural. The(More)
Alicyclobacillus acidoterrestris is a thermoacidophilic, non-pathogenic, spore-forming bacterium detected in spoiled commercial pasteurized fruit juice. Apple, white grape and tomato are particularly susceptible. A. acidoterrestris spores are resistant to lemon juice pasteurization (2 min at 82°C), and they can germinate and grow causing spoilage. This(More)
Aspergillus sp strains from decaying lemons were tested for extracellular pectinase production, testing differently pretreated lemon peel as the carbon source instead of pectin. It was found that the production of extracellular polygalacturonase was about the same and that of pectinesterase substantially higher when unwashed fresh lemon peel was used(More)
Antifungal proteins produced by Bacillus sp. IBA 33 were purified by ammonium sulfate precipitation and DEAE-Sephacel column chromatography. The two purified proteins inhibited the growth of Geotrichum candidum, the sour rot disease agent in lemon. The proteins were stable at 20 (3 months), 40, 60 and 100°C (30 min) and remained active after sterilization(More)
The effects of inoculum size on the kinetics of ethanol fermentation are not well defined in the literature. The purpose of this article is to examine the influence of the initial cell concentration on the modeling of ethanol inhibition. Experimental results show that increasing the inoculum level decreases the severity of ethanol inhibition. The effect of(More)
Yeasts cells (Saccharomyces cerevisiae) were immobilized by occlusion in pectin gel, no significant changes in their biological activity being observed. The ethanol production rate was found to be negatively affected by the diameter of the beads when the cell concentration in them was high. The fermentative activity was only slightly modified by pectin(More)
Numerous species of filamentous fungi were isolated from lemon on different plantations in the province of Tucuman, Argentina. The techniques suggested by the Subcommittee of Antifungal Susceptibility of the National Committee for Clinical Laboratory Standards, (USA) were adapted. The effect of three different concentrations of the fungicides imazalil,(More)
Yeast cells (Saccharomyces cerevisiae) were immobilized in pectin gel, incubated 12 h at 30°C and then used for the continuous production of ethanol employing a wedge-shaped horizontal reactor and sugar cane molasses as the carbon source. Under steady state conditions the mean residence time was 1.6 h and the volumetric productivity 40 g EtOH/hl. The gas(More)
Geotrichum citri-aurantii is a postharvest phytopathogenic fungus of lemons. We studied the mode of action of antifungal metabolites from Bacillus sp. strain IBA 33 on arthroconidia of G. citri-aurantii. These metabolites are lipopeptides belonging to the iturin family. Membrane permeabilization of G. citri-aurantii was analyzed and mitochondrial(More)