Time filter

Source Type

Dias R.L.,Research Center y Desarrollo en Fermentaciones Industriales | Dias R.L.,CONICET | Ruberto L.,CONICET | Ruberto L.,University of Buenos Aires | And 6 more authors.
Polar Biology | Year: 2015

Several studies have shown that biostimulation can promote hydrocarbon bioremediation processes in Antarctic soils. However, the effect of the different nutrient sources on hydrocarbon removal heavily depends on the nutrients used and the soil characteristics. In this work, using a sample of chronically contaminated Antarctic soil that was exposed to a fresh hydrocarbon contamination, we analyzed how a complex organic nutrient source such as fish meal (FM) and a commercial fertilizer (OSEII) can affect hydrocarbon biodegradation and bacterial community composition. Both amended and unamended (control) biopiles were constructed and controlled at Carlini Station and sampled at days 0, 5, 16, 30 and 50 for microbiological, chemical and molecular analyses. FM caused a fast increase in both total heterotrophic and hydrocarbon degrading bacterial counts. These high values were maintained until the end of the assay, when statistically significant total hydrocarbon removal (71 %) was detected when compared with a control system. The FM biopile evidenced the dominance of members of the phylum Proteobacteria and a clear shift in bacterial structure at the final stage of the assay, when an increase of Actinobacteria was observed. The biopile containing the commercial fertilizer evidenced a hydrocarbon removal activity that was not statistically significant when compared with the untreated system and exhibited a bacterial community that differed from those observed in the unamended and FM-amended biopiles. In summary, biostimulation using FM in biopiles significantly enhanced the natural hydrocarbon-degradation activity of the Carlini station soils in biopile systems and caused significant changes in the bacterial community structure. The results will be considered for the future design of soil bioremediation protocols for Carlini Station and could also be taken into account to deal with diesel-contaminated soils from other cold-climate areas. © 2014, Springer-Verlag Berlin Heidelberg.

Rojas N.L.,Research Center y Desarrollo en Fermentaciones Industriales | Ortiz G.E.,Research Center y Desarrollo en Fermentaciones Industriales | Baruque D.J.,CONICET | Cavalitto S.F.,Research Center y Desarrollo en Fermentaciones Industriales | Ghiringhelli P.D.,National University of Quilmes
Journal of Industrial Microbiology and Biotechnology | Year: 2011

The pg1 gene from the filamentous fungus Aspergillus kawachii, which codifies for an acid polygalacturonase, was cloned into the pYES2 expression vector, giving rise to the pYES2:pg1ΔI construct. Engineered Saccharomyces cerevisiae, transformed with pYES2:pg1ΔI construct, both expressed and exported an active polygalacturonase with a MW of ~60 kDa and an isoelectric point of 3.7, similar to those reported for the wild-type enzyme. The recombinant enzyme has the ability to hydrolyze polygalacturonic acid at pH 2.5. Heterologous PG1 production was studied under controlled conditions in batch and fed-batch systems. A simultaneous addition of glucose and galactose was found to be the most suitable feeding strategy assayed, resulting in a final PG1 production of 50 U/ml. The production process proposed in this study could be applied for the industrial production of a novel and useful polygalacturonase. © 2010 Society for Industrial Microbiology.

Medina R.,Research Center y Desarrollo en Fermentaciones Industriales | Lopez S.M. Y.,Institute Fisiologia Vegetal INFIVE | Saparrat M.C. N.,Institute Fisiologia Vegetal INFIVE | De Wit P.J.G.M.,Wageningen University | Balatti P.A.,National University of Central Buenos Aires
Plant Disease | Year: 2015

The presence of Cladosporium fulvum (syn. Passalora fulva), causal agent of tomato leaf mold, was confirmed in the two main greenhouseproduction areas for tomato in Argentina. Using both morphological characters and internal transcribed spacer sequencing, we confirmed the presence of physiological races of this pathogen. A diagnostic multiplex polymerase chain reaction (PCR) was also developed, using primers derived from C. fulvum avirulence (Avr) genes. In all, 20 isolates of Cladosporium spp. were obtained as monospore cultures and 12 were identified as C. fulvum. By this method, we showed that, of these 12 isolates, 5 were race 0 (carrying functional Avr2, Avr4, Avr4E, and Avr9 genes) and 7 were race 2 (lacking the Avr2 gene). Race identity was confirmed by testing their virulence on a set of tomato differentials carrying different Cf resistance genes. All Avr genes could be amplified in single or multiplex PCR using DNA isolated from in vitro grown monospore cultures but only three Avr could be amplified when genomic DNA was isolated from C. fulvum-infected necrotic leaf tissue. © 2015 The American Phytopathological Society.

Dias R.L.,Comision de Investigaciones Cientificas CIC | Dias R.L.,Research Center y Desarrollo en Fermentaciones Industriales | Ruberto L.,University of Buenos Aires | Ruberto L.,CONICET | And 8 more authors.
International Biodeterioration and Biodegradation | Year: 2012

Under Antarctic conditions, bioremediation processes are highly limited. Although chronically contaminated soils seem to require no bioaugmentation, biostimulation proved to be beneficial although diverse results have been reported in relation to the type of nutrient source and the best experimental design. In this work we evaluated, in "on site" land plots, the effect that on the hydrocarbon removal and bacterial community structure of a fuel contaminated soil have an inorganic salts mixture, a complex organic matrix (fish meal) and a commercial product listed by the EPA. Also the effect of a surface active compound (Brij700) on biodegradation process was studied. Brij700 did not improve biodegradation in any of the studied conditions but induced relevant changes on bacterial community of soil amended with fish meal. Although fish meal significantly enhanced bacterial counts, this effect was unspecific, drastically changed the bacterial community structure and did not improve hydrocarbon removal. Salts amended systems evidenced a non significant decrease in contaminant concentration. Commercial product caused the higher reduction (49.4%, p < 0.05) of hydrocarbons compared with the control system after 45 d of treatment and cause the minor changes in bacterial community, constituting a promising alternative for some hydrocarbon-contaminated Antarctic soil restoration. © 2012 Elsevier Ltd.

Rojas N.L.,Research Center y Desarrollo en Fermentaciones Industriales | Voget C.E.,Research Center y Desarrollo en Fermentaciones Industriales | Hours R.A.,Research Center y Desarrollo en Fermentaciones Industriales | Cavalitto S.F.,Research Center y Desarrollo en Fermentaciones Industriales
Journal of Industrial Microbiology and Biotechnology | Year: 2011

Rhamnosidases are enzymes that catalyze the hydrolysis of terminal nonreducing L-rhamnose for the bioconversion of natural or synthetic rhamnosides. They are of great significance in the current biotechnological area, with applications in food and pharmaceutical industrial processes. In this study we isolated and characterized a novel alkaline rhamnosidase from Acrostalagmus luteo albus, an alkali-tolerant soil fungus from Argentina. We also present an efficient, simple, and inexpensive method for purifying the A. luteo albus rhamnosidase and describe the characteristics of the purified enzyme. In the presence of rhamnose as the sole carbon source, this fungus produces a rhamnosidase with a molecular weight of 109 kDa and a pI value of 4.6, as determined by SDS-PAGE and analytical isoelectric focusing, respectively. This enzyme was purified to homogeneity by chromatographic and electrophoretic techniques. Using p-nitrofenil-α-L-rhamnopiranoside as substrate, the enzyme activity showed pH and temperature optima of 8.0 and 55°C, respectively. The enzyme exhibited Michaelis-Menten kinetics, with K M and V max values of 3.38 mmol l -1 and 68.5 mmol l -1 min -1, respectively. Neither divalent cations such as Ca 2+, Mg 2+, Mn 2+, and Co 2+ nor reducing agents such as β-mercaptoethanol and dithiothreitol showed any effect on enzyme activity, whereas this activity was completely inhibited by Zn 2+ at a concentration of 0.2 mM. This enzyme showed the capacity to hydrolyze some natural rhamnoglucosides such as hesperidin, naringin and quercitrin under alkaline conditions. Based on these results, and mainly due to the high activity of the A. luteo albus rhamnosidase under alkaline conditions, this enzyme should be considered a potential new biocatalyst for industrial applications. © 2011 Society for Industrial Microbiology.

Discover hidden collaborations