Time filter

Source Type

Nueve de Julio, Argentina

Villegas L.B.,CONICET | Villegas L.B.,North University of Santo Tomas de Aquino | Pereira C.E.,CONICET | Colin V.L.,CONICET | And 3 more authors.
International Biodeterioration and Biodegradation | Year: 2013

To help address conflicting opinions regarding the ability of chromate ions to use sulphate and phosphate membrane transporters to penetrate microbial cells, this work reports on an initial study related to the effect of these oxyanions on Cr(VI) removal by an actinobacterium, Streptomyces sp. MC1. Aspects related to growth and pleomorphism of this strain under Cr(VI) exposure are also presented. Although this strain was able to remove Cr(VI) from a liquid medium, significant decreases in both growth and filament branching were observed under metal exposure. The presence of sulphate and phosphate ions in the culture medium did not reverse the Cr(VI)-induced morphological transition. However, both ions mitigated the inhibitory effect of Cr(VI) on bacterial growth, and increased their removal from culture supernatants. Since total chromium concentration in the supernatant remained constant, this finding may indicate that sulphate and phosphate ions play a key role in the external reduction of Cr(VI) by Streptomyces sp. MC1, and that therefore Cr(VI) bioremoval could be optimized in terms of time and cost. © 2013 Elsevier Ltd.

Colin V.L.,CONICET | Colin V.L.,University San Pablo Tucuman | Villegas L.B.,CONICET | Villegas L.B.,North University of Santo Tomas de Aquino | And 2 more authors.
International Biodeterioration and Biodegradation | Year: 2012

Heavy metal pollution is one the most serious environmental problems facing our planet today, and immediate solutions are needed. Heavy metals such as copper (Cu) and chromium (Cr) play an important role as trace elements in biochemical reactions, but these metals are toxic at higher concentrations. In our region, mining and industrial activities have led to large-scale copper contamination in the environment. All organisms have homeostasis mechanisms for this metal, but when these controls fail or are exceeded several toxicological processes can develop.Problems involving Cr contamination are related to the fact that Argentina is an important world producer of leather. A chromium compound is used as a tanning agent, which has resulted in severe contamination near tanneries, with a mix of Cr(III) and Cr(VI). At present, the conventional technologies used to remove heavy metals from the environment involve physicochemical processes, which are costly and require large amounts of energy and specialized equipment. However, microbe-based removal is now considered to be an effective alternative method to the conventional processes and is receiving greater levels of interest for potential uses in bioremediation.This review discusses the toxic effects of Cu and Cr on the environment and on human health, as well as possible approaches for bioremediation of these metals using native microbes from our region. © 2011 Elsevier Ltd.

Alvarez A.,CONICET | Alvarez A.,National University of Tucuman | Catalano S.A.,CONICET | Catalano S.A.,Instituto Superior Of Entomologia Insue | And 2 more authors.
Molecular Phylogenetics and Evolution | Year: 2013

The genus Streptomyces comprises a group of bacteria species with high economic importance. Several of these species are employed at industrial scale for the production of useful compounds. Other characteristic found in different strains within this genus is their capability to tolerate high level of substances toxic for humans, heavy metals among them. Although several studies have been conducted in different species of the genus in order to disentangle the mechanisms associated to heavy metal resistance, little is known about how they have evolved along Streptomyces phylogeny. In this study we built the largest Streptomyces phylogeny generated up to date comprising six genes, 113 species of Streptomyces and 27 outgroups. The parsimony-based phylogenetic analysis indicated that (i) Streptomyces is monophyletic and (ii) it appears as sister clade of a group formed by Kitasatospora and Streptacidiphilus species, both genera also monophyletic. Streptomyces strains resistant to heavy metals are not confined to a single lineage but widespread along Streptomyces phylogeny. Our result in combination with genomic, physiological and biochemical data suggest that the resistance to heavy metals originated several times and by different mechanisms in Streptomyces history. © 2012 Elsevier Inc.

Cardozo M.L.,CONICET | Ordonez R.M.,CONICET | Zampini I.C.,CONICET | Cuello A.S.,CONICET | And 2 more authors.
Food Research International | Year: 2010

Fruits such as Prosopis pod have been food sources (patay, arrope, chicha or aloja) of inhabitants of arid and semi-arid lands in South America. The aims of the present study were determine some nutritional and functional properties as well as genotoxicity of flour obtained from Prosopis ripe pods that were submitted to different processing. Sucrose constituted the main sugar for flours obtained from Prosopis alba and Prosopis nigra. Decoctions and macerations showed around 2.9% and 1.4% of soluble proteins, respectively. The highest free phenolics, flavonoids and condensed tannins contents were observed in aqueous extractions with heating. None of the samples presented phytic acid levels high enough to constitute a nutritional problem. Antioxidant activity (AA) was evaluated by DPPH, ABTS and β-carotene bleaching assays. Results showed that the antioxidant potential was significantly higher in flour obtained from P. nigra pods than in that from P. alba pods, and it was also higher in aqueous extracts than in alcoholic ones. Data obtained suggests that compounds responsible for AA are thermostable; therefore, Prosopis flour might be capable of retaining a significant amount of antioxidant capacity after heating. Prosopis extracts did not show any mutagenic effect with and without metabolic activation. Prosopis flour proved to be a non conventional, novel and rich source of antioxidant compounds that could help to prevent pathologies associated with oxidative stress. © 2010.

Saez J.M.,CONICET | Benimeli C.S.,CONICET | Benimeli C.S.,North University of Santo Tomas de Aquino | Amoroso M.J.,CONICET | And 2 more authors.
Chemosphere | Year: 2012

Lindane (γ-HCH) is an organochlorine insecticide that has been widely used in developing countries. It is known to persist in the environment and can cause serious health problems. One of the strategies adopted to remove lindane from the environment is bioremediation using microorganisms. Immobilized cells present advantages over free suspended cells, like their high degradation efficiency and protection against toxins. The aims of this work were: (1) To evaluate the ability of Streptomyces strains immobilized in four different matrices to remove lindane, (2) To select the support with optimum lindane removal by pure cultures, (3) To assay the selected support with consortia and (4) To evaluate the reusability of the immobilized cells. Four Streptomyces sp. strains had previously shown their ability to grow in the presence of lindane. Lindane removal by microorganisms immobilized was significantly higher than in free cells. Specifically immobilized cells in cloth sachets showed an improvement of around 25% in lindane removal compared to the abiotic control. Three strains showed significantly higher microbial growth when they were entrapped in silicone tubes. Strains immobilized in PVA-alginate demonstrated lowest growth. Mixed cultures immobilized inside cloth sachets showed no significant enhancement compared to pure cultures, reaching a maximum removal of 81% after 96. h for consortium I, consisting of the four immobilized strains together. Nevertheless, the cells could be reused for two additional cycles of 96. h each, obtaining a maximum removal efficiency of 71.5% when each of the four strains was immobilized in a separate bag (consortium III). © 2012 Elsevier Ltd.

Discover hidden collaborations