Ochrobactrum sp. MPV1 from a dump of roasted pyrites can be exploited as bacterial catalyst for the biogenesis of selenium and tellurium nanoparticles

Abstract Background Bacteria have developed different mechanisms for the transformation of metalloid oxyanions to non-toxic chemical forms. A number of bacterial isolates so far obtained in axenic culture has shown the ability to bioreduce selenite and tellurite to the elemental state in different conditions along with the formation of nanoparticles—both inside and outside the cells—characterized by a variety of morphological features. This reductive process can be considered of major importance for two reasons: firstly, toxic and soluble (i.e. bioavailable) compounds such as selenite and tellurite are converted to a less toxic chemical forms (i.e. zero valent state); secondly, chalcogen nanoparticles have attracted great interest due to their photoelectric and semiconducting properties. In addition, their exploitation as antimicrobial agents is currently becoming an area of intensive research in medical sciences. Results In the present study, the bacterial strain Ochrobactrum sp. MPV1, isolated from a dump of roasted arsenopyrites as residues of a formerly sulfuric acid production near Scarlino (Tuscany, Italy) was analyzed for its capability of efficaciously bioreducing the chalcogen oxyanions selenite (SeO3 2−) and tellurite (TeO3 2−) to their respective elemental forms (Se0 and Te0) in aerobic conditions, with generation of Se- and Te-nanoparticles (Se- and TeNPs). The isolate could bioconvert 2 mM SeO3 2− and 0.5 mM TeO3 2− to the corresponding Se0 and Te0 in 48 and 120 h, respectively. The intracellular accumulation of nanomaterials was demonstrated through electron microscopy. Moreover, several analyses were performed to shed light on the mechanisms involved in SeO3 2− and TeO3 2− bioreduction to their elemental states. Results obtained suggested that these oxyanions are bioconverted through two different mechanisms in Ochrobactrum sp. MPV1. Glutathione (GSH) seemed to play a key role in SeO3 2− bioreduction, while TeO3 2− bioconversion could be ascribed to the catalytic activity of intracellular NADH-dependent oxidoreductases. The organic coating surrounding biogenic Se- and TeNPs was also characterized through Fourier-transform infrared spectroscopy. This analysis revealed interesting differences among the NPs produced by Ochrobactrum sp. MPV1 and suggested a possible different role of phospholipids and proteins in both biosynthesis and stabilization of such chalcogen-NPs. Conclusions In conclusion, Ochrobactrum sp. MPV1 has demonstrated to be an ideal candidate for the bioconversion of toxic oxyanions such as selenite and tellurite to their respective elemental forms, producing intracellular Se- and TeNPs possibly exploitable in biomedical and industrial applications

In vitro propagation and germplasm conservation of wild orchids from South America

Orchids are an important part of plant biodiversity on this planet due to their high variability among species and their habitats. South America represents more than thirty percent of all known orchid species, Colombia, Ecuador, Brazil, Peru, and Bolivia being among the richest countries in the world in terms of orchid biodiversity. Nevertheless, concerning the orchid conservation status, in Colombia precisely orchids occupy the unlucky first place as the plant family with the highest number of threatened species. There is a similar situation in the rest of the South American countries. The two main threats to orchid survival are both anthropogenic: the first one is deforestation, and the second largest threat to orchids is collection from the wild. One desirable action to safeguard these endangered species is to develop procedures that make possible their massive propagation, which would provide material for both environmental restoration and commercial purposes avoiding extractions from nature. Likewise, the development of systems that allow the ex situ conservation of orchid germplasm is imperative. This chapter reviews the progresses of different in vitro approaches for orchid propagation and germplasm conservation, safeguarding the genetic biodiversity of these species. Several study cases are presented and described to exemplify the protocols developed in the Botanical Institute of Northeast (UNNE-CONICET) for propagating and long-term storing the germplasm of wild orchids from Argentina (Cattleya lundii, Cohniella cepula, C. jonesiana, Gomesa bifolia, Aa achalensis, Cyrtopodium brandonianum, C. hatschbachii, Habenaria bractescens). Moreover, it has been attempted to put together most of the available literature on in vitro propagation and germplasm conservation for South American orchids using different explants and procedures. There are researches of good scientific quality that even cover critical insights into the physiology and factors affecting growth and development as well as storage of several orchid materials. Moreover, studies are still necessary to cover a major number of South American species as well as the use of selected material (clonal) for both propagation and conservation approaches.Fil: Dolce, Natalia Raquel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Medina, Ricardo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Terada, Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: González Arnao, María Teresa. Universidad Veracruzana; MéxicoFil: Flachsland, Eduardo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; Argentin

Manipulation of Agricultural Habitats to Improve Conservation Biological Control in South America

International audienceStable and diversified agroecosystems provide farmers with important ecosystem services, which are unfortunately being lost at an alarming rate under the current conventional agriculture framework. Nevertheless, this concern can be tackled by using ecological intensification as an alternative strategy to recuperate ecosystem services (e.g., biological control of pests). To this end, the manipulation of agricultural habitats to enhance natural enemy conservation has been widely explored and reported in Western Europe and North America, whereas in other parts of the world, the investigation of such topic is lagging behind (e.g., South America). In this forum, we gathered published and unpublished information on the different ecological habitat management strategies that have been implemented in South America and their effects on pest control. Additionally, we identify the various challenges and analyze the outlook for the science of conservation biological control in South America. More specifically, we reviewed how different agricultural practices and habitat manipulation in South America have influenced pest management through natural enemy conservation. The main habitat manipulations reported include plant diversification (intercropping, insectary plants, agroforestry), conservation and management of non-crop vegetation, and application of artificial foods. Overall, we noticed that there is a significant discrepancy in the amount of research on conservation biological control among South American countries, and we found that, although intercropping, polycultures, and crop rotation have been reported in agroecosystems since pre-Inca times, more systematic studies are required to evaluate the true effects of habitat management to implement conservation biological control for pest control in South America