1,721,007 research outputs found
Selenite biotransformation by rhizospheric bacterial strains of potential use in environmental clean-up processes
No full textSoil bacterial strains have been demonstrated to be capable of detoxifying the highly bioavailable selenium oxyanion selenite (Se IV) by reducing it under aerobic conditions to the non toxic form elemental selenium. The perspective of a possible exploitation of these bacterial isolates for bioremediation purposes is here discussed
Bonifica biologica di acque sotterranee mediante processi di trattamento in situ
No full textLa bonifica biologica delle acque di falda mediante trattamenti in situ consiste nell'applicazione di processi ed apparati tecnologici volti ad esaltare lo sviluppo di microrganismi indigeni ovvero a controllare l'attività metabolica di ceppi microbici deliberatamente immessi nella matrice ambientale da trattare, al fine di incrementare la biodegradazione di contaminanti organici presenti nella zona di saturazione. Vengono qui analizzati i principali fattori che influenzano l'efficacia degli interventi di decontaminazione delle acque sotterranee
Rhizosphere-induced selenium precipitation for possible applications in phytoremediation of Se polluted effluents
No full textTwo bacterial isolates were obtained in axenic culture from the rhizosphere soil of Astragalus bisulcatus, a legume able to hyperaccumulate selenium. Both strains resulted of particular interest for their high resistance to the toxic oxyanion SeO3(2-) (selenite, Se(IV)). On the basis of molecular and biochemical analyses, these two isolates were attributed to the species Bacillus mycoides and Stenotrophomonas maltophilia, respectively. Their capability in axenic culture to precipitate the soluble, bioavailable and highly toxic selenium form selenite to insoluble and relatively non-toxic Se(0) (elemental selenium) was evaluated in defined medium added with 0.2 or 0.5 mM Se(IV). Both strains showed to completely reduce 0.2 mM selenite in 120 h, while 0.5 mM Se(IV) was reduced up to 67% of the initial concentration by B. mycoides and to about 50% by S. maltophilia in 48 h. Together in a dual consortium, B. mycoides and S. maltophilia increased the kinetics of selenite reduction, thus improving the efficiency of the process. A model system for selenium rhizofiltration based on plant-rhizobacteria interactions has been proposed
Selenite precipitation by a strain of Bacillus sp. in a sequencing batch system. Potential application for wastewater treatment
No full textA bacterial isolate related to the genus Bacillus sp., resistant to selenite (SeIV) up to 25 mM in the growth medium, was isolated from the rhizospheric soil of a selenium hyperaccumulator plant, namely the legume Astragalus bisulcatus
Bonifica biologica di suoli contaminati
No full textViene illustrata la biodegradazione microbica stimolata dalla rizosfera quale metodologia di intervento per l'abbattimento di contaminanti organici in terreni inquinati, sfruttando l'attività metabolica dei microorganismi che colonizzano la porzione di suolo posta all'intorno delle radici delle essenze vegetali di copertura
Selenite precipitation by a rhizospheric strain of Stenotrophomonas sp. isolated from the root system of Astragalus bisulcatus: a biotechnological perspective
No full textA bacterial strain (SeITE02), related to the species Stenotrophomonas maltophilia and resistant to selenite (SeIV) up to 50 mM in the growth medium, was isolated from rhizospheric soil of a selenium hyperaccumulator plant, the legume Astragalus bisulcatus. The influence of SeIV on the active growth of this Se-tolerant bacterial strain has been investigated in oxic conditions, along with the isolate's ability to reduce selenite to elemental selenium (Se 0). Interestingly, concentrations of 0.5 mM SeIV were wholly reduced by strain SeITE02 in liquid culture within 52 h. Moreover, 87% of SeIV added to the growth medium at the initial concentration of 2.0 mM underwent again reduction in 120 h. Actually, a selenite-mediated induction of a sort of adaptive response to detrimental SeIV effects magnified the efficiency of SeITE02 in reducing this toxic oxyanion. Furthermore, the SeIV influence on cell morphology of strain SeITE02 was evidenced by phase-contrast and electron microscopy analyses. In particular, transmission electron microscopy (TEM)-energy-dispersive X-ray (EDX) analysis of S. maltophilia strain SeITE02, grown in presence of SeIV, showed electron-dense Se0 granules either in the cell cytoplasm or in the extracellular space. Therefore, the capability of strain SeITE02 to quickly reduce soluble and harmful SeIV to insoluble and unavailable Se0 may be looked at as a promising exploitable option for the setup of low-cost biological treatments tailored to manage contamination in selenium-laden effluents. © 2004 Elsevier Ltd. All rights reserved
Incidenza di fattori ambientali, edafici ed ecologici sull'attività dei microorganismi responsabili dei processi di bonifica biologica di siti contaminati
No full textSi tratta di una diffusa trattazione dei fattori condizionanti l'attività dei microorganismi del suolo, al fine di individuare le condizioni operative ottimali per l'efficace applicazione delle procedure di bonifica biologica in siti interessati da contaminazione di composti organici tossici
Microbial transformation of organic to inorganic lead: Putative involvement of a soil bacterial community
No full textThe link between composition of the telluric microbial community and microbial processes responsable for the transformation of tetraethyl lead in soil are described and discussed here
Reduction of selenite to elemental selenium by a bacterial strain of Stenotrophomonas sp. isolated from the rhizosphere of the hyperaccumulator legume Astralagus bisulcatus
No full textA bacterial strain belonging to the genus Stenotrophomonas sp. isolated from the rhizosphere of the Se hyperaccumulator plant Astragalus bisulcatus is described. The isolate has been demonstrated to be able to reduce in aerobic conditions the very toxic oxyanion selenite to the non toxic elemental selenium
Biodiversity amongst cultivable polycyclic aromatic hydrocarbon-transforming bacteria isolated from an abandoned industrial site
No full textThe characterisation of a microbial community of a polycyclic aromatic hydrocarbons (PAHs) contaminated site (formerly Carbochimica, Trento, Italy) was carried out. A preliminary evaluation of the heterogeneity and the metabolic activity of the microbial community were attempted by denaturing gradient gel electrophoresis (DGGE) and reverse transcriptase-denaturing gel electrophoresis (RT-DGGE). The presence of a heterogeneous and metabolically active microbial community was found. To evaluate the PAH-transforming potential of the soil bacterial community, enrichment cultures were set up. Taxonomically diverse bacteria, showing different biochemical PAH-transforming pathways were obtained. Some of the isolates showed not nah-homologous PAH-transforming genotypes
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