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1.
Metallomics ; 10(8): 1078-1088, 2018 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-29999065

RESUMO

It has become increasingly apparent that the environmental microorganisms residing in uranium (U) enriched sites offer the possibility of understanding the biological mechanisms catalyzing the processes important for uranium bioremediation. Here, we present the results of uranium biomineralization over a wide pH range by a metal tolerant Serratia sp. strain OT II 7 isolated from the subsurface soil of a U ore deposit at Domiasiat in India. The Serratia cells actively expressed acid and alkaline phosphatase enzymes which hydrolyzed differential amounts of phosphate from an organophosphate substrate in the presence of uranium between pH 5 to 9. These cells precipitated ∼91% uranium from aqueous solutions supplemented with 1 mM uranyl nitrate at pH 5 within 120 h. More rapid precipitation was observed at pH 7 and 9 wherein the cells removed ∼93-94% of uranium from solutions containing 1 mM uranyl carbonate within 24 h. The aqueous uranyl speciation prevalent under the studied pH conditions influenced the localization of crystalline uranyl phosphate precipitates, which in turn, impacted the cell viability to a great extent. Furthermore, the cells tolerated up to ∼1.6 kGy 60Co gamma radiation and their uranium precipitation abilities at pH 5, 7 and 9 were uncompromised even after exposure to a high dose of ionizing radiation. Overall, this study establishes the ecological adaptation of a natural strain like Serratia in a uranium enriched environment and corroborates its contribution towards uranium immobilization in contaminated subsurfaces through the formation of stable uranyl phosphate minerals over a wide pH range.


Assuntos
Ácidos/farmacologia , Álcalis/farmacologia , Biodegradação Ambiental , Biomineralização , Poluentes Radioativos/farmacologia , Serratia/metabolismo , Urânio/metabolismo , Precipitação Química , Concentração de Íons de Hidrogênio , Fosfatos/metabolismo , Serratia/efeitos dos fármacos , Serratia/efeitos da radiação
2.
Appl Environ Microbiol ; 78(24): 8840-4, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23042169

RESUMO

The physiology of a newly recognized Serratia species, termed South African Caenorhabditis briggsae Isolate (SCBI), which is both a nematode mutualist and an insect pathogen, was investigated and compared to that of Serratia marcescens Db11, a broad-host-range pathogen. The two Serratia strains had comparable levels of virulence for Manduca sexta and similar cytotoxic activity patterns, but motility and lipase and hemolytic activities differed significantly between them.


Assuntos
Manduca/microbiologia , Serratia/fisiologia , Serratia/efeitos da radiação , Animais , Caenorhabditis/microbiologia , Hemólise/efeitos da radiação , Lipase/metabolismo , Locomoção/efeitos da radiação , Serratia/isolamento & purificação , Serratia/patogenicidade , Temperatura , Virulência
3.
Biotechnol Bioeng ; 109(8): 1937-46, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22422344

RESUMO

Aqueous wastes from nuclear fuel reprocessing present special problems of radiotoxicity of the active species. Cells of Serratia sp. were found previously to accumulate high levels of hydrogen uranyl phosphate (HUP) via the activity of a phosphatase enzyme. Uranium is of relatively low radiotoxicity whereas radionuclide fission products such as (90)Sr and (137)Cs are highly radiotoxic. These radionuclides can be co-crystallized, held within the bio-HUP "host" lattice on the bacterial cells and thereby removed from contaminated solution, depending on continued phosphatase activity. Radiostability tests using a commercial (60)Co γ-source showed that while cell viability and activity of purified phosphatase were lost within a few hours on irradiation, whole-cell phosphatase retained 80% of the initial activity, even after loss of cell culturability, which was increased to 100% by the incorporation of mercaptoethanol as an example radioprotectant, beyond an accumulated dose of >1.3 MGy. Using this co-crystallization approach (without mercaptoethanol) (137)Cs(+) and (85)Sr(2+) were removed from a simulated waste selectively against a 33-fold excess of Na(+).


Assuntos
Monoéster Fosfórico Hidrolases/metabolismo , Resíduos Radioativos , Radioisótopos/metabolismo , Serratia/enzimologia , Serratia/efeitos da radiação , Cristalização , Mercaptoetanol/metabolismo , Viabilidade Microbiana/efeitos da radiação , Protetores contra Radiação/metabolismo , Fatores de Tempo , Eliminação de Resíduos Líquidos/métodos , Gerenciamento de Resíduos/métodos
4.
J Occup Environ Hyg ; 4(5): 321-31, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17365506

RESUMO

The objective of this research was to study the factors that relate to the effectiveness of upper-room ultraviolet germicidal irradiation for inactivating airborne microorganisms. The work was conducted in a room-sized chamber designed and furnished for investigations of this nature. Nebulized Serratia marcescens, Bacillus subtilis spores, and vaccinia virus were used as test aerosols. Most data were collected from steady-state experiments comparing the number of viable organisms in the chamber air remaining with UV lamps turned on to the number with UV lamps turned off, but some decay experiments were conducted to compare the two methods. UV power level had a strong influence but was fully effective only in the presence of air mixing that produced vigorous vertical air currents. A conclusion of the study is that an upper-room ultraviolet installation is a complex system that requires careful integration of UV luminaires, UV power, and room ventilation arrangements.


Assuntos
Microbiologia do Ar , Desinfecção , Raios Ultravioleta , Bacillus subtilis/patogenicidade , Bacillus subtilis/efeitos da radiação , Ambiente Controlado , Serratia/patogenicidade , Serratia/efeitos da radiação , Ventilação
5.
Poult Sci ; 84(6): 955-8, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15971537

RESUMO

The effect of high-energy electron beam irradiation on the survival of Salmonella enterica serovar Typhimurium and psychrotrophic bacteria on commercial chicken breast meat was evaluated. Fresh chicken breast meat was purchased from a local poultry processor, inoculated with 8 log10 cfu/mL Salmonella, packaged in Styrofoam trays and over wrapped with a polyvinyl chloride film, and subjected to 0, 1, 2, or 3 kGy of irradiation. The packaged samples were stored at 4 degrees C and analyzed for Salmonella Typhimurium and psychrotrophic organisms at 0, 2, 4, 6, 8, 10, 12, and 14 d of storage. Direct plating and enrichment methods were used for S. Typhimurium analyses. The direct plating method revealed a 4 log reduction in Salmonella for chicken breasts inoculated and treated with 1, 2, or 3 kGy of irradiation. Psychrotrophic counts were conducted at 7 degrees C for 10 d and 25 degrees C for 5 d to determine the effect of incubation methods on the recovery of psychrotrophic organisms. The enrichment method resulted in the repair of injured Salmonella cells and an elevated Salmonella Typhimurium count for all irradiation dosages when compared with data reported for the direct plating method. In general, psychrotrophic counts increased as storage time increased. However, psychrotrophic counts decreased (P < 0.05) as the irradiation dosage increased.


Assuntos
Bactérias/efeitos da radiação , Galinhas , Irradiação de Alimentos/métodos , Microbiologia de Alimentos , Carne/microbiologia , Salmonella typhimurium/efeitos da radiação , Animais , Temperatura Baixa , Contagem de Colônia Microbiana , Relação Dose-Resposta à Radiação , Enterobacter cloacae/efeitos da radiação , Embalagem de Alimentos , Conservação de Alimentos , Congelamento , Hafnia alvei/efeitos da radiação , Klebsiella pneumoniae/efeitos da radiação , Micrococcus/efeitos da radiação , Pseudomonas fluorescens/efeitos da radiação , Serratia/efeitos da radiação , Fatores de Tempo
6.
J Clin Pharm Ther ; 19(4): 249-56, 1994 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-7989404

RESUMO

This study was undertaken to determine the effect of low-dose gamma irradiation on aseptically admixed total parenteral nutrition (TPN) solutions to which large inocula of three test bacterial species were added. Microbiological safety levels were quantified in terms of sterility assurance levels (SALs), indicating the probability of contamination occurring expressed as 10-n. The radiation sensitivity (D10 values) of test bacteria in TPN solutions inoculated with a series of bacteria recognized as common contaminants of these products, was determined. Attainable SALs of TPN solutions containing test bacteria were subsequently calculated from the D10 values. Results showed that a minimum absorbed radiation dose as low as 1.5 kGy improved the SAL of aseptically prepared TPN solutions from a probability value of 10(-3) to a value of less than 10(-8) for the microorganisms investigated. At an absorbed dose as high as 8.3 kGy, no measurable changes in amino acid, electrolyte, glucose and lipid components of the solutions were detected. These findings have important implications for the enhancement of microbiological safety levels of aseptically prepared intravenous fluids in general.


Assuntos
Alimentos Fortificados/microbiologia , Nutrição Parenteral Total/normas , Aminoácidos/metabolismo , Aminoácidos/efeitos da radiação , Contagem de Colônia Microbiana , Estabilidade de Medicamentos , Eletrólitos/metabolismo , Eletrólitos/efeitos da radiação , Enterobacter cloacae/efeitos da radiação , Alimentos Fortificados/efeitos da radiação , Raios gama , Glucose/metabolismo , Glucose/efeitos da radiação , Humanos , Concentração de Íons de Hidrogênio , Klebsiella pneumoniae/efeitos da radiação , Metabolismo dos Lipídeos , Lipídeos/efeitos da radiação , Serratia/efeitos da radiação , Soluções , Esterilização
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