Papers by Keyword: Pseudomonas

Abstract: The paper deals with laboratory testing of PAHs biodegradation in samples of sleeper subsoil via two chosen microorganisms, bacteria Pseudomonas monteilii and Rhodococcus degradans. The obtained results show that the pure bacterial culture R. degradans removed 46 % PAHs in 28 days. Bacterium P. monteilii was far more successful in degrading PAHs, it managed to remove 74 % PAHs. The worst result was from the mixture of both bacteria which degraded only 34 % PAHs.

Abstract: Dibenzothiophene (DBT) may seriously pollute the environment with its mutagenicity, teratogenicity and carcinogenicity. And it is recalcitrant to be degraded by microorganisms due to its low bioavailability and high hydrophobicity. In this paper, the five parameters, namely, initial concentration, temperature, pH, agitation rate and inoculum size were experimented and studied by the isolated Pseudomonas sp. LKY-5 for degradation processes. The results shown that the initial concentration of 100 mg/L, temperature of 30°C, pH of 7.5, agitation rate of 160 rpm, inoculum size of 10 % were optimal for the biodegradation of dibenzothiophene.

Abstract: The antimicrobial effects of silver nanoparticles (Ag-NPs) are well known, but Ag-NPs are known to aggregate in medium of high salt content and lose their antibacterial activity. Graphene-based silver nanoparticles (Ag NPs-GE) materials can form stable dispersion in the aqueous solution. This study explores the antimicrobial effects of Ag NPs-GE in pathogenic bacteria, Pseudomonas aeruginosa. The antimicrobial activity of Ag NPs-GE was investigated in Luria-Bertani (LB) medium on solid agar plates and liquid system supplement with various concentrations of Ag NPs-GE. The Ag NPs-GE were shown to be an effective bactericide.

Abstract: The aim of this research was the selection of bacterial strains resistant to mercury, as well as to demonstrate their capacity to reduce mercury in solution when they are inoculated in pure and mixed cultures. Samples of soil from informal mining gold sites in Peru were collected and fifteen mercury resistant bacteria were isolated. Strains RM6, RM7, RM9, RM11, RM12 and RM13 were selected for their capacity to reduce mercury in solution. The six bacterial strains belong to the genus Pseudomonas. Inoculated in pure cultures, these strains reduce mercury in solution although in different percentages: RM9, RM11 an RM12 reduce 93% to 97% of the mercury, while strains RM6, RM7 y RM13 reduce 80% to 85%. The consortium of all six bacterial strains showed a mercury reduction of 84%. Approximately 91% of mercury in solution was reduced in 1 hour and this reaction was not associated to bacterial growth. Using specific primers, the merA gene was amplified from genomic DNA of the bacterial strains, which would suggest the activity of the mer operon as a mechanism of mercury resistance. Due to their ability to reduce mercury in solution, it is advisable to carry out more research on the selected strains since they could be useful in future bioremediation processes.

Abstract: Cyanogenic Chromobacterium violaceum, Pseudomonas fluorescens, and P. plecoglossicida were able to mobilize silver, gold and platinum when grown in the presence of various metal-containing solids such as powdered platinum, platinum-containing automobile catalytic converters, powdered silver, or gold-containing electronic scrap. Five percent of silver was mobilized from powdered jewelry scrap as dicyanoargentate after one day, although 96% was mobilized when non-biological cyanide leaching was applied. Dicyanoargentate proved to inhibit growth at concentrations >20 mg/L. Gold was microbially solubilized from electronic scrap (shredded printed circuit boards). Maximum dicyanoaurate concentration corresponded to a 68.5% dissolution of the total gold added. Additionally, cyanide-complexed copper was detected during treatment of electronic scrap due to its high copper content of approximately 100 g/kg scrap. Small amounts of platinum were mobilized from pure platinum powder after 10 days. The process proved to be very slow. In summary, all findings demonstrate the potential of microbial mobilization of metals as cyanide complex from solid materials and represent a novel type of microbial metal mobilization which might find industrial application.