title: Metal resistance mechanisms in Gram-negative bacteria and their potential to remove Hg in the presence of other metals.
abstract: Contamination of the environment by heavy metals has been increasing in recent years due to industrial activities. Thus research involving microorganisms capable of surviving in multi-contaminated environments is extremely important. The objectives of the present study were to evaluate the removal of mercury alone and in the presence of cadmium, nickel and lead by four mercury-resistant microorganisms; estimate the removal of Cd, Ni and Pb; understand the mechanisms involved (reduction, siderophores, biofilms, biosorption and bioaccumulation) in the metal resistance of the isolate Pseudomonas sp. B50D; and determine the capacity of Pseudomonas sp. B50D in removing Hg, Cd, Ni and Pb from an industrial effluent. It was shown that the four isolates evaluated were capable of removing from 62% to 95% of mercury from a culture medium with no addition of other metals. The isolate Pseudomonas sp. B50D showed the best performance in the removal of mercury when evaluated concomitantly with other metals. This isolate was capable of removing 75% of Hg in the presence of Cd and 91% in the presence of Ni and Pb. With respect to the other metals it removed 60%, 15% and 85% of Cd, Ni and Pb, respectively. In tests with effluent, the isolate Pseudomonas sp. B50D removed 85% of Hg but did not remove the other metals. This isolate presented reduction, biosorption, biofilm production and siderophore production as its metal resistance mechanisms. Pseudomonas sp. B50D was thus a candidate with potential for application in the bioremediation of effluents with complex metal contaminations.
authors.affiliation: Fuels and Biofuels Biodeterioration Laboratory (LAB-BIO), Departament of Microbiology, Immunology and Parasitology - Institute of Health Science, Federal University of Rio Grande do Sul, 500 Sarmento Leite St, 90050-170 Porto Alegre, RS, Brazil. Electronic address: patricia.giovanella@hotmail.com.
authors.forename: Patricia
authors.initials: P
authors.lastname: Giovanella
authors.affiliation: Research Center for Chemistry, Biology and Agriculture (CPQBA), University of Campinas (UNICAMP), 999 Alexandre Cazelatto St, Caixa Postal: 6171 Betel, 13081-970 Paulínia, SP, Brazil.
authors.forename: Lucélia
authors.initials: L
authors.lastname: Cabral
authors.affiliation: Fuels and Biofuels Biodeterioration Laboratory (LAB-BIO), Departament of Microbiology, Immunology and Parasitology - Institute of Health Science, Federal University of Rio Grande do Sul, 500 Sarmento Leite St, 90050-170 Porto Alegre, RS, Brazil.
authors.forename: Alexandre Pereira
authors.initials: AP
authors.lastname: Costa
authors.affiliation: Departament of Soil Science, Federal University of Rio Grande do Sul, 7712 Bento Gonçalves Ave, 91540-000 Porto Alegre RS, Brazil.
authors.forename: Flávio Anastácio
authors.initials: FA
authors.lastname: de Oliveira Camargo
authors.affiliation: Departament of Soil Science, Federal University of Rio Grande do Sul, 7712 Bento Gonçalves Ave, 91540-000 Porto Alegre RS, Brazil.
authors.forename: Clesio
authors.initials: C
authors.lastname: Gianello
authors.affiliation: Fuels and Biofuels Biodeterioration Laboratory (LAB-BIO), Departament of Microbiology, Immunology and Parasitology - Institute of Health Science, Federal University of Rio Grande do Sul, 500 Sarmento Leite St, 90050-170 Porto Alegre, RS, Brazil.
authors.forename: Fátima Menezes
authors.initials: FM
authors.lastname: Bento
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D042481:Alcaligenes faecalis / Q000302:isolation & purification / Q000378:metabolism; D001673:Biodegradation, Environmental; D018441:Biofilms; D002104:Cadmium / Q000378:metabolism; D007220:Industrial Waste; D007854:Lead / Q000378:metabolism; D008628:Mercury / Q000378:metabolism*; D019216:Metals, Heavy / Q000302:isolation & purification; D009532:Nickel / Q000378:metabolism; D011549:Pseudomonas / Q000302:isolation & purification / Q000378:metabolism*; D016958:Pseudomonas putida / Q000302:isolation & purification / Q000378:metabolism*; D017262:Siderophores / Q000378:metabolism
chemical_list: D007220:Industrial Waste; D019216:Metals, Heavy; D017262:Siderophores; D002104:Cadmium; D007854:Lead; D009532:Nickel; D008628:Mercury
keywords: Biofilm; Bioremediation; Biosorption; Mercury; Multi-metal resistant bacteria; Siderophores