Heavy metal tolerance (Cr, Ag and Hg) in bacteria isolated from sewage

Brazilian Journal of Microbiology

Agostinho A. De Lima E Silva²  Márcia A. Ribeiro De Carvalho²  Sérgio A. L De Souza²  Patrícia M. Teixeira Dias²  Renato G. Da Silva Filho²  Carmen S. De Meirelles Saramago²  Cleonice A. De Melo Bento²  Ernesto Hofer¹ 

[1] ,Universidade Federal do Estado do Rio de Janeiro Departamento de Microbiologia e Parasitologia Rio de Janeiro RJ ,Brasil

关键词: metal tolerance;    sewage;    pigment;    enzymatic inhibition;    antimicrobial resistance;   

DOI  :  10.1590/S1517-83822012000400047

来源: SciELO

【 摘 要 】

Samples of sewage from a university hospital and a chemistry technical school were analysed for the percentage of bacterial tolerance to chromium (Cr), silver (Ag) and mercury (Hg). Additionally, we investigated the effect of these metals on pigmentation and on some enzymatic activities of the metal tolerant strains isolated, as well as antimicrobial resistance in some metal tolerant Enterobacteriaceae strains. Tolerance to Cr was observed mainly in Gram positive bacteria while in the case of Ag and Hg the tolerant bacteria were predominately Gram negative. Hg was the metal for which the percentage of tolerance was significantly higher, especially in samples from the hospital sewage (4.1%). Mercury also had the most discernible effect on color of the colonies. Considering the effect of metals on the respiratory enzymes, one strain of Ag-tolerantBacillus sp. and one of Hg-tolerant P. aeruginosa were unable to produce oxidase in the presence of Ag and Hg, respectively, while the expression of gelatinase was largely inhibited in various Gram negative strains (66% by Cr). Drug resistance in Hg-tolerant Enterobacteriaceae strains isolated from the university hospital sewage was greater than 80%, with prevalence of multiple resistance, while the Ag-tolerant strains from the same source showed about 34% of resistance, with the predominance of mono-resistance. Our results showed that, despite the ability of metal tolerant strains to survive and grow in the presence of these elements, the interactions with these metals may result in metabolic or phisiological changes in this group of bacteria.

【 授权许可】

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