Characterization of copper-resistant bacteria and bacterial communities from copper-polluted agricultural soils of central Chile

BMC Microbiology

Research Article

Michael Seeger¹  Guillermo Bravo¹  Luis A Rojas¹  Fabiola Altimira¹  Myriam González¹  Carolina Yáñez² 

[1] Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química and Center of Nanotechnology and Systems Biology, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso, Chile;Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química and Center of Nanotechnology and Systems Biology, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso, Chile;Instituto de Biología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, 1680, Valparaíso, Chile;

关键词: Copper-resistant bacteria;    copA;    Sphingomonas;    Stenotrophomonas;    Arthrobacter;    Bacterial communities;   

DOI  :  10.1186/1471-2180-12-193

 received in 2012-03-20, accepted in 2012-08-27,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundCopper mining has led to Cu pollution in agricultural soils. In this report, the effects of Cu pollution on bacterial communities of agricultural soils from Valparaiso region, central Chile, were studied. Denaturing gradient gel electrophoresis (DGGE) of the 16S rRNA genes was used for the characterization of bacterial communities from Cu-polluted and non-polluted soils. Cu-resistant bacterial strains were isolated from Cu-polluted soils and characterized.ResultsDGGE showed a similar high number of bands and banding pattern of the bacterial communities from Cu-polluted and non-polluted soils. The presence of copA genes encoding the multi-copper oxidase that confers Cu-resistance in bacteria was detected by PCR in metagenomic DNA from the three Cu-polluted soils, but not in the non-polluted soil. The number of Cu-tolerant heterotrophic cultivable bacteria was significantly higher in Cu-polluted soils than in the non-polluted soil. Ninety two Cu-resistant bacterial strains were isolated from three Cu-polluted agricultural soils. Five isolated strains showed high resistance to copper (MIC ranged from 3.1 to 4.7 mM) and also resistance to other heavy metals. 16S rRNA gene sequence analyses indicate that these isolates belong to the genera Sphingomonas, Stenotrophomonas and Arthrobacter. The Sphingomonas sp. strains O12, A32 and A55 and Stenotrophomonas sp. C21 possess plasmids containing the Cu-resistance copA genes. Arthrobacter sp. O4 possesses the copA gene, but plasmids were not detected in this strain. The amino acid sequences of CopA from Sphingomonas isolates (O12, A32 and A55), Stenotrophomonas strain (C21) and Arthrobacter strain (O4) are closely related to CopA from Sphingomonas, Stenotrophomonas and Arthrobacter strains, respectively.ConclusionsThis study suggests that bacterial communities of agricultural soils from central Chile exposed to long-term Cu-pollution have been adapted by acquiring Cu genetic determinants. Five bacterial isolates showed high copper resistance and additional resistance to other heavy metals. Detection of copA gene in plasmids of four Cu-resistant isolates indicates that mobile genetic elements are involved in the spreading of Cu genetic determinants in polluted environments.

【 授权许可】

Unknown   
© Altimira et al.; licensee BioMed Central Ltd. 2012. This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.