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Roosa S.,University of Mons | Wauven C.V.,Institute Of Recherches Microbiologiques Jmw | Billon G.,Lille University of Science and Technology | Matthijs S.,Institute Of Recherches Microbiologiques Jmw | And 2 more authors.
Research in Microbiology | Year: 2014

Pseudomonas bacteria are ubiquitous Gram-negative and aerobic microorganisms that are known to harbor metal resistance mechanisms such as efflux pumps and intracellular redox enzymes. Specific Pseudomonas bacteria have been quantified in some metal-contaminated environments, but the entire Pseudomonas population has been poorly investigated under these conditions, and the link with metal bioavailability was not previously examined. In the present study, quantitative PCR and cell cultivation were used to monitor and characterize the Pseudomonas population at 4 different sediment sites contaminated with various levels of metals. At the same time, total metals and metal bioavailability (as estimated using an HCl 1. m extraction) were measured. It was found that the total level of Pseudomonas, as determined by qPCR using two different genes (oprI and the 16S rRNA gene), was positively and significantly correlated with total and HCl-extractable Cu, Co, Ni, Pb and Zn, with high correlation coefficients (>0.8). Metal-contaminated sediments featured isolates of the Pseudomonas putida, Pseudomonas fluorescens, Pseudomonas lutea and Pseudomonas aeruginosa groups, with other bacterial genera such as Mycobacterium, Klebsiella and Methylobacterium. It is concluded that Pseudomonas bacteria do proliferate in metal-contaminated sediments, but are still part of a complex community. © 2014 Institut Pasteur. Source

Kabagale A.C.,Free University of Colombia | Kabagale A.C.,University of Lubumbashi | Cornu B.,Institute Of Recherches Microbiologiques Jmw | van Vliet F.,Institute Of Recherches Microbiologiques Jmw | And 7 more authors.
Plant and Soil | Year: 2010

Haumaniastrum katangense and Crepidorhopalon tenuis are two cuprophytes characteristic of the Katangan Copper Belt flora. We have studied the endophytic bacteria of H. katangense and C. tenuis as a first step to evaluate their potential contribution to plant adaptation to copper excess. Although their number varied considerably from sample to sample, culturable bacteria were found in roots and shoots of most plants. More than 800 isolates were screened for each plant species. Identification of isolates based on the sequence of the 16S rRNA gene, allocated them to 31 taxonomic units, belonging to 17 genera, mainly Proteobacteria. A great proportion of the bacteria were cupro-resistant and often resistant to other metals, especially zinc and cobalt, as well as nickel for the Methylobacterium isolates. Direct PCR amplification of the polymorphic bacterial internal transcribed spacer (ITS) from the plants' organs DNA revealed a more diverse endophytic community, with more Gram+, among which a Rubrobacteridae that was never found associated with plants before. This work represents the first study of endophytes in Katangan cuprophytes. © 2010 Springer Science+Business Media B.V. Source

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