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GFP-tagged multimetal-tolerant bacteria and their detection in the rhizosphere of white mustard.

Piotrowska-Seget Z, Beściak G, Bernaś T, Kozdrój J - Ann. Microbiol. (2011)

Bottom Line: In this study, soil of a metal-mine wasteland was analyzed for the presence of metal-tolerant bacterial isolates, and the tolerance patterns of the isolated strains for a number of heavy metals and antibiotics were compared.From among the successfully tagged isolates, we used the transconjugant Pseudomonas putida G25 (pPROBE-NT) to inoculate white mustard seedlings.Despite a significant decrease in transconjugant abundance in the rhizosphere, the gfp-tagged cells survived on the root surfaces at a level previously reported for root colonisers.

View Article: PubMed Central - PubMed

ABSTRACT
The introduction of rhizobacteria that tolerate heavy metals is a promising approach to support plants involved in phytoextraction and phytostabilisation. In this study, soil of a metal-mine wasteland was analyzed for the presence of metal-tolerant bacterial isolates, and the tolerance patterns of the isolated strains for a number of heavy metals and antibiotics were compared. Several of the multimetal-tolerant strains were tagged with a broad host range reporter plasmid (i.e. pPROBE-NT) bearing a green fluorescent protein marker gene (gfp). Overall, the metal-tolerant isolates were predominately Gram-negative bacteria. Most of the strains showed a tolerance to five metals (Zn, Cu, Ni, Pb and Cd), but with differing tolerance patterns. From among the successfully tagged isolates, we used the transconjugant Pseudomonas putida G25 (pPROBE-NT) to inoculate white mustard seedlings. Despite a significant decrease in transconjugant abundance in the rhizosphere, the gfp-tagged cells survived on the root surfaces at a level previously reported for root colonisers.

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Related in: MedlinePlus

Dendrogram representing similarities of metal and antibiotic tolerance patterns of different bacterial strains isolated from soil of a metal-mine wasteland. Ao Arthrobacter oxydans, Ba Brevibacterium acetylicum, Bam Bacillus amyloliquefaciens, Bc Bacillus cereus, Bs Bacillus sphaericus, Ca Comamonas acidovorans, Cd Citrobacter diversus, IGB2, IGB8 isolates GB2 and GB8, Kp Klebsiella pneumoniae, Pa Pantoea agglomerans, Pp Pseudomonas putida
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Fig1: Dendrogram representing similarities of metal and antibiotic tolerance patterns of different bacterial strains isolated from soil of a metal-mine wasteland. Ao Arthrobacter oxydans, Ba Brevibacterium acetylicum, Bam Bacillus amyloliquefaciens, Bc Bacillus cereus, Bs Bacillus sphaericus, Ca Comamonas acidovorans, Cd Citrobacter diversus, IGB2, IGB8 isolates GB2 and GB8, Kp Klebsiella pneumoniae, Pa Pantoea agglomerans, Pp Pseudomonas putida

Mentions: In terms of antibiotic tolerance, only five of the identified species (i.e. Bacillus cereus GB1, Arthrobacter oxydans, Citrobacter diversus, Brevibacterium acetylicum and Pseudomonas putida G17) showed a tolerance to Tc, Kn and/or Ap. A similar number of strains, however, all belonging to one species, namely P. putida (i.e. G15, G16, G18, G24 and G25), tolerated only Ap. By contrast, four strains (i.e. Bacillus sphaericus GB3, B. cereus GB7, B. amyloliquefaciens and the isolate IGB 8) were sensitive to all three antibiotics (Table 1). Antibiotic tolerance often accompanies an increased resistance to heavy metals among different bacteria isolated from sites exposed to high pollution and/or containing material rich in the metals (Berg et al. 2005; Stepanauskas et al. 2005; Baker-Austin et al. 2006). This situation results from the co-transfer of antibiotic resistance genes and those of metal resistance on the same plasmid under selective conditions (Foster 1983; Baker-Austin et al. 2006). However, the ecological role of this association for bacterial strains occupying a severe habitat is not fully understood. Presumably, the extra feature of antibiotic resistance increases their survival success during the competition for available niches when in the presence of compounds acting as antimicrobials and signal molecules. As a result, respective strains of bacteria may differ in their tolerance profiles, which may in turn affect their survival (Alonso et al. 2001; Hibbing et al. 2010). Our cluster analysis of the metal and antibiotic tolerance patterns of all the bacterial strains showed that they grouped into two major clusters (Fig. 1). The first composite cluster included only strains of Pseudomonas putida, with the one exception being Comamonas acidovorans. However, the second major cluster was composed of two subclusters, with one comprising all of the Gram-positive strains, and the second consisting of Gram-negative strains of Pantoea agglomerans (clustering together) and Klebsiella pneumoniae grouping with Citrobacter diversus separately (Fig. 1). This clustering pattern shows that the separation of the P. putida group may have been associated with the possession of a common mechanism(s) of metal tolerance that is chromosomally encoded (Cánovas et al. 2003). In contrast, the Gram-positive strains with their thicker cell envelopes react to biocides differently. Their clustering might be, at least in part, due to the presence of a common plasmid carrying genes for multimetal and drug resistance (Kamala-Kanan and Kui Jae 2008). Bacterial species such as P. agglomerans, K. pneumoniae and C. diversus belong to the same family of Enterobacteriaceae. Therefore, they formed the separate cluster towards the other Gram-negative group of P. putida in this study. In addition, their likeness supports the fact the multidrug resistance (mar) operon is widespread among enteric bacteria (Cohen et al. 1993). However, closer clustering of these bacteria with the Gram-positive group may be explained by their similar ability for protection against the biocides, due to the role of the cell envelopes (i.e. glycocalyx and thick cell wall, respectively). Regarding the cluster of K. pneumoniae and C. diversus, their likeness may have resulted from the presence of the same phosphatase-mediated metal accumulation process involved in the detoxification of the bacteria (Macaskie et al. 1994).Fig. 1


GFP-tagged multimetal-tolerant bacteria and their detection in the rhizosphere of white mustard.

Piotrowska-Seget Z, Beściak G, Bernaś T, Kozdrój J - Ann. Microbiol. (2011)

Dendrogram representing similarities of metal and antibiotic tolerance patterns of different bacterial strains isolated from soil of a metal-mine wasteland. Ao Arthrobacter oxydans, Ba Brevibacterium acetylicum, Bam Bacillus amyloliquefaciens, Bc Bacillus cereus, Bs Bacillus sphaericus, Ca Comamonas acidovorans, Cd Citrobacter diversus, IGB2, IGB8 isolates GB2 and GB8, Kp Klebsiella pneumoniae, Pa Pantoea agglomerans, Pp Pseudomonas putida
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3351603&req=5

Fig1: Dendrogram representing similarities of metal and antibiotic tolerance patterns of different bacterial strains isolated from soil of a metal-mine wasteland. Ao Arthrobacter oxydans, Ba Brevibacterium acetylicum, Bam Bacillus amyloliquefaciens, Bc Bacillus cereus, Bs Bacillus sphaericus, Ca Comamonas acidovorans, Cd Citrobacter diversus, IGB2, IGB8 isolates GB2 and GB8, Kp Klebsiella pneumoniae, Pa Pantoea agglomerans, Pp Pseudomonas putida
Mentions: In terms of antibiotic tolerance, only five of the identified species (i.e. Bacillus cereus GB1, Arthrobacter oxydans, Citrobacter diversus, Brevibacterium acetylicum and Pseudomonas putida G17) showed a tolerance to Tc, Kn and/or Ap. A similar number of strains, however, all belonging to one species, namely P. putida (i.e. G15, G16, G18, G24 and G25), tolerated only Ap. By contrast, four strains (i.e. Bacillus sphaericus GB3, B. cereus GB7, B. amyloliquefaciens and the isolate IGB 8) were sensitive to all three antibiotics (Table 1). Antibiotic tolerance often accompanies an increased resistance to heavy metals among different bacteria isolated from sites exposed to high pollution and/or containing material rich in the metals (Berg et al. 2005; Stepanauskas et al. 2005; Baker-Austin et al. 2006). This situation results from the co-transfer of antibiotic resistance genes and those of metal resistance on the same plasmid under selective conditions (Foster 1983; Baker-Austin et al. 2006). However, the ecological role of this association for bacterial strains occupying a severe habitat is not fully understood. Presumably, the extra feature of antibiotic resistance increases their survival success during the competition for available niches when in the presence of compounds acting as antimicrobials and signal molecules. As a result, respective strains of bacteria may differ in their tolerance profiles, which may in turn affect their survival (Alonso et al. 2001; Hibbing et al. 2010). Our cluster analysis of the metal and antibiotic tolerance patterns of all the bacterial strains showed that they grouped into two major clusters (Fig. 1). The first composite cluster included only strains of Pseudomonas putida, with the one exception being Comamonas acidovorans. However, the second major cluster was composed of two subclusters, with one comprising all of the Gram-positive strains, and the second consisting of Gram-negative strains of Pantoea agglomerans (clustering together) and Klebsiella pneumoniae grouping with Citrobacter diversus separately (Fig. 1). This clustering pattern shows that the separation of the P. putida group may have been associated with the possession of a common mechanism(s) of metal tolerance that is chromosomally encoded (Cánovas et al. 2003). In contrast, the Gram-positive strains with their thicker cell envelopes react to biocides differently. Their clustering might be, at least in part, due to the presence of a common plasmid carrying genes for multimetal and drug resistance (Kamala-Kanan and Kui Jae 2008). Bacterial species such as P. agglomerans, K. pneumoniae and C. diversus belong to the same family of Enterobacteriaceae. Therefore, they formed the separate cluster towards the other Gram-negative group of P. putida in this study. In addition, their likeness supports the fact the multidrug resistance (mar) operon is widespread among enteric bacteria (Cohen et al. 1993). However, closer clustering of these bacteria with the Gram-positive group may be explained by their similar ability for protection against the biocides, due to the role of the cell envelopes (i.e. glycocalyx and thick cell wall, respectively). Regarding the cluster of K. pneumoniae and C. diversus, their likeness may have resulted from the presence of the same phosphatase-mediated metal accumulation process involved in the detoxification of the bacteria (Macaskie et al. 1994).Fig. 1

Bottom Line: In this study, soil of a metal-mine wasteland was analyzed for the presence of metal-tolerant bacterial isolates, and the tolerance patterns of the isolated strains for a number of heavy metals and antibiotics were compared.From among the successfully tagged isolates, we used the transconjugant Pseudomonas putida G25 (pPROBE-NT) to inoculate white mustard seedlings.Despite a significant decrease in transconjugant abundance in the rhizosphere, the gfp-tagged cells survived on the root surfaces at a level previously reported for root colonisers.

View Article: PubMed Central - PubMed

ABSTRACT
The introduction of rhizobacteria that tolerate heavy metals is a promising approach to support plants involved in phytoextraction and phytostabilisation. In this study, soil of a metal-mine wasteland was analyzed for the presence of metal-tolerant bacterial isolates, and the tolerance patterns of the isolated strains for a number of heavy metals and antibiotics were compared. Several of the multimetal-tolerant strains were tagged with a broad host range reporter plasmid (i.e. pPROBE-NT) bearing a green fluorescent protein marker gene (gfp). Overall, the metal-tolerant isolates were predominately Gram-negative bacteria. Most of the strains showed a tolerance to five metals (Zn, Cu, Ni, Pb and Cd), but with differing tolerance patterns. From among the successfully tagged isolates, we used the transconjugant Pseudomonas putida G25 (pPROBE-NT) to inoculate white mustard seedlings. Despite a significant decrease in transconjugant abundance in the rhizosphere, the gfp-tagged cells survived on the root surfaces at a level previously reported for root colonisers.

No MeSH data available.


Related in: MedlinePlus