No abstract

Soil pollution from heavy metals, especially mercury, is an environmental problem for human health. Biological approaches offer interesting tools, which necessarily involve the selection of organisms capable of transforming the environment via bioremediation. To evaluate the potential use of microorganisms in phytorhizoremediation, bacterial strains were isolated from rhizospheric and bulk soil under conditions of chronic natural mercury, which were identified and characterized by studying the following: (i) their plant growth promoting rhizobacteria (PGPR) activities; and (ii) their maximum bactericide concentration of mercury. Information regarding auxin production, phosphate solubilization, siderophore synthesis and 1-aminocyclopropane-1-carboxylic acid deaminase (ACCd) capacity of the isolates was compiled in order to select the strains that fit potential biotechnological use. To achieve this objective, the present work proposes the Bio-Mercury Remediation Suitability Index (BMR-SI), which reflects the integral behavior of the strains for heavy metal polluted soil bioremediation. Only those strains that rigorously fulfilled all of the established criteria were selected for further assays.

A total of 595 faecal samples from raptorial birds, either captive or free-living, residing in GREFA Wildlife Hospital were bacteriologically examined using various selective media and an Automated Diagnostic Assay System for Salmonella detection. Serotype and phage type of the strains identified as Salmonella was determined. In the captive group, of the 285 samples examined, 21 (7.36%) were positive for Salmonella. Serotyping revealed that most of the individuals were infected by Salmonella serotype Havana. This result suggested that there could be a source of contamination in the Hospital although it could not be established. In the wild free-living group, over 310 samples examined (4.19%) were positive for Salmonella. The Salmonella isolates showed a major variety of serotypes: Enteritidis, Adelaide, Brandenburg, Newport, Typhimurium, Hadar, Saintpaul and Virchow. Most of them are similar to those commonly described in isolates from human and domestic animals. These results indicate that wild birds could be involved in the dissemination of Salmonella in humans or domestic animals or vice versa.

Gram-negative bacteria were isolated from knots induced by Pseudomonas savastanoi in olive trees (Olea europaea L.). A total of nine endophytic bacterial strains were isolated, each from inside a different tree knot. Biochemical characterization indicated that all the strains belong to the family Enterobacteriaceae. Phylogenetic analyses of the 16S rRNA genes of these novel isolates revealed that they formed a homogeneous cluster within Erwinia species. DNA signatures of these isolates were identical to those described for the genus Erwinia. The strains formed a homogeneous group as shown by DNA-DNA hybridization analysis and numerical analysis of phenotypic data, clearly differentiated from all species of Erwinia with validly published names. The data provide strong evidence of the differentiation of these strains from the most closely related species. Therefore, these isolates represent a novel species, for which the name Erwinia toletana sp. nov. is proposed. The isolates are available at CFBP, CECT and ATCC. The G+C content is 52±0?5 mol%. The type strain is CFBP 6631 T (=A37 T =ATCC 700880 T =CECT 5263 T ). Ewing & Fife (1971, 1972 concluded that strains isolated from clinical sources and strains belonging to the Herbicola group of Dye (1969) are the same species and referred to them as the 'Enterobacter agglomerans-Erwinia herbicola' complex. Lelliott & Dickey (1984) defined Erwinia as associated with plants as pathogens, saprophytes or constituents of the epiphytic flora. They considered Erwinia herbicola as yellow and non-pigmented Erwinia-like organisms that exist either on plant surfaces or as secondary organisms in lesions caused by many plant pathogens, as described by Billing & Baker (1963). Gavini et al. (1989) described the new genus Pantoea and the species Pantoea agglomerans, which includes the type strains of Enterobacter agglomerans, Erwinia herbicola and Erwinia milletiae. Later, Erwinia ananatis (synonym Erwinia uredovora) and Erwinia stewartii were transferred to the genus Pantoea (Mergaert et al., 1993). Based on 16S rRNA gene phylogenetic analyses, plant-associated bacteria were reclassified into four genera: Erwinia, Pectobacterium, Brenneria and Pantoea (Hauben et al., 1998). Mergaert et al. (1999) reclassified nonpigmented Erwinia herbicola epiphytic strains isolated from trees as Erwinia billingiae, which clades within the first cluster of Hauben et al. (1998).Samples from diseased olive trees were collected from the Navahermosa and Chozas areas in the Toledo region of central Spain. Strains from knots were isolated according to the method of García de los Ríos (1999) and were grown on King's medium B (KB) and nutrient agar for 48 h at 25 uC. Two colony types were easily distinguishable on both agar media. Pure cultures were established by single colony isolation onto fresh KB agar. The first type was identified as Pseudomonas savastanoi. The second type, which corresponded to large (3-5 mm), mucilaginous, pigmented and non-pigmented colonies, was identified as a member of 3Present a...

Soil contamination by mercury, which is one of the most toxic heavy metals due to its bioaccumulative capacity, poses a risk to the environment as well as health. The Almadén mining district in Ciudad Real, Spain is one of the most heavily-polluted sites in the world, making the soils unusable. Bioremediation, and more specifically phyto-rhizoremediation, based on the synergistic interaction established between plant and Plant Growth Promoting Rhizobacteria (PGPR), improves the plant's ability to grow, mobilize, accumulate, and extract contaminants from the soil. The objective of this study is to evaluate the plant growth-promoting ability of four PGPR strains (and mixtures), isolated from the bulk soil and rhizosphere of naturally grown plants in the Almadén mining district, when they are inoculated in emerged seeds of Lupinus albus, var. Dorado in the presence of high concentrations of mercury. After 20 days of incubation and subsequent harvesting of the seedlings, biometric measurements were carried out at the root and aerial levels. The results obtained show that the seeds treatment with PGPR strains improves plants biometry in the presence of mercury. Specifically, strain B2 (Pseudomonas baetica) and B1 (Pseudomonas moraviensis) were those that contributed the most to plant growth, both individually and as part of mixtures (CS5 and CS3). Thus, these are postulated to be good candidates for further in situ phyto-rhizoremediation tests of mercury-contaminated soils.