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Pseudomonas aeruginosa is a major public health concern all around the world. In the frame of this work, a set of diverse environmental P. aeruginosa isolates with various antibiotic resistance profiles were examined in a Galleria mellonella virulence model. Motility, serotypes, virulence factors and biofilm-forming ability were also examined. Molecular types were determined by pulsed-field gel electrophoresis (PFGE). Based on our results, the majority of environmental isolates were virulent in the G. mellonella test and twitching showed a positive correlation with mortality. Resistance against several antibiotic agents such as Imipenem correlated with a lower virulence in the applied G. mellonella model. PFGE revealed that five examined environmental isolates were closely related to clinically detected pulsed-field types. Our study demonstrated that industrial wastewater effluents, composts, and hydrocarboncontaminated sites should be considered as hot spots of high-risk clones of P. aeruginosa.

The main aim of this paper was the comprehensive estimation of the occurrence rate and the antibiotic-resistance conditions of opportunistic pathogen Pseudomonas aeruginosa in hydrocarbon-contaminated environments. From 2002 to 2007, 26 hydrocarbon-contaminated sites of Hungary were screened for the detection of environmental isolates. Altogether, 156 samples were collected and examined for the determination of appearance, representative cell counts, and antibiotic-resistance features of P. aeruginosa. The detected levels of minimal inhibitory concentrations of ten different drugs against 36 environmental strains were compared to the results of a widely used reference strain ATCC 27853 and four other clinical isolates of P. aeruginosa. Based on our long-term experiment, it can be established that species P. aeruginosa was detectable in case of 61.5% of the investigated hydrocarbon-contaminated sites and 35.2% of the examined samples that shows its widespread occurrence in polluted soil-groundwater systems. In the course of the antibiotic-resistance assay, our results determined that 11 of the examined 36 environmental strains had multiple drug-resistance against several clinically effective antimicrobial classes: cephalosporins, wide spectrum penicillins, carbapenems, fluoroquinolones, and aminoglycosides. The fact that these multiresistant strains were isolated from 8 different hydrocarbon-contaminated sites, mainly from outskirts, confirms that multiple drug-resistance of P. aeruginosa is widespread not only in clinical, but also in natural surroundings as well.

A novel hydrocarbon-degrading, Gram-negative, obligately aerobic, non-motile, non-sporulating, rod-shaped bacterium, designated strain TBF2/20.2 T , was isolated from a biofilter clean-up facility set up on a hydrocarbon-contaminated site in Hungary. It was characterized by using a polyphasic approach to determine its taxonomic position. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate is affiliated with the genus Olivibacter in the family Sphingobacteriaceae. It was found to be related most closely to Olivibacter ginsengisoli Gsoil 060 T (93.3 % 16S rRNA gene sequence similarity). Strain TBF2/20.2 T grew at pH 6-9 (optimally at pH 6.5-7.0) and at 15-42 6C (optimally at 30-37 6C). The major fatty acids were iso-C 15 : 0 (39.4 %), summed feature 3 (iso-C 15 : 0 2-OH and/or C 16 : 1 v7c; 26.0 %), iso-C 17 : 0 3-OH (14.5 %) and C 16 : 0 (4.5 %). The major menaquinone was MK-7 and the predominant polar lipid was phosphatidylethanolamine. The DNA G+C content of strain TBF2/20.2 T was 41.2 mol%. Physiological and chemotaxonomic data further confirmed the distinctiveness of strain TBF2/20.2 T from recognized members of the genus Olivibacter. Thus, strain TBF2/20.2 T is considered to represent a novel species of the genus Olivibacter, for which the name Olivibacter oleidegradans sp. nov. is proposed. The type strain is TBF2/20.2 T (5NCAIM B 02393 T 5CCM 7765 T ).The genus Olivibacter, family Sphingobacteriaceae (Euzéby, 1997), was proposed by Ntougias et al. (2007) and, at the time of writing, comprised four recognized species: Olivibacter sitiensis, isolated from alkaline olive-oil mill wastes (Ntougias et al., 2007), and Olivibacter ginsengisoli, Olivibacter terrae and Olivibacter soli (Wang et al., 2008), isolated from soil of a ginseng field and compost in South Korea. The present study describes the taxonomic characterization of a novel Olivibacter-like bacterial strain, designated TBF2/20.2 T .Strain TBF2/20.2 T was isolated from a clean-up facility at a volatile hydrocarbon-contaminated site in Hungary. A biofilter was used for bioremediation of contaminated groundwater by using ex situ, on-site treatment. A sample was taken from the biofilter and 10 g of the sample was stirred thoroughly for 20 min in 90 ml physiological saline (0.9 %, w/v, NaCl) solution and glass beads. Serial dilutions were made and plated on TGY5 agar plates [per litre distilled water: 5 g tryptone, 2.5 g yeast extract, 5 g glucose (all from BioLab Inc.) and 15 g agar agar (Merck)] and incubated at 30 u C for 72 h. Colonies were selected randomly and subsequently purified twice on TGY5 agar medium at 30 u C.Hydrocarbon degradation was tested on prediluted and sterilized diesel oil solution prepared by a Hungarian accredited analytical laboratory (Wessling Hungary Ltd). To confirm oil degradation, 450 ml of this solution was inoculated with strain TBF2/20.2 T growing in 50 ml TGY5 broth (final volume 500 ml) and incubated for 5 days in a rotary shaker (120 r.p.m.) at 25 u C. Uninoculated solution with the addi...

The current theses that distinguish isolates originating from different sources are questionable; environmental P. aeruginosa can be a potential risk to public health and cannot be excluded as an external (non-nosocomial) source of infections, especially in patients with CF. Further studies such as pulsed-field gel electrophoresis (PFGE) and the determination of other clinically important virulence factors are needed to confirm these findings.