a b s t r a c tAflatoxin B1 (AFB1) and zearalenone (ZON) are hazardous mycotoxins. AFB1 has cytotoxic, mutagenic and carcinogenic effects, whereas ZON can disrupt the endocrine system. Biodegradation by microbes is an effective method to eliminate these hazardous toxins. The aim of this work was to screen AFB1 and ZON biodegrading potential of one hundred and twenty-four Streptomyces strains deposited in the Actinomycetes strain collection of the Department of Environmental Safety and Ecotoxicology. Two different biotests were used for screening purposes: SOS-Chromotest was used to monitor genotoxicity and select microorganisms with the best AFB1 degrading potential. Estrogenic effect of ZON was measured with a yeast based bioluminescent test including human estrogen receptors Bioluminescent Yeast Estrogen System (BLYES). Biodegradation experiments were conducted with 1 mg l À1 AFB1 and 1 mg l À1 ZON concentration. On the base of the results, ten strains were selected for biodegradation experiments and Enzyme-linked Immunosorbent Assay tests (ELISA). The results of these tests Streptomyces cacaoi subsp. asoensis (K234) strain degraded AFB1 over 88 per cent and totally eliminated genotoxicity. Two strains of Streptomyces rimosus (K145, K189) degraded almost total amount of ZON and estrogenicity was not detected besides that.

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To develop effective bioremediation strategies, it is always important to explore autochthonous microbial community diversity using substrate-specific enrichment. The primary objective of this present study was to reveal the diversity of aerobic xylene-degrading bacteria at a legacy BTEX-contaminated site where xylene is the predominant contaminant, as well as to identify potential indigenous strains that could effectively degrade xylenes, in order to better understand the underlying facts about xylene degradation using a multi-omics approach. Henceforward, parallel aerobic microcosms were set up using different xylene isomers as the sole carbon source to investigate evolved bacterial communities using both culture-dependent and independent methods. Research outcome showed that the autochthonous community of this legacy BTEX-contaminated site has the capability to remove all of the xylene isomers from the environment aerobically employing different bacterial groups for different xylene isomers. Interestingly, polyphasic analysis of the enrichments disclose that the community composition of the o-xylene-degrading enrichment community was utterly distinct from that of the m- and p-xylene-degrading enrichments. Although in each of the enrichments Pseudomonas and Acidovorax were the dominant genera, in the case of o-xylene-degrading enrichment Rhodococcus was the main player. Among the isolates, two Hydogenophaga strains, belonging to the same genomic species, were obtained from p-xylene-degrading enrichment, substantially able to degrade aromatic hydrocarbons including xylene isomers aerobically. Comparative whole-genome analysis of the strains revealed different genomic adaptations to aromatic hydrocarbon degradation, providing an explanation on their different xylene isomer-degrading abilities.

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...