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The Lubin underground mine, is one of three mining divisions in the Lubin-Glogow Copper District in Lower Silesia province (Poland). It is the source of polymetallic ore that is rich in copper, silver and several heavy metals. Black shale is also significantly enriched in fossil organic matter in the form of long-chain hydrocarbons, polycyclic aromatic hydrocarbons, organic acids, esters, thiophenes and metalloporphyrins. Biological analyses have revealed that this environment is inhabited by extremophilic bacteria and fungi. Kupfershiefer black shale and samples of water, bottom and mineral sediments from the underground (below 600 m) Lubin mine were taken and 20 bacterial strains were isolated and characterized. All exhibited multi-resistant and hypertolerant phenotypes to heavy metals. We analyzed the plasmidome of these strains in order to evaluate the diversity and role of mobile DNA in adaptation to the harsh conditions of the mine environment. Experimental and bioinformatic analyses of 11 extrachromosomal replicons were performed. Three plasmids, including a broad-host-range replicon containing a Tn3 family transposon, carried genes conferring resistance to arsenic, cadmium, cobalt, mercury and zinc. Functional analysis revealed that the resistance modules exhibit host specificity, i.e., they may increase or decrease tolerance to toxic ions depending on the host strain. The other identified replicons showed diverse features. Among them we identified a catabolic plasmid encoding enzymes involved in the utilization of histidine and vanillate, a putative plasmid-like prophage carrying genes responsible for NAD biosynthesis, and two repABC-type plasmids containing virulence-associated genes. These findings provide an unique molecular insight into the pool of extrachromosomal replicons and highlight their role in the biology and adaptation of extremophilic bacteria inhabiting terrestrial deep subsurface. [ABSTRACT FROM AUTHOR]

Phenotypic and genotypic resistance to benzalkonium chloride (BC), cadmium and arsenic was tested (by susceptibility assays and molecular methods) in 287 Listeria monocytogenes strains isolated from fish and fish products, and food-producing factories in Poland. Overall, 40% of the isolates were resistant to BC, 56% to cadmium and 41% to arsenic (57% displayed resistance to more than one of the tested compounds). Among BC-resistant isolates, the most commonly detected resistance determinant was the qacH gene (83%). Three distinct types of cadA gene determining resistance to cadmium were detected, with the cadA1 variant predominant (88%), while most arsenic-resistant isolates (86%) harbored the arsA gene associated with a Tn 554- like transposon (one strain harbored two copies of arsA in different arsenic resistance cassettes). 53% of all tested isolates contained plasmids (from 4 kb to > 90 kb in size), which were classified into 11 groups (p1–p11) based on their restriction patterns. Interestingly, 12 isolates harbored the small mobilizable pLMST6-like plasmid pLIS3 encoding multidrug efflux pump EmrC. Clustering analysis of PFGE patterns revealed that these isolates represent several diverse bacterial populations, which strongly suggests mobility of the pLMST6-like plasmids among L. monocytogenes strains and their role in dissemination of BC resistance. • Among 287 Listeria monocytogenes isolates, 40% were resistant to benzalkonium chloride, 56% to cadmium and 41% to arsenic. • 83% of isolates resistant to benzalkonium chloride carried the qacH gene. • 88% of cadmium-resistant isolates carried the cadA1 gene. • 86% of isolates resistant to arsenic harbored the Tn 554 associated arsA gene. • 4% of isolates carried a mobilizable pLMST6-like plasmid pLIS3 encoding multidrug efflux pump EmrC. [ABSTRACT FROM AUTHOR]

Background: Halomonas sp. ZM3 was isolated from Zelazny Most post-flotation mineral waste repository (Poland), which is highly contaminated with heavy metals and various organic compounds. Mobile DNA of the strain (i.e. plasmids and transposons) were analyzed in order to identify genetic information enabling adaptation of the bacterium to the harsh environmental conditions., Results: The analysis revealed that ZM3 carries plasmid pZM3H1 (31,370 bp), whose replication system may be considered as an archetype of a novel subgroup of IncU-like replicons. pZM3H1 is a narrow host range, mobilizable plasmid (encodes a relaxase of the MOBV family) containing mercury resistance operon (mer) and czcD genes (mediate resistance to zinc and cobalt), which are part of a large truncated Tn3 family transposon. Further analysis demonstrated that the phenotypes determined by the pZM3H1 resistance cassette are highly dependent on the host strain. In another strand of the study, the trap plasmid pMAT1 was employed to identify functional transposable elements of Halomonas sp. ZM3. Using the sacB positive selection strategy two insertion sequences were identified: ISHsp1 - representing IS5 group of IS5 family and ISHsp2 - a distinct member of the IS630 family., Conclusions: This study provides the first detailed description of mobile DNA in a member of the family Halomonadaceae. The identified IncU plasmid pZM3H1 confers resistance phenotypes enabling adaptation of the host strain to the Zelazny Most environment. The extended comparative analysis has shed light on the distribution of related IncU plasmids among bacteria, which, in many cases, reflects the frequency and direction of horizontal gene transfer events. Our results also identify plasmid-encoded modules, which may form the basis of novel shuttle vectors, specific for this group of halophilic bacteria.