# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 6753 | 0 | 1.0000 | Survival of subsurface microorganisms exposed to UV radiation and hydrogen peroxide. Aerobic and microaerophilic subsurface bacteria were screened for resistance to UV light. Contrary to the hypothesis that subsurface bacteria should be sensitive to UV light, the organisms studied exhibited resistance levels as efficient as those of surface bacteria. A total of 31% of the aerobic subsurface isolates were UV resistant, compared with 26% of the surface soil bacteria that were tested. Several aerobic, gram-positive, pigmented, subsurface isolates exhibited greater resistance to UV light than all of the reference bacterial strains tested except Deinococcus radiodurans. None of the microaerophilic, gram-negative, nonpigmented, subsurface isolates were UV resistant; however, these isolates exhibited levels of sensitivity similar to those of the gram-negative reference bacteria Escherichia coli B and Pseudomonas fluorescens. Photoreactivation activity was detected in three subsurface isolates, and strain UV3 exhibited a more efficient mechanism than E. coli B. The peroxide resistance of four subsurface isolates was also examined. The aerobic subsurface bacteria resistant to UV light tolerated higher levels of H2O2 than the microaerophilic organisms. The conservation of DNA repair pathways in subsurface microorganisms may be important in maintaining DNA integrity and in protecting the organisms against chemical insults, such as oxygen radicals, during periods of slow growth. | 1993 | 8285661 |
| 487 | 1 | 0.9997 | Chromosome-encoded inducible copper resistance in Pseudomonas strains. Nine Pseudomonas strains were selected by their high copper tolerance from a population of bacteria isolated from heavy-metal polluted zones. Copper resistance (Cu(r)) was inducible by previous exposure of cultures to subinhibitory amounts of copper sulfate. All nine strains possessed large plasmids, but transformation and curing results suggest that Cu(r) is conferred by chromosomal genes. Plasmid-less Pseudomonas aeruginosa PAO-derived strains showed the same level of Cu(r) as environmental isolates and their resistance to copper was also inducible. Total DNA from the environmental Pseudomonas, as well as from P. aeruginosa PAO strains, showed homology to a Cu(r) P. syringae cop probe at low-stringency conditions but failed to hybridize at high-stringency conditions. | 1995 | 8572680 |
| 6109 | 2 | 0.9997 | Studies on arsenic transforming groundwater bacteria and their role in arsenic release from subsurface sediment. Ten different Gram-negative arsenic (As)-resistant and As-transforming bacteria isolated from As-rich groundwater of West Bengal were characterized to assess their role in As mobilization. 16S rRNA gene analysis confirmed the affiliation of these bacteria to genera Achromobacter, Brevundimonas, Rhizobium, Ochrobactrum, and Pseudoxanthomonas. Along with superior As-resistance and As-transformation abilities, the isolates showed broad metabolic capacity in terms of utilizing a variety of electron donors and acceptors (including As) under aerobic and anaerobic conditions, respectively. Arsenic transformation studies performed under various conditions indicated highly efficient As(3+) oxidation or As(5+) reduction kinetics. Genes encoding As(3+) oxidase (aioA), cytosolic As(5+) reductase (arsC), and As(3+) efflux pump (arsB and acr3) were detected within the test isolates. Sequence analyses suggested that As homeostasis genes (particularly arsC, arsB, and acr3) were acquired by most of the bacteria through horizontal gene transfer. A strong correlation between As resistance phenotype and the presence of As(3+) transporter genes was observed. Microcosm study showed that bacterial strain having cytosolic As(5+) reductase property could play important role in mobilizing As (as As(3+)) from subsurface sediment. | 2014 | 24764001 |
| 3792 | 3 | 0.9997 | Transfer and expression of a multiple antibiotic resistance plasmid in marine bacteria. Conjugal transfer of a multiresistance plasmid from Pseudomonas fluorescens to halophilic and halotolerant bacteria was studied under in vitro and in situ conditions. Mating conducted in broth as well as on plates yielded a plasmid transfer frequency of as high as 10(-3). Among these two, plate mating facilitated conjugal transfer of plasmid, because the cell-to-cell contact is more in plate mating. When P. fluorescens was incubated in seawater, the organism progressively lost its colony forming activity within 15 days. Microscopic examination revealed the presence of very short rods, indicating that the cells have become viable but nonculturable (VNC). Mating conducted in natural seawater without any added nutrients revealed that the conjugal transfer is influenced by the physical state of the donor and the recipients as well as the availability of nutrients. But a plasmid transfer frequency of 10(-7) was obtained even after the donor cells have become VNC suggesting that the nonculturable state and nutrient deprived condition may not limit plasmid transfer. The results suggest that the terrestrial bacteria entering into the seawaters with antibiotic resistance plasmids may be responsible for the prevalence of resistance genes in the marine environment. | 1998 | 9767716 |
| 4573 | 4 | 0.9997 | High pressure processing, acidic and osmotic stress increased resistance to aminoglycosides and tetracyclines and the frequency of gene transfer among strains from commercial starter and protective cultures. This study analyzed the effect of food-related stresses on the expression of antibiotic resistance of starter and protective strains and resistance gene transfer frequency. After exposure to high-pressure processing, acidic and osmotic stress, the expression of genes encoding resistance to aminoglycosides (aac(6')Ie-aph(2″)Ia and aph(3')-IIIa) and/or tetracyclines (tetM) increased. After cold stress, a decrease in the expression level of all tested genes was observed. The results obtained in the gene expression analysis correlated with the results of the phenotype patterns. After acidic and osmotic stresses, a significant increase in the frequency of each gene transfer was observed. To the best of the authors' knowledge, this is the first study focused on changes in antibiotic resistance associated with a stress response among starter and protective strains. The results suggest that the physicochemical factors prevailing during food production and storage may affect the phenotype of antibiotic resistance and the level of expression of antibiotic resistance genes among microorganisms. As a result, they can contribute to the spread of antibiotic resistance. This points to the need to verify strains used in the food industry for their antibiotic resistance to prevent them from becoming a reservoir for antibiotic resistance genes. | 2022 | 35953184 |
| 3710 | 5 | 0.9997 | Tolerance to various toxicants by marine bacteria highly resistant to mercury. Bacteria highly resistant to mercury isolated from seawater and sediment samples were tested for growth in the presence of different heavy metals, pesticides, phenol, formaldehyde, formic acid, and trichloroethane to investigate their potential for growth in the presence of a variety of toxic xenobiotics. We hypothesized that bacteria resistant to high concentrations of mercury would have potential capacities to tolerate or possibly degrade a variety of toxic materials and thus would be important in environmental pollution bioremediation. The mercury-resistant bacteria were found to belong to Pseudomonas, Proteus, Xanthomonas, Alteromonas, Aeromonas, and Enterobacteriaceae. All these environmental bacterial strains tolerant to mercury used in this study were capable of growth at a far higher concentration (50 ppm) of mercury than previously reported. Likewise, their ability to grow in the presence of toxic xenobiotics, either singly or in combination, was superior to that of bacteria incapable of growth in media containing 5 ppm mercury. Plasmid-curing assays done in this study ascertained that resistance to mercury antibiotics, and toxic xenobiotics is mediated by chromosomally borne genes and/or transposable elements rather than by plasmids. | 2003 | 12876655 |
| 6346 | 6 | 0.9996 | Identification of unknown acid-resistant genes of oral microbiotas in patients with dental caries using metagenomics analysis. Acid resistance is critical for the survival of bacteria in the dental caries oral micro-environment. However, there are few acid-resistant genes of microbiomes obtained through traditional molecular biology experimental techniques. This study aims to try macrogenomics technologies to efficiently identify acid-resistant genes in oral microbes of patients with dental caries. Total DNA was extracted from oral microbiota obtained from thirty dental caries patients and subjected to high-throughput sequencing. This data was used to build a metagenomic library, which was compared to the sequences of two Streptococcus mutant known acid-resistant genes, danK and uvrA, using a BLAST search. A total of 19 and 35 unknown gene sequences showed similarities with S. mutans uvrA and dnaK in the metagenomic library, respectively. Two unknown genes, mo-dnaK and mo-uvrA, were selected for primer design and bioinformatic analysis based on their sequences. Bioinformatics analysis predicted them encoding of a human heat-shock protein (HSP) 70 and an ATP-dependent DNA repair enzyme, respectively, closely related with the acid resistance mechanism. After cloning, these genes were transferred into competent Escherichia coli for acid resistance experiments. E. coli transformed with both genes demonstrated acid resistance, while the survival rate of E. coli transformed with mo-uvrA was significantly higher in an acidic environment (pH = 3). Through this experiment we found that identify unknown acid-resistant genes in oral microbes of patients with caries by establishing a metagenomic library is very efficient. Our results provide an insight into the mechanisms and pathogenesis of dental caries for their treatment without affecting oral probiotics. | 2021 | 33675438 |
| 8456 | 7 | 0.9996 | Identification of genes required by Bacillus thuringiensis for survival in soil by transposon-directed insertion site sequencing. Transposon-directed insertion site sequencing was used to identify genes required by Bacillus thuringiensis to survive in non-axenic plant/soil microcosms. A total of 516 genetic loci fulfilled the criteria as conferring survival characteristics. Of these, 127 (24.6 %) were associated with uptake and transport systems; 227 loci (44.0 %) coded for enzymatic properties; 49 (9.5 %) were gene regulation or sensory loci; 40 (7.8 %) were structural proteins found in the cell envelope or had enzymatic activities related to it and 24 (4.7 %) were involved in the production of antibiotics or resistance to them. Eighty-three (16.1 %) encoded hypothetical proteins or those of unknown function. The ability to form spores was a key survival characteristic in the microcosms: bacteria, inoculated in either spore or vegetative form, were able to multiply and colonise the soil, whereas a sporulation-deficient mutant was not. The presence of grass seedlings was critical to colonisation. Bacteria labelled with green fluorescent protein were observed to adhere to plant roots. The sporulation-specific promoter of spo0A, the key regulator of sporulation, was strongly activated in the rhizosphere. In contrast, the vegetative-specific promoters of spo0A and PlcR, a pleiotropic regulator of genes with diverse activities, were only very weakly activated. | 2014 | 24310935 |
| 8218 | 8 | 0.9996 | Mechanism of plasmic-mediated resistance to cadmium in Staphylococcus aureus. The mechanism of plasmid-mediated resistance to cadmium in Staphylococcus aureus was investigated. Protein synthesis in cell-free extracts from resistant or susceptible bacteria was equally susceptible to inhibition by Cd(2+), but spheroplasts from resistant bacteria retained their resistance. Resistant bacteria did not have a decreased affinity for cations in general, nor was active metabolism required for exclusion of Cd(2+). The kinetics of Cd(2+) uptake into susceptible and resistant bacteria suggested that the conformation of membrane proteins in resistant bacteria may be important in the exclusion of Cd(2+). | 1975 | 1137361 |
| 4496 | 9 | 0.9996 | Phenotypic and genetic barriers to establishment of horizontally transferred genes encoding ribosomal protection proteins. BACKGROUND: Ribosomal protection proteins (RPPs) interact with bacterial ribosomes to prevent inhibition of protein synthesis by tetracycline. RPP genes have evolved from a common ancestor into at least 12 distinct classes and spread by horizontal genetic transfer into a wide range of bacteria. Many bacterial genera host RPP genes from multiple classes but tet(M) is the predominant RPP gene found in Escherichia coli. OBJECTIVES: We asked whether phenotypic barriers (low-level resistance, high fitness cost) might constrain the fixation of other RPP genes in E. coli. METHODS: We expressed a diverse set of six different RPP genes in E. coli, including tet(M), and quantified tetracycline susceptibility and growth phenotypes as a function of expression level, and evolvability to overcome identified phenotypic barriers. RESULTS: The genes tet(M) and tet(Q) conferred high-level tetracycline resistance without reducing fitness; tet(O) and tet(W) conferred high-level resistance but significantly reduced growth fitness; tetB(P) conferred low-level resistance and while mutants conferring high-level resistance were selectable these had reduced growth fitness; otr(A) did not confer resistance and resistant mutants could not be selected. Evolution experiments suggested that codon usage patterns in tet(O) and tet(W), and transcriptional silencing associated with nucleotide composition in tetB(P), accounted for the observed phenotypic barriers. CONCLUSIONS: With the exception of tet(Q), the data reveal significant phenotypic and genetic barriers to the fixation of additional RPP genes in E. coli. | 2021 | 33655294 |
| 3789 | 10 | 0.9996 | The fate of antibiotic resistance marker genes in transgenic plant feed material fed to chickens. We have examined the fate of an antibiotic resistance marker, incorporated into transgenic maize when fed to chicks. Plant-derived markers were found in the crops of five birds fed transgenic maize and in the stomach contents of two birds. The plant-derived marker gene was not found in the intestines. The survival of the antibiotic resistance marker gene mirrored that of plant DNA targets, demonstrating that it survives no better than other DNA and indicating that it is very unlikely that bacteria in the gut of chickens will be transformed to ampicillin resistance when the birds are fed transgenic maize. | 2002 | 11751781 |
| 6754 | 11 | 0.9996 | Real-time PCR based analysis of metal resistance genes in metal resistant Pseudomonas aeruginosa strain J007. A uranium (U)-resistant and -accumulating Pseudomonas aeruginosa strain was characterized to assess the response of toxic metals toward its growth and expression of metal resistance determinants. The bacterium showed MIC (minimum inhibitory concentration) values of 6, 3, and 2 mM for Zn, Cu, and Cd, respectively; with resistance phenotype conferred by periplasmic Cu sequestering copA and RND type heavy metal efflux czcA genes. Real-time PCR-based expression analysis revealed significant upregulation of both these genes upon exposure to low concentrations of metals for short duration, whereas the global stress response gene sodA encoding superoxide dismutase enzyme was upregulated only at higher metal concentrations or longer exposure time. It could also be inferred that copA and czcA are involved in providing resistance only at low metal concentrations, whereas involvement of "global stress response" phenomenon (expression of sodA) at higher metal concentration or increased exposure was evident. This study provides significant understanding of the adaptive response of bacteria surviving in metal and radionuclide contaminated environments along with the development of real-time PCR-based quantification method of using metal resistance genes as biomarker for monitoring relevant bacteria in such habitats. | 2016 | 26662317 |
| 4571 | 12 | 0.9996 | Growth of soil bacteria, on penicillin and neomycin, not previously exposed to these antibiotics. There is growing evidence that bacteria, in the natural environment (e.g. the soil), can exhibit naturally occurring resistance/degradation against synthetic antibiotics. Our aim was to assess whether soils, not previously exposed to synthetic antibiotics, contained bacterial strains that were not only antibiotic resistant, but could actually utilize the antibiotics for energy and nutrients. We isolated 19 bacteria from four diverse soils that had the capability of growing on penicillin and neomycin as sole carbon sources up to concentrations of 1000 mg L(-1). The 19 bacterial isolates represent a diverse set of species in the phyla Proteobacteria (84%) and Bacteroidetes (16%). Nine antibiotic resistant genes were detected in the four soils but some of these genes (i.e. tetM, ermB, and sulI) were not detected in the soil isolates indicating the presence of unculturable antibiotic resistant bacteria. Most isolates that could subsist on penicillin or neomycin as sole carbon sources were also resistant to the presence of these two antibiotics and six other antibiotics at concentrations of either 20 or 1000 mg L(-1). The potentially large and diverse pool of antibiotic resistant and degradation genes implies ecological and health impacts yet to be explored and fully understood. | 2014 | 24956077 |
| 6104 | 13 | 0.9996 | The Pseudomonas community in metal-contaminated sediments as revealed by quantitative PCR: a link with metal bioavailability. Pseudomonas bacteria are ubiquitous Gram-negative and aerobic microorganisms that are known to harbor metal resistance mechanisms such as efflux pumps and intracellular redox enzymes. Specific Pseudomonas bacteria have been quantified in some metal-contaminated environments, but the entire Pseudomonas population has been poorly investigated under these conditions, and the link with metal bioavailability was not previously examined. In the present study, quantitative PCR and cell cultivation were used to monitor and characterize the Pseudomonas population at 4 different sediment sites contaminated with various levels of metals. At the same time, total metals and metal bioavailability (as estimated using an HCl 1 m extraction) were measured. It was found that the total level of Pseudomonas, as determined by qPCR using two different genes (oprI and the 16S rRNA gene), was positively and significantly correlated with total and HCl-extractable Cu, Co, Ni, Pb and Zn, with high correlation coefficients (>0.8). Metal-contaminated sediments featured isolates of the Pseudomonas putida, Pseudomonas fluorescens, Pseudomonas lutea and Pseudomonas aeruginosa groups, with other bacterial genera such as Mycobacterium, Klebsiella and Methylobacterium. It is concluded that Pseudomonas bacteria do proliferate in metal-contaminated sediments, but are still part of a complex community. | 2014 | 25102022 |
| 6321 | 14 | 0.9996 | An active β-lactamase is a part of an orchestrated cell wall stress resistance network of Bacillus subtilis and related rhizosphere species. A hallmark of the Gram-positive bacteria, such as the soil-dwelling bacterium Bacillus subtilis, is their cell wall. Here, we report that d-leucine and flavomycin, biofilm inhibitors targeting the cell wall, activate the β-lactamase PenP. This β-lactamase contributes to ampicillin resistance in B. subtilis under all conditions tested. In contrast, both Spo0A, a master regulator of nutritional stress, and the general cell wall stress response, differentially contribute to β-lactam resistance under different conditions. To test whether β-lactam resistance and β-lactamase genes are widespread in other Bacilli, we isolated Bacillus species from undisturbed soils, and found that their genomes can encode up to five β-lactamases with differentiated activity spectra. Surprisingly, the activity of environmental β-lactamases and PenP, as well as the general stress response, resulted in a similarly reduced lag phase of the culture in the presence of β-lactam antibiotics, with little or no impact on the logarithmic growth rate. The length of the lag phase may determine the outcome of the competition between β-lactams and β-lactamases producers. Overall, our work suggests that antibiotic resistance genes in B. subtilis and related species are ancient and widespread, and could be selected by interspecies competition in undisturbed soils. | 2019 | 30637927 |
| 268 | 15 | 0.9996 | Amplification of bacitracin transporter genes in the bacitracin producing Bacillus licheniformis. We have amplified the previously cloned and sequenced genes of the bacitracin exporter (bcr), a member of the ATP-binding transport protein family, within the chromosome of the bacitracin producing Bacillus licheniformis. Amplification of the transporter genes was followed by greatly increased bacitracin resistance. Antibiotic production was enhanced at a low level of bcr genes amplification. An enlarged increase in the copy number of the bcr genes negatively affects the overall growth of bacteria. | 1997 | 9418256 |
| 9270 | 16 | 0.9996 | Activation of class 1 integron integrase is promoted in the intestinal environment. Class 1 integrons are widespread genetic elements playing a major role in the dissemination of antibiotic resistance. They allow bacteria to capture, express and exchange antibiotic resistance genes embedded within gene cassettes. Acquisition of gene cassettes is catalysed by the class 1 integron integrase, a site-specific recombinase playing a key role in the integron system. In in vitro planktonic culture, expression of intI1 is controlled by the SOS response, a regulatory network which mediates the repair of DNA damage caused by a wide range of bacterial stress, including antibiotics. However, in vitro experimental conditions are far from the real lifestyle of bacteria in natural environments such as the intestinal tract which is known to be a reservoir of integrons. In this study, we developed an in vivo model of intestinal colonization in gnotobiotic mice and used a recombination assay and quantitative real-time PCR, to investigate the induction of the SOS response and expression and activity of the class 1 integron integrase, IntI1. We found that the basal activity of IntI1 was higher in vivo than in vitro. In addition, we demonstrated that administration of a subinhibitory concentration of ciprofloxacin rapidly induced both the SOS response and intI1 expression that was correlated with an increase of the activity of IntI1. Our findings show that the gut is an environment in which the class 1 integron integrase is induced and active, and they highlight the potential role of integrons in the acquisition and/or expression of resistance genes in the gut, particularly during antibiotic therapy. | 2022 | 35482826 |
| 6755 | 17 | 0.9996 | Impact of lead (Pb(2+)) on the growth and biological activity of Serratia marcescens selected for wastewater treatment and identification of its zntR gene-a metal efflux regulator. Microorganisms isolated from contaminated areas play an important role in bioremediation processes. They promote heavy metal removal from the environment by adsorbing ions onto the cell wall surface, accumulating them inside the cells, or reducing, complexing, or precipitating these substances in the environment. Microorganism-based bioremediation processes can be highly efficient, low-cost and have low environmental impact. Thus, the present study aimed to select Pb(2+)-resistant bacteria and evaluate the growth rate, biological activity, and the presence of genes associated with metal resistance. Serratia marcescens CCMA 1010, that was previously isolated from coffee processing wastewater, was selected since was able to growth in Pb(2+) concentrations of up to 4.0 mM. The growth rate and generation time did not differ from those of the control (without Pb(2+)), although biological activity decreased in the first hour of exposure to these ions and stabilized after this period. The presence of the zntR, zntA and pbrA genes was analysed, and only zntR was detected. The zntR gene encodes a protein responsible for regulating the production of ZntA, a transmembrane protein that facilitates Pb(2+) extrusion out of the cell. S. marcescens CCMA 1010 demonstrated a potential for use as bioindicator that has potential to be used in bioremediation processes due to its resistance to high concentrations of Pb(2+), ability to grow until 24 h of exposure, and possession of a gene that indicates the existence of mechanisms associated with resistance to lead (Pb(2+)). | 2023 | 36752862 |
| 9007 | 18 | 0.9996 | Genes involved in copper resistance influence survival of Pseudomonas aeruginosa on copper surfaces. AIMS: To evaluate the killing of Pseudomonas aeruginosa PAO1 on copper cast alloys and the influence of genes on survival on copper containing medium and surfaces. METHODS AND RESULTS: Different strains of P. aeruginosa were inoculated on copper containing medium or different copper cast alloys and the survival rate determined. The survival rates were compared with rates on copper-free medium and stainless steel as control. In addition, the effect of temperature on survival was examined. CONCLUSIONS: Copper cast alloys had been previously shown to be bactericidal to various bacteria, but the mechanism of copper-mediated killing is still not known. In this report, we demonstrate that P. aeruginosa PAO1 is rapidly killed on different copper cast alloys and that genes involved in conferring copper resistance in copper-containing medium also influenced survival on copper cast alloys. We also show that the rate of killing is influenced by temperature. SIGNIFICANCE AND IMPACT OF THE STUDY: To use copper surfaces more widely as bactericidal agents in various settings, it is important to understand how genes influence survival on these surfaces. Here we show that genes shown to be involved in copper resistance in P. aeruginosa PAO1 can have an impact on the length of survival time on copper cast alloys under certain conditions. This is an important first step for evaluation of future use of copper surfaces as bactericidal agents. | 2009 | 19239551 |
| 6743 | 19 | 0.9996 | Impact of acute and chronic exposure to sulfamethoxazole on the kinetics and microbial structure of an activated sludge community. The aim of this study was to reveal the microbial and kinetic impacts of acute and chronic exposure to one of the frequently administered antibiotics, i.e., sulfamethoxazole, on an activated sludge biomass. Respirometric analysis and model evaluation of the oxygen utilization rate profiles were the backbone of this study. The results showed that continuous exposure to sulfamethoxazole resulted in the inhibition of substrate storage and an increase in the endogenous decay rates by twofold, which was supported by analysis of the resistance genes. A mild inhibition on the growth and hydrolysis kinetics was also observed. Moreover, sulfamethoxazole had a binding impact with available organic carbon, resulting in a slightly less oxygen consumption. DNA sequencing and antibiotic resistance gene analyses showed that continuous exposure to sulfamethoxazole caused a change in the community structure at the species level. Resistant bacteria including Arthrobacter sp. and members of the Chitinophagaceae and Intrasporangiaceae families were found to have dominated the bacterial community. The impact of intermittent exposure was also investigated, and the results indicated a drop in the severity of the impact after 20 days of intermittence. | 2024 | 39816257 |