Role of Biosynthetic Gene Cluster BGC3 in the Cariogenic Virulence of Streptococcus mutans. - Related Documents




#
Rank
Similarity
Title + Abs.
Year
PMID
012345
873701.0000Role of Biosynthetic Gene Cluster BGC3 in the Cariogenic Virulence of Streptococcus mutans. OBJECTIVE: To investigate the role of the biosynthetic gene cluster BGC3 of Streptococcus mutans (S. mutans) in the process of dental caries. METHODS: BGC3 and ∆BGC3 S. mutans strains were constructed and their growth curves were evaluated. Acid production capacity was assessed by evaluating pH reduction levels over identical culture periods. The survival of bacteria in phosphate citrate buffer solution (pH 3.0) was quantified. The expression levels of virulence genes (atpF, gtfC, gtfD, spaP, vicR and ftf) were analysed using the qPCR. Co-culture experiments were conducted to evaluate bacterial adaptability. Bacterial viability was determined by microscopical examination of live/dead staining. RESULTS: Deletion of BGC3 did not significantly impact S. mutans growth or acid production in biofilms. The ∆BGC3 strain exhibited enhanced acid resistance and higher expression levels of virulence genes compared to the wild type. In addition, ∆BGC3 exhibited superior bacterial viability in the co-culture system. CONCLUSION: BGC3 affected the acid resistance and expression of caries-related genes in S. mutans. The BGC3 knockout strain exhibited a more robust survival capability than the wild-type strain.202540162656
623010.9985dpr and sod in Streptococcus mutans are involved in coexistence with S. sanguinis, and PerR is associated with resistance to H2O2. Large numbers of bacteria coexist in the oral cavity. Streptococcus sanguinis, one of the major bacteria in dental plaque, produces hydrogen peroxide (H(2)O(2)), which interferes with the growth of other bacteria. Streptococcus mutans, a cariogenic bacterium, can coexist with S. sanguinis in dental plaque, but to do so, it needs a means of detoxifying the H(2)O(2) produced by S. sanguinis. In this study, we investigated the association of three oxidative stress factors, Dpr, superoxide dismutase (SOD), and AhpCF, with the resistance of S. sanguinis to H(2)O(2). The knockout of dpr and sod significantly increased susceptibility to H(2)O(2), while the knockout of ahpCF had no apparent effect on susceptibility. In particular, dpr inactivation resulted in hypersensitivity to H(2)O(2). Next, we sought to identify the factor(s) involved in the regulation of these oxidative stress genes and found that PerR negatively regulated dpr expression. The knockout of perR caused increased dpr expression levels, resulting in low-level susceptibility to H(2)O(2) compared with the wild type. Furthermore, we evaluated the roles of perR, dpr, and sod when S. mutans was cocultured with S. sanguinis. Culturing of the dpr or sod mutant with S. sanguinis showed a significant decrease in the S. mutans population ratio compared with the wild type, while the perR mutant increased the ratio. Our results suggest that dpr and sod in S. mutans are involved in coexistence with S. sanguinis, and PerR is associated with resistance to H(2)O(2) in regulating the expression of Dpr.201323263955
622820.9984Comparative transcription analysis and toxin production of two fluoroquinolone-resistant mutants of Clostridium perfringens. BACKGROUND: Fluoroquinolone use has been listed as a risk factor for the emergence of virulent clinical strains of some bacteria. The aim of our study was to evaluate the effect of fluoroquinolone (gatifloxacin) resistance selection on differential gene expression, including the toxin genes involved in virulence, in two fluoroquinolone-resistant strains of Clostridium perfringens by comparison with their wild-type isogenic strains. RESULTS: DNA microarray analyses were used to compare the gene transcription of two wild types, NCTR and ATCC 13124, with their gatifloxacin-resistant mutants, NCTRR and 13124R. Transcription of a variety of genes involved in bacterial metabolism was either higher or lower in the mutants than in the wild types. Some genes, including genes for toxins and regulatory genes, were upregulated in NCTRR and downregulated in 13124R. Transcription analysis by quantitative real-time PCR (qRT-PCR) confirmed the altered expression of many of the genes that were affected differently in the fluoroquinolone-resistant mutants and wild types. The levels of gene expression and enzyme production for the toxins phospholipase C, perfringolysin O, collagenase and clostripain had decreased in 13124R and increased in NCTRR in comparison with the wild types. After centrifugation, the cytotoxicity of the supernatants of NCTRR and 13224R cultures for mouse peritoneal macrophages confirmed the increased cytotoxicity of NCTRR and the decreased cytotoxicity of 13124R in comparison with the respective wild types. Fluoroquinolone resistance selection also affected cell shape and colony morphology in both strains. CONCLUSION: Our results indicate that gatifloxacin resistance selection was associated with altered gene expression in two C. perfringens strains and that the effect was strain-specific. This study clearly demonstrates that bacterial exposure to fluoroquinolones may affect virulence (toxin production) in addition to drug resistance.201323452396
622930.9984Response of Bacillus cereus ATCC 14579 to challenges with sublethal concentrations of enterocin AS-48. BACKGROUND: Enterocin AS-48 is produced by Enterococcus faecalis S48 to compete with other bacteria in their environment. Due to its activity against various Gram positive and some Gram negative bacteria it has clear potential for use as a food preservative. Here, we studied the effect of enterocin AS-48 challenges on vegetative cells of Bacillus cereus ATCC 14579 by use of transcriptome analysis. RESULTS: Of the 5200 genes analysed, expression of 24 genes was found to change significantly after a 30 min treatment with a subinhibitory bacteriocin concentration of 0.5 microg/ml. Most of up-regulated genes encode membrane-associated or secreted proteins with putative transmembrane segments or signal sequences, respectively. One operon involved in arginine metabolism was significantly downregulated. The BC4206-BC4207 operon was found to be the most upregulated target in our experiments. BC4206 codes for a PadR type transcriptional regulator, while BC4207 codes for a hypothetical membrane protein. The operon structure and genes are conserved in B. cereus and B. thuringiensis species, but are not present in B. anthracis and B. subtilis. Using real-time qPCR, we show that these genes are upregulated when we treated the cells with AS-48, but not upon nisin treatment. Upon overexpression of BC4207 in B. cereus, we observed an increased resistance against AS-48. Expression of BC4207 in B. subtilis 168, which lacks this operon also showed increased resistance against AS-48. CONCLUSION: BC4207 membrane protein is involved in the resistance mechanism of B. cereus cells against AS-48.200919863785
617240.9984Resistance and susceptibility of mice to bacterial infection. IV. Genetic and cellular basis of resistance to chronic infection with Brucella abortus. The number of Brucella abortus strain 19 organisms in the spleens of CBA/H mice peaked two weeks after intravenous injection of 5 X 10(6) organisms. With the onset of specific cell-mediated immunity, 90% of the bacteria were killed, but approximately 10(6) bacteria persisted up to seven weeks after infection. In contrast, in BALB/c, C57BL/10, and B10Br mice, bacterial numbers peaked at two weeks but decreased steadily with the onset of bactericidal activity. In all strains, clearance of bacteria from the liver was relatively efficient. The course of infection in (CBA/H X BALB/c) F1 mice was similar to that in CBA/H mice, indicating that the mechanism(s) leading to slower recovery from infection was dominant. The H-2 haplotype of the mice did not influence the rate of recovery from infection. The use of backcross mice showed that multiple genes were involved. In bone marrow-chimeric mice, resistance was determined by the genome of the bone marrow donor, not that of the host.19826809847
15850.9983Homology- and cross-resistance of Lactobacillus plantarum to acid and osmotic stress and the influence of induction conditions on its proliferation by RNA-Seq. In this study, homology- and cross-resistance of Lactobacillus plantarum L1 and Lactobacillus plantarum L2 to acid and osmotic stress were investigated. Meanwhile, its proliferation mechanism was demonstrated by transcriptomic analysis using RNA sequencing. We found that the homologous-resistance and cross-resistance of L. plantarum L1 and L. plantarum L2 increased after acid and osmotic induction treatment by lactic acid and sodium lactate solution in advance, and the survival rate of live bacteria was improved. In addition, the count of viable bacteria of L. plantarum L2 significantly increased cultivated at a pH 5.0 with a 15% sodium lactate sublethal treatment, compared with the control group. Further study revealed that genes related to membrane transport, amino acid metabolism, nucleotide metabolism, and cell growth were significantly upregulated. These findings will contribute to promote high-density cell culture of starter cultures production in the fermented food industry.202133945164
878360.9983Characterization and potential of plant growth promoting rhizobacteria isolated from native Andean crops. Bacteria isolated from soil and rhizosphere samples collected in Peru from Andean crops were tested in vitro and in vivo to determine their potential as plant growth promoters and their ability to induce systemic resistance to Alternaria alternata in tomato plants. The isolates were identified by sequencing their 16S ribosomal RNA gene. Test for phosphate solubilization, and indolacetic acid were also carried out, together with in vitro antagonism assays in dual cultures towards the plant pathogens Fusarium solani, A. alternata and Curvularia lunata. The three most promising isolates (Pa15, Ps155, Ps168) belonged to the genus Pseudomonas. Further assays were carried out with tomato plants to assess their plant protection effect towards A. alternata and as growth promoters. Inoculation of tomato seeds with all isolates significantly enhanced seed germination, plantlets emergence and plant development. Bacterial inoculation also reduce damage level caused by A. alternata. The expression levels of three tomato genes involved in the jasmonate (AOS), ethylene responsive (ERF-2) and pathogenesis related (PR-P2) pathways were determined in plants challenged with A. alternata, alone or with each bacterial isolate, respectively. Results showed that at 24 h after infection, in absence of the pathogen, the expression level of the tested genes was very low. The presence of A. alternata alone and in combination with bacteria increased the transcripts of all genes. Data showed a potential of best performing isolate Ps168 to sustain tomato plants nutrition and activate defense-related genes for protection by pathogenic fungi.201729079927
878570.9983Mechanism of resistance to Cucumber mosaic virus elicited by inoculation with Bacillus subtilis subsp. subtilis. BACKGROUND: Systemic resistance stimulated by rhizosphere bacteria is an important strategy for the management of plant viruses. The efficacy of Bacillus subtilis subsp. subtilis was assessed for protection of cucumber and Arabidopsis against Cucumber mosaic virus (CMV). Moreover, transcriptomic analysis was carried out for A. thaliana colonized with B. subtilis subsp. subtilis and infected with CMV. RESULTS: Treatment with a cell suspension of Bacillus revealed a significant reduction of CMV severity in comparison to their control. All Arabidopsis mutants treated with B. subtilis showed a clear reduction in CMV accumulation. Disease severity data and virus concentration titer measurements correlated with gene up-regulation in microarray and reverse transcription quantitative polymerase chain reaction (RT-qPCR) experiments. Bacillus treatment increased Arabidopsis growth characteristics (fresh and dry weights and number of leaflets) under pot conditions. The molecular mechanisms by which Bacillus activated resistance to CMV were investigated. Using the microarray hybridization technique, we were able to determine the mechanism of resistance elicited by B. subtilis against CMV. The transcriptomic analysis confirmed the up-regulation of more than 250 defense-related genes in Arabidopsis expressing induced systemic resistance (ISR). RT-qPCR results validated the overexpression of defense genes (YLS9 and PR1 in Arabidopsis and PR1 and LOX in cucumber), implying their important roles in the stimulated defense response. CONCLUSION: Through the study of microarray and RT-qPCR analyses, it can be concluded that the overexpression of pathogenesis-related genes was necessary to stimulate CMV defense in cucumber and Arabidopsis by B. subtilis subsp. subtilis. © 2021 Society of Chemical Industry.202234437749
894180.9983Salicylate reduces the antimicrobial activity of ciprofloxacin against extracellular Salmonella enterica serovar Typhimurium, but not against Salmonella in macrophages. OBJECTIVES: Salicylate, a potent inducer of the MarA activator in Salmonella enterica, is the principal metabolite of aspirin, which is often consumed for medicinal and cosmetic uses. Our research was aimed at testing if salicylate activates the mar regulon in macrophage-associated Salmonella (intracellular bacteria), and investigating its effects on bacterial susceptibility to ciprofloxacin extracellularly and intracellularly. METHODS: J774 macrophages were infected with S. enterica serovar Typhimurium (wild-type and marA null mutant), treated with ciprofloxacin with and without pre-exposure to salicylate, and the surviving bacteria were counted. Similar experiments were conducted with bacteria in broth (extracellular bacteria). Phe-Arg-beta-naphthylamide (PAbetaN) was added to investigate the role of efflux pumps in resistance. The transcriptional regulation of marRAB, acrAB and micF in extracellular and intracellular Salmonella Typhimurium with and without salicylate and ciprofloxacin was investigated using green fluorescent protein as a marker protein and quantitative real time PCR. RESULTS: Pre-exposure of Salmonella to salicylate increased the resistance of extracellular but not intracellular bacteria to ciprofloxacin, although salicylate stimulated the expression of mar genes in intracellular and extracellular bacteria. Using marA mutants and the inhibitor PAbetaN, we showed that the improved resistance in extracellular bacteria is derived from the induction of acrAB by salicylate, which is mediated by MarA. CONCLUSIONS: In intracellular bacteria, the expression of acrAB is already higher when compared with extracellular cells; therefore, salicylate does not result in significant acrAB induction intracellularly and subsequent resistance enhancement. Results show that conclusions raised from extracellular studies cannot be applied to intracellular bacteria, although the systems have similar functions.201020237076
894890.9983Effect of sub-lethal chemical disinfection on the biofilm forming ability, resistance to antibiotics and expression of virulence genes of Salmonella Enteritidis biofilm-surviving cells. Although disinfection procedures are widely implemented in food environments, bacteria can survive and present increased virulence/resistance. Since little is known about these phenomena regarding biofilms, this study aimed to investigate the effect of chemical disinfection on biofilm-derived cells of Salmonella Enteritidis. Using a reference strain (NCTC 13349) and a food isolate (350), biofilm susceptibility to benzalkonium chloride (BAC), sodium hypochlorite (SH) and hydrogen peroxide (HP) was evaluated and biofilms were exposed to sub-lethal concentrations of each disinfectant. Biofilm-derived cells were characterized for their biofilm forming ability, antibiotic resistance and expression of virulence-associated genes. Except for a few instances, disinfectant exposure did not alter antibiotic susceptibility. However, SH and HP exposure enhanced the biofilm forming ability of Salmonella Enteritidis NCTC 13349. After BAC and HP exposure, biofilm-derived cells presented a down-regulation of rpoS. Exposure to BAC also revealed an up-regulation of invA, avrA and csgD on Salmonella Enteritidis NCTC 13349. The results obtained suggest that biofilm-derived cells that survive disinfection may represent an increased health risk.202031997643
6209100.9983Evaluation of Mycobacterium tuberculosis genes involved in resistance to killing by human macrophages. A coinfection assay was developed to examine Mycobacterium tuberculosis genes suspected to be involved in resistance to killing by human macrophages. THP-1 macrophages were infected with a mixture of equal numbers of recombinant Mycobacterium smegmatis LR222 bacteria expressing an M. tuberculosis gene and wild-type M. smegmatis LR222 bacteria expressing the xylE gene. At various times after infection, the infected macrophages were lysed and the bacteria were plated. The resulting colonies were sprayed with catechol to determine the number of recombinant colonies and the number of xylE-expressing colonies. M. smegmatis bacteria expressing the M. tuberculosis glutamine synthetase A (glnA) gene or open reading frame Rv2962c or Rv2958c demonstrated significantly increased survival rates in THP-1 macrophages relative to those of xylE-expressing bacteria. M. smegmatis bacteria expressing M. tuberculosis genes for phospholipase C (plcA and plcB) or for high temperature requirement A (htrA) did not.200010603413
6753110.9982Survival 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.19938285661
6170120.9982Resistance and susceptibility of mice to bacterial infection. IV. Functional specificity in natural resistance to facultative intracellular bacteria. The effect of opsonic antibody on resistance of susceptibility of three strains of mice, C57Bl/10, BALB/c, and CBA to the intracellular bacteria Listeria monocytogenes, Salmonella typhimurium, and Brucella abortus was tested. Bacteria were opsonized by serum treatment before their injection into mice, or the mice were preimmunized by injection with alcohol killed bacteria which induces antibody without macrophage activation. Antibody did not increase the rate of clearance of Listeria from the bloodstream, nor did it affect the subsequent growth of that organism in the spleen and liver. Blood clearance of S. typhimurium and of B. abortus was increased by preopsonization with specific antibody, indicating that opsonins were a limiting factor in resistance to these two bacteria. However, neither opsonization before infection nor immunization with alcohol killed vaccines had any effect on the strain distribution of resistance/susceptibility, which differs for each of the three intracellular pathogens. Thus, even in the presence of adequate opsonization the three strains of mice showed different patterns of resistance/susceptibility to Listeria, S. typhimurium, and B. abortus. This implies that each has a unique cellular mechanism of early nonspecific resistance.19836413682
6208130.9982Identification of bistable populations of Porphyromonas gingivalis that differ in epithelial cell invasion. Bistable populations of bacteria give rise to two or more subtypes that exhibit different phenotypes. We have explored whether the periodontal pathogen Porphyromonas gingivalis exhibits bistable invasive phenotypes. Using a modified cell invasion assay, we show for the first time that there are two distinct subtypes within a population of P. gingivalis strains NCTC 11834 and W50 that display differences in their ability to invade oral epithelial cells. The highly invasive subtype invades cells at 10-30-fold higher levels than the poorly invasive subtype and remains highly invasive for approximately 12-16 generations. Analysis of the gingipain activity of these subtypes revealed that the highly invasive type had reduced cell-associated arginine-specific protease activity. The role of Arg-gingipain activity in invasion was verified by enhancement of invasion by rgpAB mutations and by inclusion of an Arg-gingipain inhibitor in invasion assays using wild-type bacteria. In addition, a population of ΔrgpAB bacteria did not contain a hyperinvasive subtype. Screening of the protease activity of wild-type populations of both strains identified high and low protease subtypes which also showed a corresponding reduction or enhancement, respectively, of invasive capabilities. Microarray analysis of these bistable populations revealed a putative signature set of genes that includes oxidative stress resistance and iron transport genes, and which might be critical to invasion of or survival within epithelial cells.201020576685
6752140.9982Isolation of radiation-resistant bacteria without exposure to irradiation. Resistance to desiccation was utilized in the selection of highly radiation-resistant asporogenous bacteria from non-irradiated sources. A bacterial suspension in phosphate buffer was dried in a thin film at 25 degrees C and 33% relative humidity. Storage under these conditions for 15 days or more reduced the number of radiation-sensitive bacteria. Further selection for radiation-resistant bacteria was obtained by irradiation of bacteria on velveteen in the replication process, thereby avoiding the toxic effect of irradiated media. The similarity of radiation resistance and identifying characteristics in irradiated and non-irradiated isolates should allay some concerns that highly radiation-resistant bacteria have been permanently altered by radiation selection.1979394680
6171150.9982Host response to infection with a temperature-sensitive mutant of Salmonella typhimurium in a susceptible and a resistant strain of mice. The inoculation of a temperature-sensitive mutant of Salmonella typhimurium induced a long-lasting infection in susceptible (C57BL/6) and resistant (A/J) mice. During week 1 of infection, the number of bacteria in the spleens was similar in both mouse strains. Then, the decrease of bacteria was more rapid in the resistant strain. Splenomegaly and granulomatous hepatitis were more severe in the susceptible strain. The immune response induced by this infection was studied. In both mouse strains delayed-type hypersensitivity to Salmonella antigens was present, and resistance to reinfection with a virulent strain of S. typhimurium or with Listeria monocytogenes appeared with the same kinetics. Thus, it does not seem that the gene(s) controlling natural resistance to S. typhimurium act(s) on acquired immunity.19853897053
8784160.9982Bacillus firmus Strain I-1582, a Nematode Antagonist by Itself and Through the Plant. Bacillus firmus I-1582 is approved in Europe for the management of Meloidogyne on vegetable crops. However, little information about its modes of action and temperature requirements is available, despite the effect of these parameters in its efficacy. The cardinal temperatures for bacterial growth and biofilm formation were determined. The bacteria was transformed with GFP to study its effect on nematode eggs and root colonization of tomato (Solanum lycopersicum) and cucumber (Cucumis sativus) by laser-scanning confocal microscopy. Induction of plant resistance was determined in split-root experiments and the dynamic regulation of genes related to jasmonic acid (JA) and salicylic acid (SA) by RT-qPCR at three different times after nematode inoculation. The bacteria was able to grow and form biofilms between 15 and 45°C; it degraded egg-shells and colonized eggs; it colonized tomato roots more extensively than cucumber roots; it induced systemic resistance in tomato, but not in cucumber; SA and JA related genes were primed at different times after nematode inoculation in tomato, but only the SA-related gene was up-regulated at 7 days after nematode inoculation in cucumber. In conclusion, B. firmus I-1582 is active at a wide range of temperatures; its optimal growth temperature is 35°C; it is able to degrade Meloidogyne eggs, and to colonize plant roots, inducing systemic resistance in a plant dependent species manner.202032765537
8955170.9982Increasing resistance of planktonic and biofilm cultures of Burkholderia cepacia to ciprofloxacin and ceftazidime during exponential growth. The change in resistance of Burkholderia cepacia to ceftazidime and to ciprofloxacin during the exponential phase and up to the onset of stationary phase was assessed along the growth curve in batch culture. B. cepacia was grown in planktonic culture and in a biofilm on a membrane support. Resistance increased progressively during the exponential phase, being increased by ten-fold about every four generations. Bacteria grown in a biofilm were about 15 times more resistant than equivalent planktonic-grown bacteria. The growth rate was not the key factor for the development of resistance. The growth phase and the mode of growth have a fundamental impact on the susceptibility of B. cepacia towards antimicrobial agents. Bacteria growing at the same rate may differ greatly in their resistance to antimicrobial agents.19989738832
6241180.9982Bactericidal activities of essential oils of basil and sage against a range of bacteria and the effect of these essential oils on Vibrio parahaemolyticus. Basil and sage essential oils were examined for bactericidal activity against a range of Gram-positive and Gram-negative bacteria by viable count determinations. Generally, Gram-positive bacteria showed higher resistance to basil and sage essential oils than Gram-negative bacteria. Vibrio species showed a high sensitivity to both essential oils. Stationary growth phase cells of selected bacteria showed higher resistance to these essential oils than exponential growth phase cells. Basil-resistant (b21) and sage-resistant (s20) strains of Vibrio parahaemolyticus were isolated. Both strains showed higher resistance to heat and H2O2 than parent strain. Conversely, heat-adapted V. parahaemolyticus also showed a higher resistance to these essential oils than nonadapted cells.199910652788
8889190.9982Differences in Gene Expression Profiles between Early and Late Isolates in Monospecies Achromobacter Biofilm. Bacteria of genus Achromobacter are emerging pathogens in cystic fibrosis (CF) capable of biofilm formation and development of antimicrobial resistance. Evolutionary adaptions in the transition from primary to chronic infection were assessed by transcriptomic analysis of successive isolates of Achromobacter xylosoxidans from a single CF patient. Several efflux pump systems targeting antimicrobial agents were upregulated during the course of the disease, whereas all genes related to motility were downregulated. Genes annotated to subsystems of sulfur metabolism, protein metabolism and potassium metabolism exhibited the strongest upregulation. K+ channel genes were hyperexpressed, and a putative sulfite oxidase was more than 1500 times upregulated. The transcriptome patterns indicated a pivotal role of sulfur metabolism and electrical signalling in Achromobacter biofilms during late stage CF lung disease.201728534862