# | Rank | Similarity | Title + Abs. | Year | PMID |
|---|---|---|---|---|---|
| 0 | 1 | 2 | 3 | 4 | 5 |
| 8976 | 0 | 0.9980 | Biosynthesis of H(2)S and Siderophores Targeting Gram-Negative Bacterial Resistance to Reactive Oxygen Species. Reactive oxygen species (ROS) are a promising alternative bactericide. However, it is questioned that bacteria can potentially develop resistance to ROS, similar to their resistance against antibiotics and silver. Herein, it is reported that Gram-negative bacteria, including Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae, develop resistance to ROS after six repeated exposures. Notably, ROS minimum inhibitory concentration of Pseudomonas aeruginosa significantly increases to 256-fold after ten passages. The resistance mechanism predominantly originates from the intensified biosynthesis of the highly reductive hydrogen sulfide (H(2)S) and pyoverdine (PVD) siderophores, effectively neutralizing ROS. Simultaneously, PVD transports Fe(3+) from the extracellular space into the bacteria, releasing H(2)S bound to Fe(3+) and enhancing ROS scavenging. Additionally, the enhanced outer membrane (OM) biogenesis establishes a robust OM barrier, impeding ROS penetration. The acquired resistance to ROS can be significantly reduced by incorporating additional Fe(3+) into the culture medium or disrupting the H(2)S biosynthetic gene. These observations suggest that careful consideration is required when utilizing ROS against Gram-negative bacteria. It is anticipated that understanding this resistance mechanism can inform the development of future antimicrobial agents, particularly for Gram-negative bacteria. | 2025 | 40948366 |
| 4741 | 1 | 0.9979 | Detection of antimicrobial resistance-associated proteins by titanium dioxide-facilitated intact bacteria mass spectrometry. Titanium dioxide-modified target plates were developed to enhance intact bacteria analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The plates were designed to photocatalytically destroy the bacterial envelope structure and improve the ionization efficiency of intracellular components, thereby promoting the measurable mass range and the achievable detection sensitivity. Accordingly, a method for rapid detection of antimicrobial resistance-associated proteins, conferring bacterial resistance against antimicrobial drugs, was established by mass spectrometric fingerprinting of intact bacteria without the need for any sample pre-treatment. With this method, the variations in resistance proteins' expression levels within bacteria were quickly measured from the relative peak intensities. This approach of resistance protein detection directly from intact bacteria by mass spectrometry is useful for fast discrimination of antimicrobial-resistant bacteria from their non-resistant counterparts whilst performing species identification. Also, it could be used as a rapid and convenient way for initial determination of the underlying resistance mechanisms. | 2018 | 29719694 |
| 315 | 2 | 0.9979 | Phosphorothioate DNA as an antioxidant in bacteria. Diverse bacteria contain DNA with sulfur incorporated stereo-specifically into their DNA backbone at specific sequences (phosphorothioation). We found that in vitro oxidation of phosphorothioate (PT) DNA by hydrogen peroxide (H(2)O(2)) or peracetic acid has two possible outcomes: DNA backbone cleavage or sulfur removal resulting in restoration of normal DNA backbone. The physiological relevance of this redox reaction was investigated by challenging PT DNA hosting Salmonella enterica cells using H(2)O(2). DNA phosphorothioation was found to correlate with increasing resistance to the growth inhibition by H(2)O(2). Resistance to H(2)O(2) was abolished when each of the three dnd genes, required for phosphorothioation, was inactivated. In vivo, PT DNA is more resistant to the double-strand break damage caused by H(2)O(2) than PT-free DNA. Furthermore, sulfur on the modified DNA was consumed and the DNA was converted to PT-free state when the bacteria were incubated with H(2)O(2). These findings are consistent with a hypothesis that phosphorothioation modification endows DNA with reducing chemical property, which protects the hosting bacteria against peroxide, explaining why this modification is maintained by diverse bacteria. | 2012 | 22772986 |
| 259 | 3 | 0.9979 | Dual-Plasmid Mini-Tn5 System to Stably Integrate Multicopy of Target Genes in Escherichia coli. The efficiency of valuable metabolite production by engineered microorganisms underscores the importance of stable and controllable gene expression. While plasmid-based methods offer flexibility, integrating genes into host chromosomes can establish stability without selection pressure. However, achieving site-directed multicopy integration presents challenges, including site selection and stability. We introduced a stable multicopy integration method by using a novel dual-plasmid mini-Tn5 system to insert genes into Escherichia coli's genome. The gene of interest was combined with a removable antibiotic resistance gene. After the selection of bacteria with inserted genes, the antibiotic resistance gene was removed. Optimizations yielded an integration efficiency of approximately 5.5 × 10(-3) per recipient cell in a single round. Six rounds of integration resulted in 19 and 5 copies of the egfp gene in the RecA(+) strain MG1655 and the RecA(-) strain XL1-Blue MRF', respectively. Additionally, we integrated a polyhydroxybutyrate (PHB) synthesis gene cluster into E. coli MG1655, yielding an 8-copy integration strain producing more PHB than strains with the cluster on a high-copy plasmid. The method was efficient in generating gene insertions in various E. coli strains, and the inserted genes were stable after extended culture. This stable, high-copy integration tool offers potential for diverse applications in synthetic biology. | 2024 | 39418641 |
| 390 | 4 | 0.9978 | A new simple method for introducing an unmarked mutation into a large gene of non-competent Gram-negative bacteria by FLP/FRT recombination. BACKGROUND: For the disruption of a target gene in molecular microbiology, unmarked mutagenesis is preferable to marked mutagenesis because the former method raises no concern about the polar effect and leaves no selection marker. In contrast to naturally competent bacteria, there is no useful method for introducing an unmarked mutation into a large gene of non-competent bacteria. Nevertheless, large genes encoding huge proteins exist in diverse bacteria and are interesting and important for physiology and potential applications. Here we present a new method for introducing an unmarked mutation into such large genes of non-competent Gram-negative bacteria. RESULTS: Two gene replacement plasmids, pJQFRT and pKFRT/FLP, were constructed to apply the FLP/FRT recombination system to introduce an unmarked mutation into a large gene of non-competent Gram-negative bacteria. In our methodology, pJQFRT and pKFRT/FLP are integrated into the upstream and the downstream regions of a target gene, respectively, through homologous recombination. The resultant mutant has antibiotic resistance markers, the sacB counter-selection marker, flp recombinase under the control of the tetR regulator, and identical FRT sites sandwiching the target gene and the markers on its chromosome. By inducing the expression of flp recombinase, the target gene is completely deleted together with the other genes derived from the integrated plasmids, resulting in the generation of an unmarked mutation. By this method, we constructed an unmarked mutant of ataA, which encodes the huge trimeric autotransporter adhesin (3,630 aa), in a non-competent Gram-negative bacterium, Acinetobacter sp. Tol 5. The unmarked ataA mutant showed the same growth rate as wild type Tol 5, but lost the adhesive properties of Tol 5, similar to the transposon-inserted mutant of ataA that we generated previously. CONCLUSIONS: The feasibility of our methodology was evidenced by the construction of an unmarked ataA mutant in the Tol 5 strain. Since FLP/FRT recombination can excise a long region of DNA exceeding 100 kb, our method has the potential to selectively disrupt much larger genes or longer regions of gene clusters than ataA. Our methodology allows the straightforward and efficient introduction of an unmarked mutation into a large gene or gene cluster of non-enterobacterial Gram-negative bacteria. | 2013 | 23594401 |
| 385 | 5 | 0.9978 | Introduction of a mini-gene encoding a five-amino acid peptide confers erythromycin resistance on Bacillus subtilis and provides temporary erythromycin protection in Proteus mirabilis. A 15-bp mini-gene was introduced into Bacillus subtilis and into stable protoplast-like L-forms of Proteus mirabilis. This mini-gene encoded the peptide MVLFV and modeled a fragment of Escherichia coli 23S rRNA responsible for E. coli erythromycin (Ery) resistance. Expression of the introduced mini-gene conferred permanent Ery resistance on B. subtilis. In L-forms of P. mirabilis, the Ery-protective effect was maintained in the course of several generations. Herewith, the mechanism of Ery resistance mediated by expression of specific short peptides was shown to exist in evolutionary distant bacteria. Three new plasmids were constructed containing the gene under study transcriptionally fused with the genes encoding glutamylendopeptidase of Bacillus licheniformis or delta-endotoxin of Bacillus thuringiensis. The Ery resistance pentapeptide (E-peptide) mini-gene served as an efficient direct transcriptional reporter and allowed to select bacillar glutamylendopeptidase with improved productivity. The mini-genes encoding E-peptides may be applied as selective markers to transform both Gram-positive and Gram-negative bacteria. The small size of the E-peptide mini-genes makes them attractive selective markers for vector construction. | 2000 | 10620668 |
| 651 | 6 | 0.9977 | A simple method to generate chromosomal mutations in Lactobacillus plantarum strain TF103 to eliminate undesired fermentation products. Gram-positive bacteria have been explored to convert lignocellulosic biomass to biofuel and bioproducts. Our long-term goal is to create genetically engineered lactic acid bacteria (LAB) strains that convert agricultural biomass into ethanol and other value-added products. The immediate approaches toward this goal involve genetic manipulations by either introducing ethanol production pathway genes or inactivating pathways genes that lead to production of undesired byproducts. The widely studied species Lactobacillus plantarum is now considered a model for genetic manipulations of LAB. In this study, L. plantarum TF103 strain, in which two of the chromosomal L-ldh and D-ldh genes are inactivated, was used to introduce additional mutations on the chromosome to eliminate undesired fermentation products. We targeted the acetolactate synthase gene (als) that converts pyruvate to acetolactate, to eliminate the production of acetoin and 2,3-butanodial. A pBluescript derivative containing sections of the als coding region and an erythromycin resistance gene was directly introduced into L. plantarum TF103 cells to create mutations under selection pressure. The resulting erythromycin resistant (Em(r)) TF103 strain appears to have chromosomal mutations of both the als and the adjacent lysP genes as revealed by polymerase chain reaction and Southern blot analyses. Mutations were thus generated via targeted homologous recombination using a Gram-negative cloning vector, eliminating the use of a shuttle vector. This method should facilitate research in targeted inactivation of other genes in LAB. | 2006 | 18563659 |
| 652 | 7 | 0.9977 | A simple method to generate chromosomal mutations in Lactobacillus plantarum strain TF103 to eliminate undesired fermentation products. Gram-positive bacteria have been explored to convert lignocellulosic biomass to biofuel and bioproducts. Our long-term goal is to create genetically engineered lactic acid bacteria (LAB) strains that convert agricultural biomass into ethanol and other value-added products. The immediate approaches toward this goal involve genetic manipulations by either introducing ethanol production pathway genes or inactivating pathways genes that lead to production of undesired byproducts. The widely studied species Lactobacillus plantarum is now considered a model for genetic manipulations of LAB. In this study, L. plantarum TF103 strain, in which two of the chromosomal L-ldh and D-ldh genes are inactivated, was used to introduce additional mutations on the chromosome to eliminate undesired fermentation products. We targeted the acetolactate synthase gene (als) that converts pyruvate to acetolactate, to eliminate the production of acetoin and 2,3-butanodial. A pBluescript derivative containing sections of the als coding region and an erythromycin resistance gene was directly introduced into L. plantarum TF103 cells to create mutations under selection pressure. The resulting erythromycin resistant (Emr) TF103 strain appears to have chromosomal mutations of both the als and the adjacent lysP genes as revealed by polymerase chain reaction and Southern blot analyses. Mutations were thus generated via targeted homologous recombination using a Gram-negative cloning vector, eliminating the use of a shuttle vector. This method should facilitate research in targeted inactivation of other genes in LAB. | 2006 | 16915693 |
| 6311 | 8 | 0.9977 | Development of an antibiotic marker-free platform for heterologous protein production in Streptomyces. BACKGROUND: The industrial use of enzymes produced by microorganisms is continuously growing due to the need for sustainable solutions. Nevertheless, many of the plasmids used for recombinant production of proteins in bacteria are based on the use of antibiotic resistance genes as selection markers. The safety concerns and legal requirements surrounding the increased use of antibiotic resistance genes have made the development of new antibiotic-free approaches essential. RESULTS: In this work, a system completely free of antibiotic resistance genes and useful for the production of high yields of proteins in Streptomyces is described. This system is based on the separation of the two components of the yefM/yoeBsl (antitoxin/toxin) operon; the toxin (yoeBsl) gene, responsible for host death, is integrated into the genome and the antitoxin gene (yefMsl), which inactivates the toxin, is located in the expression plasmid. To develop this system, the toxin gene was integrated into the genome of a strain lacking the complete operon, and the antibiotic resistance gene integrated along with the toxin was eliminated by Cre recombinase to generate a final host strain free of any antibiotic resistance marker. In the same way, the antibiotic resistance gene from the final expression plasmid was removed by Dre recombinase. The usefulness of this system was analysed by checking the production of two hydrolases from different Streptomyces. Production of both proteins, with potential industrial use, was high and stable over time after strain storage and after serial subcultures. These results support the robustness and stability of the positive selection system developed. CONCLUSIONS: The total absence of antibiotic resistance genes makes this system a powerful tool for using Streptomyces as a host to produce proteins at the industrial level. This work is the first Streptomyces antibiotic marker-free system to be described. Graphical abstract Antibiotic marker-free platform for protein expression in Streptomyces. The antitoxin gene present in the expression plasmid counteracts the effect of the toxin gene in the genome. In absence of the expression plasmid, the toxin causes cell death ensuring that only plasmid-containing cells persist. | 2017 | 28950904 |
| 4740 | 9 | 0.9977 | Resensitization of Multi Drug-Resistant Aeromonas caviae with Exogenous Hydrogen Sulfide Potentiated Antibiotics. Antimicrobial resistance (AMR) is a growing public health threat caused by the widespread overuse of antibiotics. Bacteria with antibiotic resistance may acquire resistance genes from soil or water. Endogenous hydrogen sulfide (H(2)S) production in bacteria confers antibiotic tolerance in many, suggesting a universal defense mechanism against antibiotics. In this study, we isolated and identified soil-based antibiotic-resistant bacteria collected from contaminated areas. An antibiotic-resistant bacterium was identified as non-endogenous-H(2)S-producing, allowing us to examine the effect of exogenous H(2)S on its resistance mechanism. Therefore, we demonstrated that different classes of antibiotic resistance can be reverted by employing H(2)S with antibiotics like ampicillin and gentamicin. Methods like Kirby-Bauer Disk-Diffusion, Scanning Electron Microscopy, and Flow Cytometer analysis were performed to assess the antibacterial activity of H(2)S with ampicillin and gentamicin. The antioxidative efficiency of H(2)S was evaluated using the DCFH-DA (ROS) test, as well as lipid peroxidation, and LDH activity. These were further confirmed with enzymatic and non-enzymatic (SOD, CAT, GST, and GSH) antioxidant studies. These findings support H(2)S as an antibiotic-potentiator, causing bacterial membrane damage, oxidative stress, and disrupting DNA and proteins. Thus, supplying exogenous H(2)S can be a good agent for the reversal of Antibiotic resistance. | 2024 | 39579197 |
| 8847 | 10 | 0.9977 | Phage-delivered sensitisation with subsequent antibiotic treatment reveals sustained effect against antimicrobial resistant bacteria. Temperate phages integrated with clustered regularly interspaced short palindromic repeat (CRISPR)/Cas systems have been gaining attention as potential strategies for combating bacteria resistant to antimicrobials. To further advance this technology, phage recombination procedure should be improved, and the bactericidal effect should be examined in detail and compared with conventional lytic phage strategy. The possibility of the emergence of mutational resistance, a phenomenon commonly observed with lytic phage therapy, should be illustrated. Methods: Here, we developed a novel one-step cloning method to fulfil the recombination of CRISPR/Cas9 system within the genome of a new isolated lysogenic Escherichia coli phage. Then, we proposed and developed a phage-delivered resistance eradication with subsequent antibiotic treatment (PRESA) strategy. The removal efficiency and antimicrobial effect of the plasmids were analysed. Long-term antimicrobial effect was evaluated by continued OD(600) monitoring for 240 hours to illustrate the potential mutational resistance, compared with the lytic phage strategy. The treatment effect of PRESA was evaluated in vivo by determining bacterial loads in the skin and intestine of infected mice, in contrast with lytic phage therapy. Genome sequencing was performed to identify mutations in bacterial cells treated with phage strategies. Results: Phage-delivered CRISPR targeting efficiently eradicated and blocked the transfer of the antibiotic resistance plasmid. PRESA decreased the bacterial load by over 6- and 5-logs in vitro and in vivo, respectively. Importantly, while lytic phages induced mutational phage resistance at 24 h in vitro and 48 hours in vivo, PRESA demonstrated a constant effect and revealed no resistant mutants. Genes involved in DNA mismatch repair were upregulated in cells undergoing Cas9-based plasmid cleavage, which may reduce the development of mutations. Conclusion: The PRESA strategy for eradicating resistant bacteria showed high bactericidal efficacy and a sustained inhibition effect against resistant bacteria. By restoring the efficacy of low-cost antibiotics, PRESA could be developed as an efficient and economical therapy for infections of antibiotic resistant bacteria. | 2020 | 32483454 |
| 314 | 11 | 0.9977 | Characterization of mercury bioremediation by transgenic bacteria expressing metallothionein and polyphosphate kinase. BACKGROUND: The use of transgenic bacteria has been proposed as a suitable alternative for mercury remediation. Ideally, mercury would be sequestered by metal-scavenging agents inside transgenic bacteria for subsequent retrieval. So far, this approach has produced limited protection and accumulation. We report here the development of a transgenic system that effectively expresses metallothionein (mt-1) and polyphosphate kinase (ppk) genes in bacteria in order to provide high mercury resistance and accumulation. RESULTS: In this study, bacterial transformation with transcriptional and translational enhanced vectors designed for the expression of metallothionein and polyphosphate kinase provided high transgene transcript levels independent of the gene being expressed. Expression of polyphosphate kinase and metallothionein in transgenic bacteria provided high resistance to mercury, up to 80 μM and 120 μM, respectively. Here we show for the first time that metallothionein can be efficiently expressed in bacteria without being fused to a carrier protein to enhance mercury bioremediation. Cold vapor atomic absorption spectrometry analyzes revealed that the mt-1 transgenic bacteria accumulated up to 100.2 ± 17.6 μM of mercury from media containing 120 μM Hg. The extent of mercury remediation was such that the contaminated media remediated by the mt-1 transgenic bacteria supported the growth of untransformed bacteria. Cell aggregation, precipitation and color changes were visually observed in mt-1 and ppk transgenic bacteria when these cells were grown in high mercury concentrations. CONCLUSION: The transgenic bacterial system described in this study presents a viable technology for mercury bioremediation from liquid matrices because it provides high mercury resistance and accumulation while inhibiting elemental mercury volatilization. This is the first report that shows that metallothionein expression provides mercury resistance and accumulation in recombinant bacteria. The high accumulation of mercury in the transgenic cells could present the possibility of retrieving the accumulated mercury for further industrial applications. | 2011 | 21838857 |
| 262 | 12 | 0.9976 | Genome scanning in Haemophilus influenzae for identification of essential genes. We have developed a method for identifying essential genes by using an in vitro transposition system, with a small (975 bp) insertional element containing an antibiotic resistance cassette, and mapping these inserts relative to the deduced open reading frames of Haemophilus influenzae by PCR and Southern analysis. Putative essential genes are identified by two methods: mutation exclusion or zero time analysis. Mutation exclusion consists of growing an insertional library and identifying open reading frames that do not contain insertional elements: in a growing population of bacteria, insertions in essential genes are excluded. Zero time analysis consists of monitoring the fate of individual insertions after transformation in a growing culture: the loss of inserts in essential genes is observed over time. Both methods of analysis permit the identification of genes required for bacterial survival. Details of the mutant library construction and the mapping strategy, examples of mutant exclusion, and zero time analysis are presented. | 1999 | 10438768 |
| 9053 | 13 | 0.9976 | Nordihydroguaiaretic acid reverses the antibacterial activity of colistin against MCR-1-positive bacteria in vivo/in vitro by inhibiting MCR-1 activity and injuring the bacterial cell membrane. BACKGROUND: Colistin (polymyxin E) is an effective antibiotic for the treatment of most multidrug-resistant Gram-negative bacteria. However, some bacteria, including bacterial spp. belonging to the Enterobacteriaceae family, have an acquired resistance against polymyxins, which is attributed to they possess plasmid-carried resistance genes (mcr-1 and its variants). So, there is an urgent need to develop new therapeutic strategies to target broad spectrum resistant spp. from Enterobacteriaceae family in response to the loss of the protective barrier of last-line antibiotics. Here, we report the adjuvant capacity of nordihydroguaiaretic acid (NDGA) for restoring the antibacterial activity of colistin against MCR-1-positive E. coli ZJ487 in vivo/in vitro. METHODS: A checkerboard assay, time-killing analysis, isobolograms, growth curves and inducible resistance test showed the effect of NDGA combined with colistin in vitro. TLC was used to detect the inhibitory effect of NDGA on MCR-1. Colony determination and hematoxylin and eosin (HE) staining were used to assess the synergistic effect of NDGA and colistin in mice. RESULTS: Our results showed that NDGA in combination with colistin showed a synergistic bactericidal action without inducing resistance. NDGA directly inhibited MCR-1 activity and resulted in measurable injury to the bacterial cell membrane to recover the antibacterial effect of colistin. Most importantly, NDGA in combination with colistin exhibited an in vivo synergistic effect in murine peritonitis infection models, as evidenced by the survival rate of MCR-1-positive E. coli ZJ487-infected mice which increased from 6.67 to 50.0%. CONCLUSION: Our study demonstrated that NDGA effectively rescues the efficiency of colistin against MCR-positive E. coli ZJ487 by simultaneously inhibiting both, the MCR activity and the injury to the cell membrane of bacteria. | 2022 | 35158237 |
| 9297 | 14 | 0.9976 | Xer recombination for the automatic deletion of selectable marker genes from plasmids in enteric bacteria. Antibiotic resistance genes are widely used to select bacteria transformed with plasmids and to prevent plasmid loss from cultures, yet antibiotics represent contaminants in the biopharmaceutical manufacturing process, and retaining antibiotic resistance genes in vaccines and biological therapies is discouraged by regulatory agencies. To overcome these limitations, we have developed X-mark™, a novel technology that leverages Xer recombination to generate selectable marker gene-free plasmids for downstream therapeutic applications. Using this technique, X-mark plasmids with antibiotic resistance genes flanked by XerC/D target sites are generated in Escherichia coli cytosol aminopeptidase (E. coli pepA) mutants, which are deficient in Xer recombination on plasmids, and subsequently transformed into enteric bacteria with a functional Xer system. This results in rapid deletion of the resistance gene at high resolution (100%) and stable replication of resolved plasmids for more than 40 generations in the absence of antibiotic selective pressure. This technology is effective in both Escherichia coli and Salmonella enterica bacteria due to the high degree of homology between accessory sequences, including strains that have been developed as oral vaccines for clinical use. X-mark effectively eliminates any regulatory and safety concerns around antibiotic resistance carryover in biopharmaceutical products, such as vaccines and therapeutic proteins. Graphical Abstract. | 2022 | 35601876 |
| 9092 | 15 | 0.9976 | Antimicrobial and Antiviral Nanofibers Halt Co-Infection Spread via Nuclease-Mimicry and Photocatalysis. The escalating spread of drug-resistant bacteria and viruses is a grave concern for global health. Nucleic acids dominate the drug-resistance and transmission of pathogenic microbes. Here, imidazolium-type poly(ionic liquid)/porphyrin (PIL-P) based electrospun nanofibrous membrane and its cerium (IV) ion complex (PIL-P-Ce) are developed. The obtained PIL-P-Ce membrane exhibits high and stable efficiency in eradicating various microorganisms (bacteria, fungi, and viruses) and decomposing microbial antibiotic resistance genes and viral nucleic acids under light. The nuclease-mimetic and photocatalytic mechanisms of the PIL-P-Ce are elucidated. Co-infection wound models in mice with methicillin-resistant S. aureus and hepatitis B virus demonstrate that PIL-P-Ce integrate the triple effects of cationic polymer, photocatalysis, and nuclease-mimetic activities. As revealed by proteomic analysis, PIL-P-Ce shows minimal phototoxicity to normal tissues. Hence, PIL-P-Ce has potential as a "green" wound dressing to curb the spread of drug-resistant bacteria and viruses in clinical settings. | 2024 | 38647392 |
| 9093 | 16 | 0.9976 | Antibacterial activity of positively charged carbon quantum dots without detectable resistance for wound healing with mixed bacteria infection. Widespread bacterial infection and the spread of antibiotic resistance exhibit increasing threat to the public and thus require new antibacterial strategies. Carbon quantum dots (CQDs) have been extensively investigated to play fluorescent, catalytic roles and even potential biomedical functions containing sterilization. However, synthetic understanding of the interaction of CQDs and bacteria, the exhibition of antibacterial ability, and the risk of resistance evolution remain lacking. Herein, a simple one-pot method was fabricated to prepare positively charged CQDs (PC-CQDs) as a broad-spectrum antibacterial agent. PC-CQDs possessed effective antibacterial activity against all tested Gram-positive, Gram-negative, and drug-resistant bacteria. Investigation of the antibacterial mechanism of PC-CQDs indicated that small-sized PC-CQDs functionalized with -NH(2) and -NH induced strong adherence behavior on the bacterial cell membrane. Moreover, the entry of PC-CQDs caused conformational changes in the genes and generation of reactive oxygen species in the bacteria. Safety evaluation illustrated that PC-CQDs did not trigger detectable drug resistance or hemolysis. Furthermore, PC-CQDs effectively promoted the antibacterial treatment of mixed Staphylococcus aureus and Escherichia coli infected wound in rats with low in vivo toxicity. These results suggested that PC-CQDs are a potential antibacterial candidate for real wound healing applications in complex bacterial infections and even resistant bacteria-caused infections. | 2021 | 33812599 |
| 4778 | 17 | 0.9976 | DNA extraction of microbial DNA directly from infected tissue: an optimized protocol for use in nanopore sequencing. Identification of bacteria causing tissue infections can be comprehensive and, in the cases of non- or slow-growing bacteria, near impossible with conventional methods. Performing shotgun metagenomic sequencing on bacterial DNA extracted directly from the infected tissue may improve time to diagnosis and targeted treatment considerably. However, infected tissue consists mainly of human DNA (hDNA) which hampers bacterial identification. In this proof of concept study, we present a modified version of the Ultra-Deep Microbiome Prep kit for DNA extraction procedure, removing additional human DNA. Tissue biopsies from 3 patients with orthopedic implant-related infections containing varying degrees of Staphylococcus aureus were included. Subsequent DNA shotgun metagenomic sequencing using Oxford Nanopore Technologies' (ONT) MinION platform and ONTs EPI2ME WIMP and ARMA bioinformatic workflows for microbe and antibiotic resistance genes identification, respectively. The modified DNA extraction protocol led to an additional ~10-fold reduction of human DNA while preserving S. aureus DNA. Including the DNA sequencing and bioinformatics analyses, the presented protocol has the potential of identifying the infection-causing pathogen in infected tissue within 7 hours after biopsy. However, due to low number of S. aureus reads, positive identification of antibiotic resistance genes was not possible. | 2020 | 32076089 |
| 9212 | 18 | 0.9976 | Review of knockout technology approaches in bacterial drug resistance research. Gene knockout is a widely used method in biology for investigating gene function. Several technologies are available for gene knockout, including zinc-finger nuclease technology (ZFN), suicide plasmid vector systems, transcription activator-like effector protein nuclease technology (TALEN), Red homologous recombination technology, CRISPR/Cas, and others. Of these, Red homologous recombination technology, CRISPR/Cas9 technology, and suicide plasmid vector systems have been the most extensively used for knocking out bacterial drug resistance genes. These three technologies have been shown to yield significant results in researching bacterial gene functions in numerous studies. This study provides an overview of current gene knockout methods that are effective for genetic drug resistance testing in bacteria. The study aims to serve as a reference for selecting appropriate techniques. | 2023 | 37605748 |
| 8963 | 19 | 0.9976 | Photodynamic therapy on mRNA levels in bacteria. Antimicrobial photodynamic therapy (aPDT) has shown efficacy in inactivating different bacterial species by photosensitizer-induced free radical production. Despite aPDT is considered unable to cause resistant strains, enzymatic pathways for detoxification of reactive oxygen species and transmembrane photosensitizer efflux systems could cause resistance to aPDT. Resistance mechanisms can be evaluated by measurement of mRNA from by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Thus, the aim of this study was to access the mRNA level data obtained by RT-qPCR in bacterial cells submitted to photodynamic therapy. Studies performed on mRNA levels in bacteria after PDT were assessed on MEDLINE/Pubmed. The mRNA levels from genes related to various functions have been successfully evaluated in both Gram-positive and -negative bacteria after aPDT by RT-qPCR. Such an approach has improved the understanding of aPDT-induced effects, and reinforced the effectiveness of aPDT on bacteria, which can cause infections in different human tissues. | 2024 | 39214913 |