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Scientific Reports Jun 2024Rhizoctonia solani, the causal agent of banded leaf and sheath blight (BL&SB), poses a significant threat to maize and various crops globally. The increasing concerns...
Rhizoctonia solani, the causal agent of banded leaf and sheath blight (BL&SB), poses a significant threat to maize and various crops globally. The increasing concerns surrounding the environmental and health impacts of chemical fungicides have encouraged intensified concern in the development of biological control agents (BCAs) as eco-friendly alternatives. In this study, we explored the potential of 22 rhizobacteria strains (AS1-AS22) isolates, recovered from the grasslands of the Pithoragarh region in the Central Himalayas, as effective BCAs against BL&SB disease. Among these strains, two Pseudomonas isolates, AS19 and AS21, exhibited pronounced inhibition of fungal mycelium growth in vitro, with respective inhibition rates of 57.04% and 54.15% in cell cultures and 66.56% and 65.60% in cell-free culture filtrates. Additionally, both strains demonstrated effective suppression of sclerotium growth. The strains AS19 and AS21 were identified as Pseudomonas sp. by 16S rDNA phylogeny and deposited under accession numbers NAIMCC-B-02303 and NAIMCC-B-02304, respectively. Further investigations revealed the mechanisms of action of AS19 and AS21, demonstrating their ability to induce systemic resistance (ISR) and exhibit broad-spectrum antifungal activity against Alternaria triticina, Bipolaris sorokiniana, Rhizoctonia maydis, and Fusarium oxysporum f. sp. lentis. Pot trials demonstrated significant reductions in BL&SB disease incidence (DI) following foliar applications of AS19 and AS21, with reductions ranging from 25 to 38.33% compared to control treatments. Scanning electron microscopy revealed substantial degradation of fungal mycelium by the strains, accompanied by the production of hydrolytic enzymes. These findings suggest the potential of Pseudomonas strains AS19 and AS21 as promising BCAs against BL&SB and other fungal pathogens. However, further field trials are warranted to validate their efficacy under natural conditions and elucidate the specific bacterial metabolites responsible for inducing systemic resistance. This study contributes to the advancement of sustainable disease management strategies and emphasizes the potential of Pseudomonas strains AS19 and AS21 in combating BL&SB and other fungal diseases affecting agricultural crops.
Topics: Plant Diseases; Zea mays; Pseudomonas; Rhizoctonia; Plant Leaves; Biological Control Agents; Pest Control, Biological; Antibiosis; Phylogeny
PubMed: 38866928
DOI: 10.1038/s41598-024-64028-1 -
PloS One 2024Evaluate the effects of five disinfection methods on bacterial concentrations in hospital sink drains, focusing on three opportunistic pathogens (OPs): Serratia...
OBJECTIVE
Evaluate the effects of five disinfection methods on bacterial concentrations in hospital sink drains, focusing on three opportunistic pathogens (OPs): Serratia marcescens, Pseudomonas aeruginosa and Stenotrophomonas maltophilia.
DESIGN
Over two years, three sampling campaigns were conducted in a neonatal intensive care unit (NICU). Samples from 19 sink drains were taken at three time points: before, during, and after disinfection. Bacterial concentration was measured using culture-based and flow cytometry methods. High-throughput short sequence typing was performed to identify the three OPs and assess S. marcescens persistence after disinfection at the genotypic level.
SETTING
This study was conducted in a pediatric hospitals NICU in Montréal, Canada, which is divided in an intensive and intermediate care side, with individual rooms equipped with a sink.
INTERVENTIONS
Five treatments were compared: self-disinfecting drains, chlorine disinfection, boiling water disinfection, hot tap water flushing, and steam disinfection.
RESULTS
This study highlights significant differences in the effectiveness of disinfection methods. Chlorine treatment proved ineffective in reducing bacterial concentration, including the three OPs. In contrast, all other drain interventions resulted in an immediate reduction in culturable bacteria (4-8 log) and intact cells (2-3 log). Thermal methods, particularly boiling water and steam treatments, exhibited superior effectiveness in reducing bacterial loads, including OPs. However, in drains with well-established bacterial biofilms, clonal strains of S. marcescens recolonized the drains after heat treatments.
CONCLUSIONS
Our study supports thermal disinfection (>80°C) for pathogen reduction in drains but highlights the need for additional trials and the implementation of specific measures to limit biofilm formation.
Topics: Serratia marcescens; Intensive Care Units, Neonatal; Disinfection; Humans; Pseudomonas aeruginosa; Infant, Newborn; Stenotrophomonas maltophilia; Serratia Infections; Cross Infection
PubMed: 38865328
DOI: 10.1371/journal.pone.0304378 -
Microbial Biotechnology Jun 2024Treating plant bacterial diseases is notoriously difficult because of the lack of available antimicrobials. Pseudomonas syringae pathovar syringae (Pss) is a major...
Treating plant bacterial diseases is notoriously difficult because of the lack of available antimicrobials. Pseudomonas syringae pathovar syringae (Pss) is a major pathogen of cherry (Prunus avium) causing bacterial canker of the stem, leaf and fruit, impacting productivity and leading to a loss of trees. In an attempt to find a treatment for this disease, naturally occurring bacteriophage (phage) that specifically target Pss is being investigated as a biocontrol strategy. However, before using them as a biocontrol treatment, it is important to both understand their efficacy in reducing the bacterial population and determine if the bacterial pathogens can evolve resistance to evade phage infection. To investigate this, killing curve assays of five MR phages targeting Pss showed that phage resistance rapidly emerges in vitro, even when using a cocktail of the five phages together. To gain insight to the changes occurring, Pss colonies were collected three times during a 66-h killing curve assay and separately, Pss and phage were also coevolved over 10 generations, enabling the measurement of genomic and fitness changes in bacterial populations. Pss evolved resistance to phages through modifications in lipopolysaccharide (LPS) synthesis pathways. Bacterial fitness (growth) and virulence were affected in only a few mutants. Deletion of LPS-associated genes suggested that LPS was the main target receptor for all five MR phages. Later generations of coevolved phages from the coevolution experiment were more potent at reducing the bacterial density and when used with wild-type phages could reduce the emergence of phage-resistant mutants. This study shows that understanding the genetic mechanisms of bacterial pathogen resistance to phages is important for helping to design a more effective approach to kill the bacteria while minimizing the opportunity for phage resistance to manifest.
Topics: Pseudomonas syringae; Plant Diseases; Pseudomonas Phages; Bacteriophages
PubMed: 38864499
DOI: 10.1111/1751-7915.14489 -
Microbial Biotechnology Jun 2024Antimicrobial resistance (AMR) is an escalating global health crisis, driven by the overuse and misuse of antibiotics. Multidrug-resistant Gram-negative bacteria, such...
Antimicrobial resistance (AMR) is an escalating global health crisis, driven by the overuse and misuse of antibiotics. Multidrug-resistant Gram-negative bacteria, such as Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae, are particularly concerning due to their high morbidity and mortality rates. In this context, endolysins, derived from bacteriophages, offer a promising alternative to traditional antibiotics. This study introduces LysJEP8, a novel endolysin derived from Escherichia phage JEP8, which exhibits remarkable antimicrobial activity against key Gram-negative members of the ESKAPE group. Comparative assessments highlight LysJEP8's superior performance in reducing bacterial survival rates compared to previously described endolysins, with the most significant impact observed against P. aeruginosa, and notable effects on A. baumannii and K. pneumoniae. The study found that LysJEP8, as predicted by in silico analysis, worked best at lower pH values but lost its effectiveness at salt concentrations close to physiological levels. Importantly, LysJEP8 exhibited remarkable efficacy in the disruption of P. aeruginosa biofilms. This research underscores the potential of LysJEP8 as a valuable candidate for the development of innovative antibacterial agents, particularly against Gram-negative pathogens, and highlights opportunities for further engineering and optimization to address AMR effectively.
Topics: Endopeptidases; Drug Resistance, Multiple, Bacterial; Anti-Bacterial Agents; Gram-Negative Bacteria; Pseudomonas aeruginosa; Biofilms; Microbial Sensitivity Tests; Bacteriophages; Klebsiella pneumoniae; Hydrogen-Ion Concentration; Acinetobacter baumannii; Microbial Viability
PubMed: 38864495
DOI: 10.1111/1751-7915.14483 -
Scientific Reports Jun 2024The Increase in infections caused by resistant strains of Pseudomonas aeruginosa poses a formidable challenge to global healthcare systems. P. aeruginosa is capable of...
The Increase in infections caused by resistant strains of Pseudomonas aeruginosa poses a formidable challenge to global healthcare systems. P. aeruginosa is capable of causing severe human infections across diverse anatomical sites, presenting considerable therapeutic obstacles due to its heightened drug resistance. Niosomal drug delivery systems offer enhanced pharmaceutical potential for loaded contents due to their desirable properties, mainly providing a controlled-release profile. This study aimed to formulate an optimized niosomal drug delivery system incorporating stearylamine (SA) to augment the anti-bacterial and anti-biofilm activities of quercetin (QCT) against both standard and clinical strains of P. aeruginosa. QCT-loaded niosome (QCT-niosome) and QCT-loaded SA- niosome (QCT-SA- niosome) were synthesized by the thin-film hydration technique, and their physicochemical characteristics were evaluated by field emission scanning electron microscopy (FE-SEM), zeta potential measurement, entrapment efficacy (EE%), and in vitro release profile. The anti-P. aeruginosa activity of synthesized niosomes was assessed using minimum inhibitory and bactericidal concentrations (MICs/MBCs) and compared with free QCT. Additionally, the minimum biofilm inhibitory and eradication concentrations (MBICs/MBECs) were carried out to analyze the ability of QCT-niosome and QCT-SA-niosome against P. aeruginosa biofilms. Furthermore, the cytotoxicity assay was conducted on the L929 mouse fibroblasts cell line to evaluate the biocompatibility of the formulated niosomes. FE-SEM analysis revealed that both synthesized niosomal formulations exhibited spherical morphology with different sizes (57.4 nm for QCT-niosome and 178.9 nm for QCT-SA-niosome). The EE% for cationic and standard niosomal formulations was reported at 75.9% and 59.6%, respectively. Both formulations showed an in vitro sustained-release profile, and QCT-SA-niosome exhibited greater stability during a 4-month storage time compared to QCT-niosome. Microbial experiments indicated that both prepared formulations had higher anti-bacterial and anti-biofilm activities than free QCT. Also, the QCT-SA-niosome exhibited greater reductions in MIC, MBC, MBIC, and MBEC values compared to the QCT-niosome at equivalent concentrations. This study supports the potential of QCT-niosome and QCT-SA-niosome as effective agents against P. aeruginosa infections, manifesting significant anti-bacterial and anti-biofilm efficacy alongside biocompatibility with L929 cell lines. Furthermore, our results suggest that optimized QCT-niosome with cationic lipids could efficiently target P. aeruginosa cells with negligible cytotoxic effect.
Topics: Pseudomonas aeruginosa; Liposomes; Quercetin; Animals; Biofilms; Mice; Anti-Bacterial Agents; Drug Delivery Systems; Pseudomonas Infections; Microbial Sensitivity Tests; Cations; Humans; Lipids; Cell Line; Amines
PubMed: 38862754
DOI: 10.1038/s41598-024-64416-7 -
PLoS Genetics Jun 2024Bacteria use diverse strategies and molecular machinery to maintain copper homeostasis and to cope with its toxic effects. Some genetic elements providing copper...
Bacteria use diverse strategies and molecular machinery to maintain copper homeostasis and to cope with its toxic effects. Some genetic elements providing copper resistance are acquired by horizontal gene transfer; however, little is known about how they are controlled and integrated into the central regulatory network. Here, we studied two copper-responsive systems in a clinical isolate of Pseudomonas paraeruginosa and deciphered the regulatory and cross-regulation mechanisms. To do so, we combined mutagenesis, transcriptional fusion analyses and copper sensitivity phenotypes. Our results showed that the accessory CusRS two-component system (TCS) responds to copper and activates both its own expression and that of the adjacent nine-gene operon (the pcoA2 operon) to provide resistance to elevated levels of extracellular copper. The same locus was also found to be regulated by two core-genome-encoded TCSs-the copper-responsive CopRS and the zinc-responsive CzcRS. Although the target palindromic sequence-ATTCATnnATGTAAT-is the same for the three response regulators, transcriptional outcomes differ. Thus, depending on the operon/regulator pair, binding can result in different activation levels (from none to high), with the systems demonstrating considerable plasticity. Unexpectedly, although the classical CusRS and the noncanonical CopRS TCSs rely on distinct signaling mechanisms (kinase-based vs. phosphatase-based), we discovered cross-talk in the absence of the cognate sensory kinases. This cross-talk occurred between the proteins of these two otherwise independent systems. The cusRS-pcoA2 locus is part of an Integrative and Conjugative Element and was found in other Pseudomonas strains where its expression could provide copper resistance under appropriate conditions. The results presented here illustrate how acquired genetic elements can become part of endogenous regulatory networks, providing a physiological advantage. They also highlight the potential for broader effects of accessory regulatory proteins through interference with core regulatory proteins.
Topics: Copper; Pseudomonas; Gene Expression Regulation, Bacterial; Operon; Bacterial Proteins; Drug Resistance, Bacterial; Signal Transduction
PubMed: 38861577
DOI: 10.1371/journal.pgen.1011325 -
Applied Microbiology and Biotechnology Jun 2024Ethylene glycol (EG) is an industrially important two-carbon diol used as a solvent, antifreeze agent, and building block of polymers such as poly(ethylene... (Review)
Review
Ethylene glycol (EG) is an industrially important two-carbon diol used as a solvent, antifreeze agent, and building block of polymers such as poly(ethylene terephthalate) (PET). Recently, the use of EG as a starting material for the production of bio-fuels or bio-chemicals is gaining attention as a sustainable process since EG can be derived from materials not competing with human food stocks including CO, syngas, lignocellulolytic biomass, and PET waste. In order to design and construct microbial process for the conversion of EG to value-added chemicals, microbes capable of catabolizing EG such as Escherichia coli, Pseudomonas putida, Rhodococcus jostii, Ideonella sakaiensis, Paracoccus denitrificans, and Acetobacterium woodii are candidates of chassis for the construction of synthetic pathways. In this mini-review, we describe EG catabolic pathways and catabolic enzymes in these microbes, and further review recent advances in microbial conversion of EG to value-added chemicals by means of metabolic engineering. KEY POINTS: • Ethylene glycol is a potential next-generation feedstock for sustainable industry. • Microbial conversion of ethylene glycol to value-added chemicals is gaining attention. • Ethylene glycol-utilizing microbes are useful as chassis for synthetic pathways.
Topics: Ethylene Glycol; Metabolic Engineering; Metabolic Networks and Pathways; Bacteria; Pseudomonas putida; Biofuels; Escherichia coli
PubMed: 38861200
DOI: 10.1007/s00253-024-13179-2 -
Annals of Clinical Microbiology and... Jun 2024Detection of carbapenem-resistant Pseudomonas aeruginosa (CR-PA) in humans is important to prevent transmission. However, the most optimal culture method to detect CR-PA... (Review)
Review
BACKGROUND
Detection of carbapenem-resistant Pseudomonas aeruginosa (CR-PA) in humans is important to prevent transmission. However, the most optimal culture method to detect CR-PA is unknown. This systematic review aims to determine which culture method is most sensitive and which culture methods are used to detect CR-PA in humans. Second, to establish the most feasible culture method taking into account the turnaround time (TAT), and third, to provide an overview of the sampling sites used to detect carriage.
METHODS
We systematically searched the electronic databases Embase, Medline Ovid, Cochrane, Scopus, CINAHL, and Web of Science until January 27, 2023. All diagnostic accuracy studies comparing two or more culture methods to detect CR-PA and recent outbreak or surveillance reports on CR-PA carriage or infection in humans, which describe culture methods and their results, were eligible for inclusion. We used QUADAS-2 guideline for diagnostic accuracy studies and the STROBE or ORION guideline for outbreak-surveillance studies to assess the risk of bias.
RESULTS
Six diagnostic accuracy studies were included. An enrichment broth was found to increase the detection of CR-PA. Using an enrichment broth extended the TAT by 18-24 h, yet selective media could reduce the TAT by 24 h compared to routine media. In total, 124 outbreak-surveillance studies were included, of which 17 studies with surveillance samples and 116 studies with clinical samples. In outbreak-surveillance studies with surveillance samples, perianal, rectal swabs or stools were the most common sampling site/specimen (13/17, 76%). A large variety was observed in whether and which kind of enrichment broth and selective media were used.
CONCLUSIONS
We found a benefit of using an enrichment step prior to inoculation of the material onto selective media for the detection of CR-PA. More research is needed to determine the most sensitive sampling site and culture method.
TRAIL REGISTRATION
This study was registered in the PROSPERO International prospective register of systematic reviews (registration number: CRD42020207390, http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42020207390 ).
Topics: Humans; Pseudomonas aeruginosa; Carbapenems; Pseudomonas Infections; Anti-Bacterial Agents; Carrier State; Microbial Sensitivity Tests; Culture Media
PubMed: 38858708
DOI: 10.1186/s12941-024-00707-1 -
BMC Microbiology Jun 2024Quorum sensing (QS) is a cell density-based intercellular communication system that controls virulence gene expression and biofilm formation. In Pseudomonas aeruginosa...
BACKGROUND
Quorum sensing (QS) is a cell density-based intercellular communication system that controls virulence gene expression and biofilm formation. In Pseudomonas aeruginosa (P. aeruginosa), the LasR system sits at the top of the QS hierarchy and coordinates the expression of a series of important traits. However, the role of lasR in phage infection remains unclear. This study aims to investigate the role of lasR QS in phage infection.
METHODS
The P. aeruginosa phage was isolated from sewage, and its biological characteristics and whole genome were analyzed. The adsorption receptor was identified via a phage adsorption assay. Following lasR gene knockout, the adsorption rate and bactericidal activity of phage were analyzed. Finally, real-time quantitative polymerase chain reaction (RT-qPCR) was conducted to explore how lasR promoting phage infection.
RESULTS
The lytic phage vB_Pae_PLY was isolated and lipopolysaccharide (LPS) was identified as its adsorption receptor. The adsorption rate and bactericidal activity of vB_Pae_PLY were reduced after lasR knockout. RT-qPCR results showed that the expression of galU, a key gene involved in LPS synthesis, was down-regulated, and several genes related to type IV pili (T4P) were also down-regulated in the lasR mutant PaΔlasR.
CONCLUSIONS
The study showed that QS lasR may promote phage vB_Pae_PLY infection by involving in the synthesis of LPS and T4P. This study provides an example of QS in promoting phage infection and deepens the understanding of phage-bacteria interactions.
Topics: Pseudomonas aeruginosa; Quorum Sensing; Trans-Activators; Bacterial Proteins; Pseudomonas Phages; Sewage; Gene Expression Regulation, Bacterial; Lipopolysaccharides; Gene Knockout Techniques
PubMed: 38858621
DOI: 10.1186/s12866-024-03349-7 -
Scientific Reports Jun 2024Lignin, a heterogeneous aromatic polymer present in plant biomass, is intertwined with cellulose and hemicellulose fibrils, posing challenges to its effective...
Lignin, a heterogeneous aromatic polymer present in plant biomass, is intertwined with cellulose and hemicellulose fibrils, posing challenges to its effective utilization due to its phenolic nature and recalcitrance to degradation. In this study, three lignin utilizing bacteria, Klebsiella sp. LEA1, Pseudomonas sp. LEA2, and Burkholderia sp. LEA3, were isolated from deciduous forest soil samples in Nan province, Thailand. These isolates were capable of growing on alkali lignin and various lignin-associated monomers at 40 °C under microaerobic conditions. The presence of Cu significantly enhanced guaiacol oxidation in Klebsiella sp. LEA1 and Pseudomonas sp. LEA2. Lignin-related monomers and intermediates such as 2,6-dimethoxyphenol, 4-vinyl guaiacol, 4-hydroxybenzoic acid, benzoic acid, catechol, and succinic acid were detected mostly during the late stage of incubation of Klebsiella sp. LEA1 and Pseudomonas sp. LEA2 in lignin minimal salt media via GC-MS analysis. The intermediates identified from Klebsiella sp. LEA1 degradation suggested that conversion and utilization occurred through the β-ketoadipate (ortho-cleavage) pathway under limited oxygen conditions. The ability of these bacteria to thrive on alkaline lignin and produce various lignin-related intermediates under limited oxygen conditions suggests their potential utility in oxygen-limited processes and the production of renewable chemicals from plant biomass.
Topics: Lignin; Soil Microbiology; Pseudomonas; Forests; Oxygen; Klebsiella; Burkholderia; Biodegradation, Environmental
PubMed: 38858437
DOI: 10.1038/s41598-024-64237-8