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Biomolecules Jun 2024Leucine residues are commonly found in the hydrophobic face of antimicrobial peptides (AMPs) and are crucial for membrane permeabilization, leading to the cell death of...
Leucine residues are commonly found in the hydrophobic face of antimicrobial peptides (AMPs) and are crucial for membrane permeabilization, leading to the cell death of invading pathogens. Melittin, which contains four leucine residues, demonstrates broad-spectrum antimicrobial properties but also significant cytotoxicity against mammalian cells. To enhance the cell selectivity of melittin, this study synthesized five analogs by replacing leucine with its structural isomer, 6-aminohexanoic acid. Among these analogs, Mel-LX3 exhibited potent antibacterial activity against both Gram-positive and Gram-negative bacteria. Importantly, Mel-LX3 displayed significantly reduced hemolytic and cytotoxic effects compared to melittin. Mechanistic studies, including membrane depolarization, SYTOX green uptake, FACScan analysis, and inner/outer membrane permeation assays, demonstrated that Mel-LX3 effectively permeabilized bacterial membranes similar to melittin. Notably, Mel-LX3 showed robust antibacterial activity against methicillin-resistant (MRSA) and multidrug-resistant (MDRPA). Furthermore, Mel-LX3 effectively inhibited biofilm formation and eradicated existing biofilms of MDRPA. With its improved selective antimicrobial and antibiofilm activities, Mel-LX3 emerges as a promising candidate for the development of novel antimicrobial agents. We propose that the substitution of leucine with 6-aminohexanoic acid in AMPs represents a significant strategy for combating resistant bacteria.
Topics: Melitten; Biofilms; Pseudomonas aeruginosa; Microbial Sensitivity Tests; Anti-Bacterial Agents; Methicillin-Resistant Staphylococcus aureus; Humans; Hemolysis; Aminocaproic Acid; Gram-Negative Bacteria; Animals
PubMed: 38927102
DOI: 10.3390/biom14060699 -
BMC Microbiology Jun 2024The incidence of hospital-acquired infections in extensively drug-resistant Pseudomonas aeruginosa (XDR-PA) has been increasing worldwide and is frequently associated...
BACKGROUND
The incidence of hospital-acquired infections in extensively drug-resistant Pseudomonas aeruginosa (XDR-PA) has been increasing worldwide and is frequently associated with an increase in mortality and morbidity rates. The aim of this study was to characterize clinical XDR-PA isolates recovered during six months at three different hospitals in Egypt.
RESULTS
Seventy hospital-acquired clinical isolates of P. aeruginosa were classified into multidrug-resistant (MDR), extensively drug-resistant (XDR) and pandrug-resistant (PDR), according to their antimicrobial resistance profile. In addition, the possession of genes associated with mobile genetic elements and genes encoding antimicrobial resistance determinants among isolates were detected using polymerase chain reaction. As a result, a significant percentage of the isolates (75.7%) were XDR, while 18.5% were MDR, however only 5.7% of the isolates were non-MDR. The phenotypic detection of carbapenemases, extended-spectrum β-lactamases (ESBLs) and metallo β-lactamase (MBL) enzymes showed that 73.6% of XDR-PA isolates were carbapenemases producers, whereas 75.5% and 88.7% of XDR-PA isolates produced ESBLs and MBL respectively. In addition, PCR screening showed that oxa gene was the most frequently detected gene of carbapenemases (91.4%), while aac(6')-lb gene was mostly detected (84.3%) among the screened aminoglycosides-resistance genes. Furthermore, the molecular detection of the colistin resistance gene showed that 12.9% of isolates harbored mcr-1 gene. Concerning mobile genetic element markers (intI, traA, tnp513, and merA), intI was the highest detected gene as it was amplified in 67 isolates (95.7%). Finally, phylogenetic and molecular typing of the isolates via ERIC-PCR analysis revealed 10 different ERIC fingerprints.
CONCLUSION
The present study revealed a high prevalence of XDR-PA in hospital settings which were resistant to a variety of antibiotics due to several mechanisms. In addition, 98% of the XDR-PA clinical isolates contained at least one gene associated with movable genetic elements, which could have aided the evolution of these XDR-PA strains. To reduce spread of drug resistance, judicious use of antimicrobial agents and strict infection control measures are therefore essential.
Topics: Pseudomonas aeruginosa; Humans; Pseudomonas Infections; Drug Resistance, Multiple, Bacterial; Cross Infection; Egypt; beta-Lactamases; Anti-Bacterial Agents; Microbial Sensitivity Tests; Bacterial Proteins; Hospitals; Interspersed Repetitive Sequences; Polymerase Chain Reaction
PubMed: 38926687
DOI: 10.1186/s12866-024-03321-5 -
Microbial Biotechnology Jun 2024Pyruvate dehydrogenase (PDH) catalyses the irreversible decarboxylation of pyruvate to acetyl-CoA, which feeds the tricarboxylic acid cycle. We investigated how the loss...
Inactivation of Pseudomonas putida KT2440 pyruvate dehydrogenase relieves catabolite repression and improves the usefulness of this strain for degrading aromatic compounds.
Pyruvate dehydrogenase (PDH) catalyses the irreversible decarboxylation of pyruvate to acetyl-CoA, which feeds the tricarboxylic acid cycle. We investigated how the loss of PDH affects metabolism in Pseudomonas putida. PDH inactivation resulted in a strain unable to utilize compounds whose assimilation converges at pyruvate, including sugars and several amino acids, whereas compounds that generate acetyl-CoA supported growth. PDH inactivation also resulted in the loss of carbon catabolite repression (CCR), which inhibits the assimilation of non-preferred compounds in the presence of other preferred compounds. Pseudomonas putida can degrade many aromatic compounds, most of which produce acetyl-CoA, making it useful for biotransformation and bioremediation. However, the genes involved in these metabolic pathways are often inhibited by CCR when glucose or amino acids are also present. Our results demonstrate that the PDH-null strain can efficiently degrade aromatic compounds even in the presence of other preferred substrates, which the wild-type strain does inefficiently, or not at all. As the loss of PDH limits the assimilation of many sugars and amino acids and relieves the CCR, the PDH-null strain could be useful in biotransformation or bioremediation processes that require growth with mixtures of preferred substrates and aromatic compounds.
Topics: Pseudomonas putida; Catabolite Repression; Pyruvate Dehydrogenase Complex; Hydrocarbons, Aromatic; Biodegradation, Environmental; Acetyl Coenzyme A; Pyruvic Acid; Gene Deletion; Metabolic Networks and Pathways
PubMed: 38923400
DOI: 10.1111/1751-7915.14514 -
Anais Da Academia Brasileira de Ciencias 2024I. paraguariensis St. Hil. is a south American species of agronomic interest with studies supporting its medicinal properties. As the investigation of active ingredients...
I. paraguariensis St. Hil. is a south American species of agronomic interest with studies supporting its medicinal properties. As the investigation of active ingredients with antimicrobial effect from medicinal plants is a suitable approach to the current antibacterial resistance problem, the aim of the present study was to determine the antibacterial activity of yerba mate ethanolic extracts against carbapenemase-producing gram-negative bacteria (reference strains and clinical isolates). Extracts showed antibacterial activity against Klebsiella pneumoniae ATCC® BAA-2342™ (KPC producing), Providencia rettgeri (NDM producing), Pseudomonas aeruginosa (MBL producing) and P. aeruginosa (VIM producing) at the concentrations tested. The Minimal-Inhibitory-Concentration and Minimal-Bactericidal-Concentration values ranged between 1 and 32 mg.ml-1 for the reference strains, and between 0.125 and 1 mg.ml-1 for the clinical isolates. The MBC/MIC index characterized the extracts as bactericidal. The combinations of commercial antibiotics and extracts showed a synergistic action on the reference strains studied. The lethal concentration 50 obtained using the Artemia salina toxicity assay were higher than 1 mg.ml-1 for all the extracts, indicating a low toxicity. The in vitro activity and low toxicity suggest that ethanolic I. paraguariensis leaf extracts constitute an outstanding source for new antibacterial compounds, and further studies should be carried out to understand their mechanism of action.
Topics: Plant Extracts; Ilex paraguariensis; beta-Lactamases; Microbial Sensitivity Tests; Plant Leaves; Anti-Bacterial Agents; Gram-Negative Bacteria; Bacterial Proteins; Pseudomonas aeruginosa; Animals; Klebsiella pneumoniae
PubMed: 38922267
DOI: 10.1590/0001-3765202420221129 -
Toxins Jun 2024Extensively drug-resistant infections are emerging as a significant threat associated with adverse patient outcomes. Due to this organism's inherent properties of...
Extensively drug-resistant infections are emerging as a significant threat associated with adverse patient outcomes. Due to this organism's inherent properties of developing antibiotic resistance, we sought to investigate alternative strategies such as identifying "high value" antigens for immunotherapy-based purposes. Through extensive database mining, we discovered that numerous Gram-negative bacterial (GNB) genomes, many of which are known multidrug-resistant (MDR) pathogens, including , horizontally acquired the evolutionarily conserved gene encoding Zonula occludens toxin (Zot) with a substantial degree of homology. The toxin's genomic footprint among so many different GNB stresses its evolutionary importance. By employing in silico techniques such as proteomic-based phylogenetic tracing, in conjunction with comparative structural modeling, we discovered a highly conserved intermembrane associated stretch of 70 amino acids shared among all the GNB strains analyzed. The characterization of our newly identified antigen reveals it to be a "high value" vaccine candidate specific for . This newly identified antigen harbors multiple non-overlapping B- and T-cell epitopes exhibiting very high binding affinities and can adopt identical tertiary structures among the least genetically homologous strains. Taken together, using proteomic-driven reverse vaccinology techniques, we identified multiple "high value" vaccine candidates capable of eliciting a polarized immune response against all the genetic variants tested.
Topics: Pseudomonas aeruginosa; Phylogeny; Pseudomonas Infections; Humans; Epitopes, T-Lymphocyte; Pseudomonas Vaccines; Epitopes, B-Lymphocyte
PubMed: 38922165
DOI: 10.3390/toxins16060271 -
NPJ Biofilms and Microbiomes Jun 2024It is becoming increasingly apparent that commensal skin bacteria have an important role in wound healing and infection progression. However, the precise mechanisms...
It is becoming increasingly apparent that commensal skin bacteria have an important role in wound healing and infection progression. However, the precise mechanisms underpinning many of these probiotic interactions remain to be fully uncovered. In this work, we demonstrate that the common skin commensal Cutibacterium acnes can limit the pathogenicity of the prevalent wound pathogen Pseudomonas aeruginosa in vivo. We show that this impact on pathogenicity is independent of any effect on growth, but occurs through a significant downregulation of the Type Three Secretion System (T3SS), the primary toxin secretion system utilised by P. aeruginosa in eukaryotic infection. We also show a downregulation in glucose acquisition systems, a known regulator of the T3SS, suggesting that glucose availability in a wound can influence infection progression. C. acnes is well known as a glucose fermenting organism, and we demonstrate that topically supplementing a wound with glucose reverses the probiotic effects of C. acnes. This suggests that introducing carbon source competition within the wound microenvironment may be an effective way to prevent or limit wound infection.
Topics: Pseudomonas aeruginosa; Glucose; Animals; Type III Secretion Systems; Propionibacterium acnes; Wound Infection; Mice; Pseudomonas Infections; Skin; Carbon; Wound Healing; Antibiosis; Disease Progression; Humans
PubMed: 38918415
DOI: 10.1038/s41522-024-00518-4 -
Microbiology Resource Announcements Jun 2024We report the draft genome sequence of three marine bacteria belonging to and genera, with hydrocarbonoclastic metabolism for oil and monoaromatic hydrocarbon...
We report the draft genome sequence of three marine bacteria belonging to and genera, with hydrocarbonoclastic metabolism for oil and monoaromatic hydrocarbon degradation. The genomic information of these organisms contributes to the knowledge of natural and polluted marine environments with ubiquitous presence of hydrocarbons as a selective pressure.
PubMed: 38916305
DOI: 10.1128/mra.00335-24 -
Frontiers in Immunology 2024Fish intestinal health under intensive aquaculture mode plays an important role in growth, development, and immune function. The present study was aimed to... (Comparative Study)
Comparative Study
Fish intestinal health under intensive aquaculture mode plays an important role in growth, development, and immune function. The present study was aimed to systematically investigate the differences of intestinal health between wild and cultured by biochemical parameters, histomorphology, and molecular biology. A total of 15 healthy per group, with an average body weight of 45 g, were sampled to analyze intestinal health parameters. Compared with wild fish, the cultured in the foregut had lower trypsin, lipase, SOD, CAT, T-AOC, and GSH-Px activities ( < 0.05) and higher amylase activity and MDA content ( < 0.05). The villus circumference and goblet cells in the cultured group were significantly lower than those in the wild group ( < 0.05). In addition, the cultured fish showed lower relative expression levels of , , , , , , , , , , , , and ( < 0.05) and higher , , , , and mRNA expressions than those of wild fish ( < 0.05). In terms of gut microbiota, the cultured group at the phylum level displayed higher percentages of and and lower percentages of , , , , and compared to the wild group ( < 0.05). At the genus level, higher abundances of and and lower abundances of and were observed in the cultured group than in the wild group ( < 0.05). To our knowledge, this is the first investigation of the intestinal health status between wild and cultured in terms of biochemistry, histology, and molecular biology levels. Overall, the present study showed significant differences in intestinal health between wild and cultured and the main manifestations that wild had higher intestinal digestion, antioxidant capacity, and intestinal barrier functions than cultured These results would provide theoretical basis for the subsequent upgrading of healthy aquaculture technology and nutrient regulation of intestinal health of cultured
Topics: Animals; Aquaculture; Intestines; Gastrointestinal Microbiome; Smegmamorpha; Intestinal Mucosa; Cytokines; Animals, Wild
PubMed: 38915412
DOI: 10.3389/fimmu.2024.1411544 -
Scientific Reports Jun 2024Aloe barbadensis is a drought-tolerant perennial medicinal plant with both nutritional and cosmetic uses. Drought is one of the main abiotic stresses limiting plant...
Evaluation of the benefits of plant growth-promoting rhizobacteria and mycorrhizal fungi on biochemical and morphophysiological traits of Aloe barbadensis Mill under water deficit stress.
Aloe barbadensis is a drought-tolerant perennial medicinal plant with both nutritional and cosmetic uses. Drought is one of the main abiotic stresses limiting plant growth and development. However, the use of drought-resistant plants combined with beneficial soil micro-organisms could improve the effectiveness of biological methods to mitigate drought damage. This research aims to evaluate the effects of Funneliformis mosseae (MF), plant growth-promoting rhizobacteria (PGPR) (including Pseudomonas putida and Pantoea agglomerans), and their co-inoculation on the macronutrient status, antioxidant enzyme activities, and other morphophysiological traits of A. barbadensis under four irrigation regimes [25%, 50%, 75% and 100% of water requirement (WR)]. Three harvests were conducted, revealing that inoculation enhanced the survival rate and shoot fresh weight (SFW) compared to the control plants. However, at 25% WR, the SFW was reduced by 43% more than the control. across all harvests, while the PGPR + MF treatment showed increases of more than 19%, 11%, and 17% compared to the control, MF, and PGPR treatments, respectively. The results also showed that A. barbadensis exhibited innate drought tolerance up to a 50% WR level by enhancing physiological defenses, such as antioxidant enzyme activity. Inoculation increased the macronutrient status of the plant at all levels of irrigation regimes especially under severe drought conditions. The highest levels of nitrogen (N) (16.24 mg g DW) and phosphorus (P) (11.29 mg g DW) were observed in the PGPR + MF treatment at 100% WR. The maximum relative water content under MF inoculation and 75% WR (98.24%) (98.24%) was reached. PGPR + MF treatment alleviated drought-induced osmotic stress, as indicated by reduced antioxidant enzyme activities and electrolyte leakage. However, P. putida and P. agglomerans strains alone or in combination with F. mosseae increased plant yield, macronutrient uptake and antioxidant enzyme activity. This study underscores the potential of these PGPR and MF strains as invaluable biological tools for the cultivation of A. barbadensis in regions with severe drought stress.
Topics: Aloe; Mycorrhizae; Droughts; Pseudomonas putida; Antioxidants; Plant Roots; Water; Stress, Physiological; Soil Microbiology; Pantoea; Dehydration; Fungi
PubMed: 38914637
DOI: 10.1038/s41598-024-64878-9 -
PloS One 2024Exploration of interspecies interactions between microorganisms can have taxonomic, ecological, evolutionary, or medical applications. To better explore interactions...
Exploration of interspecies interactions between microorganisms can have taxonomic, ecological, evolutionary, or medical applications. To better explore interactions between microorganisms it is important to establish the ideal conditions that ensure survival of all species involved. In this study, we sought to identify the ideal biotic and abiotic factors that would result in high co-culture viability of two interkingdom species, Pseudomonas aeruginosa and Acanthamoeba castellanii, two soil dwelling microbes. There have been limited studies showing long-term interactions between these two organisms as co-culture can result in high mortality for one or both organisms suggesting a predator-predator interaction may exist between them. In this study, we identified biotic and abiotic conditions that resulted in a high viability for both organisms in long-term co-culture, including optimizing temperature, nutrient concentration, choice of bacterial strains, and the initial ratio of interacting partners. These two species represent ideal partners for studying microbial interactions because amoebae act similarly to mammalian immune cells in many respects, and this can allow researchers to study host-pathogen interactions in vitro. Therefore, long-term interaction studies between these microbes might reveal the evolutionary steps that occur in bacteria when subjected to intense predation, like what occurs when pathogens enter the human body. The culture conditions characterized here resulted in high viability for both organisms for at least 14-days in co-culture suggesting that long-term experimental studies between these species can be achieved using these culture conditions.
Topics: Acanthamoeba castellanii; Pseudomonas aeruginosa; Coculture Techniques; Microbial Interactions; Temperature; Soil Microbiology
PubMed: 38913685
DOI: 10.1371/journal.pone.0305973