Silver nanoparticles synthesized from Pseudomonas aeruginosa pyoverdine: Antibiofilm and antivirulence agents

Green synthesis of silver nanoparticles for functional cotton fabrics: antimicrobial efficacy against multidrug-resistant bacteria and cytotoxicity evaluation

Bacterial infections associated with healthcare are a challenge on a global scale due to the high morbidity and mortality rates, especially those caused by multidrug-resistant isolates. Hospital textiles are abiotic surfaces that may serve as a means of disseminating and persisting microorganisms in hospitals, as microorganisms can remain viable on these surfaces for up to months. In this study, we employed a green synthesis approach utilizing guava leaf extract (Psidium guajava) to produce silver nanoparticles, which were then incorporated into a cotton fabric. Antimicrobial properties and the cytotoxicity of the functional textile were assessed. The finding indicated that the green synthesis method was efficient and resulted in a predominant population of nanoparticles with diameters ranging from 25 to 84 nm that were uniformly dispersed in the textile. The functional textile exhibited low toxicity and high antimicrobial efficiency, even against multidrug-resistant microorganisms of particular concern in hospital settings. Atomic force microscopy carried out evidenced invaginations in the cell wall of bacteria submitted to this textile, suggesting surface damage as an important mechanism of action silver nanoparticles incorporated.

Bacteriocin isolated from Ralstonia mannitolilytica and bacteriocin-capped silver nanoparticles: Comparative effects on biofilm formation and LuxS Gene's expressions by Proteus mirabilis as an approach to counter MDR catheter infection

Among undesirables in treating certain infections and diseases is the contamination of catheters, especially of the microbes' resistance to drugs. The situation has necessitated the search for alternative antimicrobial agents. Bacteriocin category, antibiotic-originate, peptide-natured, Ralstonia mannitolilytica microbes-produced, bacteriocin material, and the semi-pure bacteriocin capped silver metal nanoparticles (AgNPs) were used for combating the MDR (multi drug resistance) organism, Proteus mirabilis, which is the third-most common cause of UTI (urinary tract infection), and that is linked to catheter use, are being recommended for clinical use with certain development. The crude microbial product was isolated from the microbial entity, Ralstonia mannitolilytica, which grows in crude petroleum-contaminated soil, and was semi-purified for use in the synthesis of the bacteriocin-capped AgNPs. The prepared nanoparticles were characterized using X-ray diffraction, indicating the silver element's presence; field emission scanning electron microscopy, revealing near-spherical but irregular shapes of the bacteriocin-capped AgNPs with a size range of 34-46 nm; and atomic force microscopic analysis, which demonstrated the nanoparticles surface characteristics. The DLS analysis established the negative charge, and an average hydrodynamic size of 51 nm, while the UV-Vis spectroscopic analysis showed the absorption maxima (λmax) at 454 nm. The P. mirabilis isolates were numbered according to MDR detection by the VITEK 2 system (A to J), and the microbes appeared as a pale-coloured colony on MacConkey agar. The biofilm formation screening revealed the highest biofilm-producing isolates, identified as A, B, C, and D. The treatments with both bacteriocin and the bacteriocin-capped AgNPs showed that bacteriocin inhibited the biofilm formation for isolates A, B, and C, but isolate D was less affected, while bacteriocin capped AgNPs inhibited the film formation in isolates A, C, and D more than the bacteriocin alone. However, the activity level was low to moderate. In addition, the LuxS gene-down-regulating effects of bacteriocin and bacteriocin-capped AgNPs were also observed. The expression of the LuxS gene in P. mirabilis was lowered by bacteriocin-capped AgNPs during biofilm formation, while the isolates B and C lowered their expressions of the LuxS gene more effectively when the bacteriocin was used. The study finds the use of bacteriocin and bacteriocin-capped AgNPs of value for developing these products, especially bacteriocin-capped AgNPs, for managing the catheter infections. The products need further development and clinical testings.

Enhanced bioavailability and improved antimicrobial, antibiofilm, and antivirulence activities of fish gelatin-based nanoformulations prepared by coating of maltol-gold nanoparticles

Biofilm formation by a single and multiple microbial species poses a significant challenge to healthcare due to biofilm-related antibiotic resistance. This study aimed to develop a nanoformulation (Mal-AuNP-Gel) by synthesizing gold nanoparticles (AuNPs) with maltol (Mal), and coating them with fish gelatin (Gel) to reduce biofilm formation and virulence characteristics of microbial pathogens. Mal-AuNP-Gel showed increased antibacterial activity against all pathogens studied, including bacterial (Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Listeria monocytogenes, Escherichia coli, and methicillin-resistant S. aureus) and fungal pathogens (e.g., Candida albicans), with MICs up to 2-fold lower than those of Mal-AuNPs. At the sub-MIC level, Mal-AuNPs-Gel, compared to Mal-AuNPs, improved the inhibition of initial-stage biofilm development by a single species of P. aeruginosa, S. aureus, and C. albicans as well as the mixed-species biofilm of S. aureus and C. albicans. Additionally, these nanoparticles significantly inhibited several virulence characteristics such as hemolysis, pyoverdine and pyocyanin production, protease activity, and motility of P. aeruginosa. Furthermore, the expression of genes associated with biofilm formation, quorum sensing, motility, and virulence factors in P. aeruginosa was found to be suppressed by Mal-AuNPs-Gel at a higher level than that of Mal-AuNPs, corroborating the phenotypic effects. The non-cytotoxic effects of Mal-AuNPs and Mal-AuNPs-Gel at sub-MIC levels, as evidenced by results of in vitro cell cytotoxicity and in vivo phytotoxicity tests, further indicated biocompatibility of the synthesized nanoparticles.

Endophytic fungi-bioinspired nanoparticles potential to control infectious disease

The growing demand for nanomedicine and its potentially diverse biological function required the investigation of raw materials for fabricating the nanomaterial. Current developments have emphasized the implementation of green chemistry to develop metal-oxide and metal nanoparticles. Endophytic fungi have emerged as a potential reservoir of bioactive compounds exemplified by unique structures and influential antibacterial properties. Over the past decade, substantial progress has been achieved in uncovering and profiling these valuable antibacterial compounds. These endophytic fungi-derived bioactive chemicals have diverse applications in various biological properties. Nanoparticle synthesis from materials derived from endophytic fungi, be it whole extracts or pure components, owing to their accessibility, cost-effectiveness in fabrication, material-tissue compatibility, and modest cytotoxicity toward higher organism cells. Nanoparticles from endophytic fungi have been utilized to treat various diseases, including those caused by bacterial, viral, and fungal pathogens. The present review provides a comprehensive discussion of the mechanistic insight into the synthesis and application of endophytic fungi-bioinspired nanoparticles as potential therapeutic agents to control microbial infection. The underlying action mechanism involved in the antimicrobial action of the nanoparticles has also been discussed. The discussion highlights various attributes of nanoparticles that may significantly benefit future researchers as potential therapeutic agents to control microbial infection.

Green Biosynthesis of Bimetallic Copper Oxide-Selenium Nanoparticles Using Leaf Extract of Lagenaria Siceraria: Antibacterial, Anti-Virulence Activities Against Multidrug-Resistant Pseudomonas Aeruginosa

Introduction

Clinical isolates of Pseudomonas aeruginosa (P. aeruginosa) are among the most recovered bacteria with phenotypic antimicrobial resistance. Bimetallic nanoparticles (BNPs) have received much attention for antimicrobial activity in the last decade. This research aimed to biosynthesize bimetallic copper oxide-selenium nanoparticles (CuO-Se BNPs) and to assess its bioactivity on various P. aeruginosa clinical isolates.

Methodology

Based on the possible synergistic effects, CuO-Se BNPs were selected and biosynthesized using leaf extract of Lagenaria siceraria (L. siceraria) for the first time. The obtained BNPs were characterized using UV-vis spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and transmission and scanning electron microscopes. The capability of Cu-Se BNPs to cease the growth of P. aeruginosa isolates and to reduce their virulence characters was evaluated. Also, different cell lines were used to assess its cytotoxicity and anticancer activity.

Results

The elemental composition of CuO and Se was revealed by the UV, XRD, and EDX data, indicating the synthesis of CuO-Se core shell BNPs with a size of 50 nm. In well diffusion assay, CuO-Se BNPs P. aeruginosa growth with 10-21 mm inhibition zone diameter and 38-95% inhibition. Also, the minimum inhibitory concentration and minimum bactericidal concentration were in a relatively wide range of 7.8-250 μg/mL and 31.2-500 μg/mL, respectively, with tolerance level range of 2-16. Additionally, CuO-Se BNPs shown anti-pyocyanin activity of 4.35-63.21% inhibition while the anti-proteolytic activity was in a range of 4.96-12.59% and anti-pyoverdine effect was in a range of 0.24-83.41%. The IC50 against Wi-38 normal cells was 267.2 µg/mL while the IC50 were 31.1 and 83.4 µg/mL against MCF-7 and Hep-G2, respectively, indicating promising anticancer activity.

Conclusion

This research demonstrates the promising antibacterial, anti-virulence, and antitumor properties with safe low concentrations of CuO-Se NPs, synthesized via an eco-friendly green synthesis method without the use of toxic chemicals, offering a sustainable and cost-effective alternative.

Synergistic Activity of Gloeophyllum striatum-Derived AgNPs with Ciprofloxacin and Gentamicin Against Human Pathogenic Bacteria

Silver nanoparticles (AgNPs) are used in a variety of different fields due to their excellent antimicrobial potential. Despite clear advantages, concerns about their toxicity have arisen, also concerning biogenic nanoparticles. Simultaneously, global healthcare is facing a problem of spreading antimicrobial resistance towards existing antibiotics. Using combined therapies involving AgNPs and antibiotics seems to be a promising solution to the above problems. The aim of this study was to evaluate the enhancement of the effectiveness of AgNPs, ciprofloxacin, and gentamicin against Staphylococcus aureus and Pseudomonas aeruginosa. The research involved the assessment of antimicrobial and antibiofilm-forming activities and the analysis of phospholipid and fatty acid profiles. Our results showed that combining the tested antimicrobials can enhance their activity against the tested bacterial strains. However, no effect was observed while mixing AgNPs with ciprofloxacin against P. aeruginosa. The most significant effect was obtained by combining 3.125 µg/mL of AgNPs with 0.125 µg/mL of gentamicin against S. aureus. It was also shown that the tested antimicrobials applied in combination exhibited an increased inhibitory activity towards bacterial biofilm formation by S. aureus. Lipidomic analysis revealed that under the influence of the tested antimicrobials, the properties of the cell membrane were altered in different ways depending on the bacterial strain.

Biosynthesized silver nanoparticles at subinhibitory concentrations as inhibitors of quorum sensing, pathogenicity, and biofilm formation in Pseudomonas aeruginosa PAO1

Pseudomonas aeruginosa infections associated with biofilm are a significant clinical challenge due to the limited efficacy of traditional antibiotics or combination therapies. Hence, exploring novel strategies and assessing different compounds for their anti-biofilm or anti-quorum sensing (QS) properties is imperative. One of the various applications of silver nanoparticles (AgNPs) is to use them as an antimicrobial agent to target bacteria resistant to common antibiotics. This study evaluates the anti-biofilm and anti-virulence effect of biosynthesized AgNPs against P. aeruginosa PAO1 at subinhibitory concentration levels. Minimum inhibitory concentrations (MICs) and biofilm formation capacity were evaluated by the microdilution method and crystal violet method, respectively. Motility assay and virulence factors were investigated in the presence of AgNPs. It was observed that green-synthesized AgNPs at sub-MIC (50 μg/mL) suppressed P. aeruginosa biofilm formation by 78 %. Increased dose-dependent inhibitory effects on virulence phenotypes (LasB elastase, LasA protease, pyocyanin, and motility) regulated by QS were observed. In addition, the relative expression levels of biofilm-related genes including algC, pslA, and pelA were analyzed using RT-qPCR. The expression level of QS-regulated biofilm genes after AgNPs treatment sub-MIC led to a decrease in the expression of algC, pslA, and pelA by 77 %, 83 %, and 68 %, respectively. The findings of this study demonstrated how green AgNPs can effectively inhibit QS at sub-MIC concentrations, indicating their potential as antivirulence agents to deal with challenges related to biofilm formation and antimicrobial resistance in P. aeruginosa. This presents a promising alternative to traditional antibiotics in antimicrobial therapy.

Unlocking the Synergistic Potential and Efficacy of Biosurfactant-Silver Nanoparticle for Enhanced Antimicrobial Activities

Microorganisms can produce various amphiphilic compounds known as biosurfactants, with diverse applications in distinct industries. This study was focused on the biosurfactant production by Limosilactobacillus fermentum HBUAS62516 for the synthesis of silver nanoparticles. The biosurfactant obtained was characterized as glycolipid using FTIR which showed prominent peaks at 2932.3, 1116.3, and 1084.4 cm-1, indicating major functional groups which was further confirmed using techniques, such as EDS, NMR, and HPLC. Biosurfactant was utilized as the reducing agent for the biosynthesis of silver nanoparticles which was confirmed using UV-Vis spectral measurements that showed maximum absorbance at 421 nm and FTIR revealed peaks at 109 and 665 cm-1, indicating silver nanoparticle formation. EDS confirmed the presence of silver nanoparticles with a mass percentage of 100.00 ± 4.56%. Dynamic light scattering (DLS) and zeta potential were 87.93 nm and - 21 mV, respectively, indicating stability. The nanoparticles showed significant antibiofilm and antioxidant activity (90.1%). The synergistic antibacterial effect of the biosurfactant and nanoparticles was studied against Staphylococcus aureus and Pseudomonas putida, as well as their antifungal activity against Aspergillus niger, with a MIC value of 12.5 μg/mL. Nanoparticles synthesized using biosurfactants obtained from probiotic bacteria can act as alternative therapeutics to treat infections caused by the biofilm-forming bacteria.

Nano-engineered eco-friendly materials for food safety: Chemistry, design and sustainability

The sensitive detection, extraction and analysis of organic compounds such as pharmaceuticals as contaminants in food is very crucial. For this purpose, the effective utilization of sustainable nanomaterials is a promising strategy that combines the benefits of sustainability principles with nanotechnology to ensure the quality and safety of food products. Eco-friendly nanomaterials are distinguished by their exceptional properties, including sustainable synthesis, minimized ecological impact, and production from renewable or waste resources (e.g., cellulose, chitosan, lignin). This review paper elucidates the latest advancements and emerging trends in the development of eco-friendly nanomaterial-based sensor and extraction platforms for the efficient detection and removal of antibiotics as organic contaminants from food samples. The introduction section briefly outlines the significance and benefits of nanomaterials in the construction of sensor platforms. Subsequently, green methodologies for the synthesis of nanomaterials are discussed. Then, the paper progresses with various applications of eco-friendly nanomaterial-based sensor platforms and separation systems towards antibiotic contaminants in food samples. The final section offers conclusions and future perspectives.

Xenosiderophores: bridging the gap in microbial iron acquisition strategies

Microorganisms acquire iron from surrounding environment through specific iron chelators known as siderophores that can be of self-origin or synthesized by neighboring microbes. The latter are termed as xenosiderophores. The acquired iron supports their growth, survival, and pathogenesis. Various microorganisms possess the ability to utilize xenosiderophores, a mechanism popularly termed as 'siderophore piracy' besides synthesizing their own siderophores. This adaptability allows microorganisms to conserve energy by reducing the load of siderogenesis. Owing to the presence of xenosiderophore transport machinery, these microbial systems can be used for targeting antibiotics-siderophore conjugates to control pathogenesis and combat antimicrobial resistance. This review outlines the significance of xenosiderophore utilization for growth, stress management and virulence. Siderogenesis and the molecular mechanism of its uptake by related organisms have been discussed vividly. It focuses on potential applications like disease diagnostics, drug delivery, and combating antibiotic resistance. In brief, this review highlights the importance of xenosiderophores projecting them beyond their role as mere iron chelators.

Controlling Oral Polymicrobial Biofilm Using Usnic Acid on the Surface of Titanium in the Artificial Saliva Media

Background/Objectives: Titanium dental implants, while highly successful, face challenges due to polymicrobial infections leading to peri-implantitis and implant failure. Biofilm formation on implant surfaces is the primary cause of these infections, with factors such as matrix production and cross-kingdom interactions contributing to the microbial accumulation of bacterial and fungal pathogens species. To combat this issue, naturally derived molecules have been reported to overcome the hurdle of antimicrobial resistance against the application of conventional antibiotics and antifungals. Methods: The present study aimed to employ the lichen-derived molecules, usnic acid (UA), to retard the development of biofilms of bacterial and fungal pathogens on the surface of titanium kept in the human artificial saliva (HAS) working as a growth-supporting, host-mimicking media. Results: The minimum inhibitory concentration of UA in HAS towards Candida albicans was >512 µg/mL, whereas against Staphylococcus aureus and Streptococcus mutans, it was determined to be 512 µg/mL. Whereas, in the standard growth media, the MIC value of UA towards S. mutans and S. aureus were 8 and 16 µg/mL; however, against C. albicans, it was 512 µg/mL. UA synergistically enhanced the efficacy of the antibiotics toward bacterial pathogens and the efficacy of antifungals against C. albicans. The antibiofilm results depict the fact that in the HAS, UA significantly reduced both mono-species of S. mutans, S. aureus, and C. albicans and mixed-species biofilm of C. albicans with S. mutans and S. aureus on the surface of the titanium. Conclusions: The present study showed that UA is a promising natural drug that can control oral polymicrobial disease as a result of the application of dental implants.

Human microbiota peptides: important roles in human health

Covering: 1974 to 2024Human microbiota consist of a diverse array of microorganisms, such as bacteria, Eukarya, archaea, and viruses, which populate various parts of the human body and live in a cooperatively beneficial relationship with the host. They play a crucial role in supporting the functional balance of the microbiome. The coevolutionary progression has led to the development of specialized metabolites that have the potential to substitute traditional antibiotics in combating global health challenges. Although there has been a lot of research on the human microbiota, there is a considerable lack of understanding regarding the wide range of peptides that these microbial populations produce. Particularly noteworthy are the antibiotics that are uniquely produced by the human microbiome, especially by bacteria, to protect against invasive infections. This review seeks to fill this knowledge gap by providing a thorough understanding of various peptides, along with their in-depth biological importance in terms of human disorders. Advancements in genomics and the understanding of molecular mechanisms that control the interactions between microbiota and hosts have made it easier to find peptides that come from the human microbiome. We hope that this review will serve as a basis for developing new therapeutic approaches and personalized healthcare strategies. Additionally, it emphasizes the significance of these microbiota in the field of natural product discovery and development.

Exploring the antivirulence potential of phenolic compounds to inhibit quorum sensing in Pseudomonas aeruginosa

Bacteria coordinate gene expression in a cell density-dependent manner in a communication process called quorum sensing (QS). The expression of virulence factors, biofilm formation and enzyme production are QS-regulated phenotypes that can interfere in human health. Due to this importance, there is great interest in inhibiting QS, comprising an anti-virulence strategy. This work aimed to evaluate the effect of selected phenolic compounds on the inhibition of QS-regulated phenotypes in Pseudomonas aeruginosa PAO1, using concentrations that do not interfere in bacterial growth. This is one of the main premises for studying the effect of compounds on QS. Firstly, an in-silico study with the LasR and RhlR proteins of P. aeruginosa by molecular docking of 82 phenolic compounds was performed. Then, a screening with 13 selected phenolic compounds was performed, using biosensor strains P. aeruginosa lasB-gfp and P. aeruginosa rhlA-gfp, which emit fluorescence when the QS system is activated. From this assay, eight compounds were selected and evaluated for inhibition of pyocyanin, rhamnolipids, proteases, elastase, and motility. The compounds variably inhibited the evaluated virulence factors. The greatest inhibitions were observed for swarming motility, achieving inhibition rates of up to 50% for baicalein (500 µM) and curcumin (50 µM). Notably, curcumin showed satisfactory inhibition for all phenotypes even at lower concentrations (12.5 to 50 µM) compared to the other compounds (125 to 500 µM). Four compounds - rosmarinic acid, baicalein, curcumin, and resveratrol - were finally tested against biofilm formation observed by optical microscopy. This study demonstrated that phenolic compounds exhibit strong in silico binding to P. aeruginosa LasR and RhlR proteins and variably inhibit QS-regulated phenotypes in vitro. Although no biofilm inhibition was observed, future studies combining compounds and exploring molecular mechanisms are recommended. These findings highlight the biotechnological potential of phenolic compounds for future applications in the food, clinical, and pharmaceutical fields.

Silver nanoparticles coated with metabolites of Pseudomonas sp. N5.12 inhibit bacterial pathogens and fungal phytopathogens

The synthesis of nanomaterials from PGPB is an exciting approach and it's often used in agriculture as nano-fertilizers and nano-pesticides. The present study reports a new approach to biosynthesis of silver nanoparticles (AgNP), using bacterial metabolites as agents to reduce Ag+, which will remain as coating agents able to prevent microbial growth. Silver NP were biosynthesized using the bacterial metabolites produced by the beneficial strain Pseudomonas sp. N5.12. Optimization of physicochemical parameters (temperature, pH, and AgNO3 concentration) for the synthesis of AgNP was carried out. In each condition, success on AgNP synthesis was determined by UV-Visible spectra showing peaks between 400 and 450 nm. TEM analysis showed that the AgNP are spherical in shape with an average particle size ranging from 13.75 ± 0.47 nm to 20.71 ± 0.43 nm, covered with a unique organic matter corona of bacterial metabolites. The best parameters for AgNP biosynthesis by Pseudomonas sp. N5.12 occurred with 24 h bacterial metabolites, temperature of 37 °C, pH 9 and a ratio of 2:4 (v: v; bacterial supernatant: 1 mM AgNO3). The biosynthesized AgNP inhibited growth of human pathogenic bacteria better than equivalent AgNO3 concentration. Growth of bacterial and fungal phytopathogens was also inhibited with striking effects on Alternaria sp. (74% inhibition) and Stemphylium sp. (52% inhibition), appearing as promising tools to biocontrol fungal diseases in agriculture.

Bacteria-Inspired Synthesis of Silver-Doped Zinc Oxide Nanocomposites: A Novel Synergistic Approach in Controlling Biofilm and Quorum-Sensing-Regulated Virulence Factors in Pseudomonas aeruginosa

Multidrug-resistant Pseudomonas aeruginosa infections pose a critical challenge to healthcare systems, particularly in nosocomial settings. This drug-resistant bacterium forms biofilms and produces an array of virulent factors regulated by quorum sensing. In this study, metal-tolerant bacteria were isolated from a metal-contaminated site and screened for their ability to synthesize multifunctional nanocomposites (NCs). Rapid color changes in the reaction solution evidenced the biotransformation process. The potent isolated Bacillus cereus SASAK, identified via 16S rRNA sequencing and deposited in GenBank under accession number MH885570, facilitated the microbial-mediated synthesis of ZnO nanoparticles and silver-doped ZnO NCs. These biogenic nanocomposites were characterized using UV-VIS-NIR spectroscopy, FTIR, XRD, zeta potential, HRTEM, FESEM, and EDX analyses. At a sub-MIC concentration of 100 µg/mL, 2% Ag-ZnO NCs effectively inhibited virulent factor production and biofilm formation in P. aeruginosa without affecting bacterial growth. Notably, there was a significant reduction in violacein pigment (96.25%), swarming motility, and pyocyanin concentration (1.87 µg/mL). Additionally, biofilm formation (81.1%) and EPS production (83.9%) using P. aeruginosa were substantially hindered, along with reduced extracellular protease activity, as indicated by zone formation (from 2.3 to 1.8 cm). This study underscores the potential of Ag-ZnO NCs as promising agents for combating quorum sensing-mediated virulence in chronic infections caused by multidrug-resistant P. aeruginosa.

ZnO-Rutin nanostructure as a potent antibiofilm agent against Pseudomonasaeruginosa

Pseudomonas aeruginosa is a common human pathogen that is resistant to multiple antibiotics due to its ability to form biofilms. Developing novel nanoformulations capable of inhibiting and removing biofilms offers a promising solution for controlling biofilm-related infections. In this study, we investigated the anti-biofilm activity of rutin-conjugated ZnO nanoparticles (ZnO-Rutin NPs) in pathogenic strains of P. aeruginosa. The synthesized ZnO-Rutin NPs had amorphous shapes with sizes ranging from 14 to 100 nm. The broth microdilution assay revealed that ZnO-Rutin NPs, with an MIC value of 2 mg/mL, exhibit greater antimicrobial activity than ZnO NPs and rutin alone. Based on crystal violet staining, the biofilm inhibition rate by ½ MIC of the conjugated nanoparticles was recorded at above 90 %. The significant reduction in exopolysaccharide (62.75-66.37 %) and alginate (38.3-57.61 %) levels, as well as the formation of thin biofilms in the ZnO-Rutin NP-treated group, confirmed the anti-biofilm potential of these nanoparticles. Additionally, a significant decrease in the metabolic activity and viable cells of mature biofilms was observed after exposure to the conjugated nanoparticles. Furthermore, ZnO-Rutin NPs considerably attenuated the expression of the Las-Rhl quorum-sensing transcriptional regulator genes (lasR and rhlR) in P. aeruginosa by 0.39-0.40 and 0.25-0.42 folds, respectively. This work demonstrated that ZnO-Rutin NPs are remarkably capable of inhibiting the initial stage of biofilm formation and eradicating mature biofilms, suggesting they could be a useful agent for treating P. aeruginosa biofilm-related infections.

Control of Staphylococcus aureus infection by biosurfactant derived from Bacillus rugosus HH2: Strain isolation, structural characterization, and mechanistic insights

Novel antimicrobials are urgently needed to combat methicillin-resistant Staphylococcus aureus (MRSA) infections. This study explores the potential of biosurfactants derived from Bacillus rugosus HH2 as a novel antibacterial agent against MRSA. The biosurfactant, identified as surfactin, demonstrated surface-active properties, reducing surface tension to 37.63 mN/m and lowering contact angles in a concentration-dependent manner. It remained stable across a wide range of pH (4-10), temperatures (30-80 °C), and salinity levels (3-18 %). The biosurfactant inhibited the growth of both methicillin-sensitive S. aureus and MRSA, with minimum inhibitory concentrations ranging from 128 to 256 μg/mL. Additionally, it showed anti-biofilm activity, preventing biofilm formation and dispersing established biofilms. Field-emission scanning electron microscopy revealed that the biosurfactant disrupted bacterial cell membranes, leading to leakage. Furthermore, it reduced the production of virulence factors in S. aureus, including hemolysin and lipase. Transcriptomic analysis indicated downregulation of genes associated with quorum sensing and cell adhesion in MRSA. Molecular docking studies showed strong interactions between surfactin and key MRSA proteins, underscoring its potential to overcome antibiotic resistance. Biocompatibility was confirmed through in vitro cytotoxicity and in vivo phytotoxicity tests. In summary, this study presents surfactin as a promising novel antibacterial agent against MRSA, providing insights into its mechanisms of action.

Effects of nanoparticles on anaerobic, anammox, aerobic, and algal-bacterial granular sludge: A comprehensive review

Nanoparticles (NPs) are of significant interest due to their unique properties, such as large surface area and high reactivity, which have facilitated advancements in various fields. However, their increased use raises concerns about environmental impacts, including on wastewater treatment processes. This review examines the effects of different nanoparticles on anaerobic, anammox, aerobic, and algal-bacterial granular sludge used in wastewater treatment. CeO2 and Ag NPs demonstrated adverse effects on aerobic granular sludge (AGS), reducing nutrient removal and cellular function, while anaerobic granular sludge (AnGS) and anammox granular sludge (AxGS) showed greater resilience due to their higher extracellular polymeric substance (EPS) content. TiO2 NPs had fewer negative effects on algal-bacterial granular sludge (ABGS) than on AGS, as algae played a crucial role in enhancing EPS production and stabilizing the granules. The addition of Fe3O4 NPs significantly enhanced both aerobic and anammox granulation by reducing granulation time, promoting microbial interactions, improving granule stability, and increasing nitrogen removal efficiency, primarily through increased EPS production and enzyme activity. However, Cu and CuO NPs exhibited strong inhibitory effects on aerobic, anammox, and anaerobic systems, affecting EPS structure, cellular integrity, and microbial viability. ZnO NPs demonstrated dose-dependent toxicity, with higher concentrations inducing oxidative stress and reducing performance in AGS and AnGS, whereas AxGS and ABGS were more tolerant due to enhanced EPS production and algae-mediated protection. The existing knowledge gaps and directions for future research on NPs are identified and discussed.

Leveraging bacteria-inspired nanomaterials for targeted controlling biofilm and virulence properties of Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen designated as a high-priority pathogen because of its role in major healthcare-associated and nosocomial infections. Biofilm production by these bacteria is one of the adaptive resistance mechanisms to traditional antibiotics, making treatment challenging, especially for immunocompromised patients. P. aeruginosa also produces a variety of virulence factors, which aid in invasion, adhesion, persistence, and immune system protection. Recent advances in nanotechnology-based therapy, notably the application of bioinspired metal and metal-oxide nanomaterials, have been seen as a viable way to control P. aeruginosa biofilm and virulence. Because of its ease of growth and culture, synthesizing metal and metal-oxide nanomaterials using bacterial species has become one of the most environmentally benign green synthesis options. The application of bacterial-inspired nanomaterials is particularly successful for targeted control of P. aeruginosa infection due to interactions with cell membrane components and transport systems. This paper delves into and provides a complete overview of the application of bacterial-inspired metal and metal-oxide nanomaterials to treat P. aeruginosa infection by targeting biofilm and virulence characteristics. The review focused on synthesizing and applying gold, silver, copper, iron, magnetite, and zinc oxide nanomaterials to mitigate P. aeruginosa biofilm and virulence. The underlying mechanism of these metal and metal-oxide nanoparticles in relation to biofilm and virulence features has also been thoroughly discussed. The current review introduces novel approaches to treating and controlling drug-resistant P. aeruginosa using bacterial-inspired nanomaterials as a targeted therapeutic strategy.

Multifaceted strategies for alleviating Pseudomonas aeruginosa infection by targeting protease activity: Natural and synthetic molecules

Pseudomonas aeruginosa has become a top-priority pathogen in the health sector because it is ubiquitous, has high metabolic/genetic versatility, and is identified as an opportunistic pathogen. The production of numerous virulence factors by P. aeruginosa was reported to act individually or cooperatively to make them robots invasion, adherences, persistence, proliferation, and protection against host immune systems. P. aeruginosa produces various kinds of extracellular proteases such as alkaline protease, protease IV, elastase A, elastase B, large protease A, Pseudomonas small protease, P. aeruginosa aminopeptidase, and MucD. These proteases effectively allow the cells to invade and destroy host cells. Thus, inhibiting these protease activities has been recognized as a promising approach to controlling the infection caused by P. aeruginosa. The present review discussed in detail the characteristics of these proteases and their role in infection to the host system. The second part of the review discussed the recent updates on the multiple strategies for attenuating or inhibiting protease activity. These strategies include the application of natural and synthetic molecules, as well as metallic/polymeric nanomaterials. It has also been reported that a propeptide present in the middle domain of protease IV also attenuates the virulence properties and infection ability of P. aeruginosa.

Roles of Pseudomonas aeruginosa siderophores in interaction with prokaryotic and eukaryotic organisms

Pseudomonas aeruginosa is an opportunistic pathogen that produces two types of siderophores, pyoverdine and pyochelin, that play pivotal roles in iron scavenging from the environment and host cells. P. aeruginosa siderophores can serve as virulence factors and perform various functions. Several bacterial and fungal species are likely to interact with P. aeruginosa due to its ubiquity in soil and water as well as its potential to cause infections in plants, animals, and humans. Siderophores produced by P. aeruginosa play critical roles in iron scavenging for prokaryotic species (bacteria) and eukaryotic hosts (fungi, animals, insects, invertebrates, and plants) as well. This review provides a comprehensive discussion of the role of P. aeruginosa siderophores in interaction with prokaryotes and eukaryotes as well as their underlying mechanisms of action. The evolutionary relationship between P. aeruginosa siderophore recognition receptors, such as FpvA, FpvB, and FptA, and those of other bacterial species has also been investigated.

Production and Antibacterial Activity of Atypical Siderophore from Pseudomonas sp. QCS59 Recovered from Harpachene schimperi

Among sixty-eight pseudomonads, isolate QCS59 from the rhizosphere of H. schimperi was selected based on its siderophore level. Production was optimal in Kings B supplemented with 2% peptone and 0.5% fructose at pH 6.5 and 25 °C for 72 h. Additionally, the threshold potential of iron was found at a concentration of 10 µM. After purification, the acidified siderophore presented a maximum absorption peak of 360 nm, while the neutral form presented a maximum of 414 nm, confirming its pyoverdine (PVD) nature. Furthermore, a major peak appeared at a retention time (RT) of 27.5 min during RP-HPLC, confirming its homogeneity. Interestingly, it demonstrated effective antibacterial activity, especially against Escherichia coli ATCC 8739, with a minimum inhibitory concentration (MIC) of 6.3 µg/mL and a minimum bactericidal concentration (MBC) of 12.5 µg/mL. At ½ the MIC value, it inhibited 82.1% of well-established biofilms of Salmonella enterica. There was an increase in malondialdehyde (MDA) and antioxidative enzymes, especially catalase (CAT) in the treated bacteria because of the peroxidation of membrane lipids and oxidative stress, respectively. SEM proved cellular lysis and surface malformation in most of the treated bacteria. This study concludes that QCS59 siderophore is a promising antibacterial candidate for treating wastewater bacteria and skin pathogens.

Artificial Intelligence-Driven Analysis of Antimicrobial-Resistant and Biofilm-Forming Pathogens on Biotic and Abiotic Surfaces

The growing threat of antimicrobial-resistant (AMR) pathogens to human health worldwide emphasizes the need for more effective infection control strategies. Bacterial and fungal biofilms pose a major challenge in treating AMR pathogen infections. Biofilms are formed by pathogenic microbes encased in extracellular polymeric substances to confer protection from antimicrobials and the host immune system. Biofilms also promote the growth of antibiotic-resistant mutants and latent persister cells and thus complicate therapeutic approaches. Biofilms are ubiquitous and cause serious health risks due to their ability to colonize various surfaces, including human tissues, medical devices, and food-processing equipment. Detection and characterization of biofilms are crucial for prompt intervention and infection control. To this end, traditional approaches are often effective, yet they fail to identify the microbial species inside biofilms. Recent advances in artificial intelligence (AI) have provided new avenues to improve biofilm identification. Machine-learning algorithms and image-processing techniques have shown promise for the accurate and efficient detection of biofilm-forming microorganisms on biotic and abiotic surfaces. These advancements have the potential to transform biofilm research and clinical practice by allowing faster diagnosis and more tailored therapy. This comprehensive review focuses on the application of AI techniques for the identification of biofilm-forming pathogens in various industries, including healthcare, food safety, and agriculture. The review discusses the existing approaches, challenges, and potential applications of AI in biofilm research, with a particular focus on the role of AI in improving diagnostic capacities and guiding preventative actions. The synthesis of the current knowledge and future directions, as described in this review, will guide future research and development efforts in combating biofilm-associated infections.

Anticandidal Activity of a Siderophore from Marine Endophyte Pseudomonas aeruginosa Mgrv7

An endophytic symbiont P. aeruginosa-producing anticandidal siderophore was recovered from mangrove leaves for the first time. Production was optimal in a succinate medium supplemented with 0.4% citric acid and 15 µM iron at pH 7 and 35 °C after 60 h of fermentation. UV spectra of the acidic preparation after purification with Amberlite XAD-4 resin gave a peak at 400 nm, while the neutralized form gave a peak at 360 nm. A prominent peak with RP-HPLC was obtained at RT 18.95 min, confirming its homogeneity. It was pH stable at 5.0-9.5 and thermally stable at elevated temperatures, which encourages the possibility of its application in extreme environments. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) against Candida spp. Were in the range of 128 µg/mL and lower. It enhanced the intracellular iron accumulation with 3.2-4.2-fold (as judged by atomic absorption spectrometry) with a subsequent increase in the intracellular antioxidative enzymes SOD and CAT. Furthermore, the malondialdehyde (MDA) concentration due to cellular lipid peroxidation increased to 3.8-fold and 7.3-fold in C. albicans and C. tropicalis, respectively. The scanning electron microscope (SEM) confirmed cellular damage in the form of roughness, malformation, and production of defensive exopolysaccharides and/or proteins after exposure to siderophore. In conclusion, this anticandidal siderophore may be a promising biocontrol, nonpolluting agent against waterborne pathogens and pathogens of the skin. It indirectly kills Candida spp. by ferroptosis and mediation of hyperaccumulation of iron rather than directly attacking the cell targets, which triggers the activation of antioxidative enzymes.