Bacterial Surface Research Articles

Inorganic Nanoparticles–Driven Self–Assembly of natural small molecules in water for constructing multifunctional nanocapsules against plant diseases

Directly constructing nanoparticles through the self–assembly of natural small molecules in aqueous media presents many opportunities for crop protection; however, this special strategy is hindered by the lack of simple and cost–effective preparation methods to date. Herein, we report a facile strategy for constructing multifunctional natural nanocapsules for treating plant diseases based on the special coassembly of natural small organic molecules and inorganic nanoparticles. In aqueous conditions, uniform curcumin nanocapsules (ZnO@Cur) are assembled through electrostatic interactions, coordination effects and hydration effects as mediated by trace of nanoscale zinc oxide. The nanocapsules obtained can be further modified to enhance stability by introducing a polydopamine coating (ZnO@Cur@PDA). The antibacterial activity of ZnO@Cur@PDA against plant-pathogenic bacteria was better than that of curcumin, ZnO NPs, ZnO@Cur and zinc thiazole in vitro. The nanocapsules effectively kill plant–pathogenic bacteria via tight binding to the bacterial surface, inducing reactive oxygen species accumulation and disrupting bacterial cell walls. ZnO@Cur@PDA display strong activities against rice bacterial blight with protective activity of 64.0 % and curative activity of 62.2%, which is much better than commercial drugs bismerthiazol (protective activity of 33.0 % and curative activity of 38.4%) and zinc thiazole(protective activity of 38.6 % and curative activity of 31.8%). ZnO@Cur@PDA display adequate washing resistance, and low rice plant toxicity; furthermore, they are degradable. Additionally, both the inner cavities and outer surfaces of nanocapsules bear abundant sites and spaces that can be further tuned for loading other pesticide molecules or flexible construct complex multifunctional nanoparticles. Our study should encourage further development in the coassembly of organic and inorganic materials via green processes for effective and tunable nanopesticides.

Highly adhesive and catalytic VOxC nanosheets with strong antibacterial activity

Peroxidase-like nanozymes represent fascinating agents that can treat bacterial infections by oxidative attack. Challengingly, many antibacterial nanozymes only perform well at high concentrations because the low affinity to attach on bacterial surface, short lifetime and working distance for hydroxyl radicals largely limit the applications of antibacterial nanozymes. The potential safety/toxicity should be also considered under an exposure of high concentrations of nanomaterials. In this work, we proposed a “Melee attack” strategy to strikingly enhance antibacterial activity by using peroxidase-like VOxC nanosheets (NSs) that prefer to chemically contact bacterial cell surface. The strategy combines the structure properties of VOxC NSs by coordinating with functional groups on bacteria cell wall with high affinity and the superior peroxidase-like activity of VOxC that can generate hydroxyl radicals for bacterial killing. The VOxC NSs are prepared by controlling the auto-oxidation of V2C NSs, possessing multivalent, ultrathin, flexible and entangled texture as well as good hydrophilicity and biocompatibility. VOxC NSs exhibit efficiently antibacterial activity toward E. coli and S. aureus. This study provides a promising strategy by using adhesive nanozymes in close proximity to the surface of targeted bacteria via chemical bonds, which will inspire the design and application of powerful antibacterial nanozymes with high efficiency.

Alterations of the bacterial ocular surface microbiome are found in both eyes of horses with unilateral ulcerative keratitis.

Next generation sequencing (NGS) studies in healthy equine eyes have shown a more diverse ocular surface microbiota compared to culture-based techniques. This study aimed to compare the bacterial ocular surface microbiota in both eyes of horses with unilateral ulcerative keratitis (UK) with controls free of ocular disease. Conjunctival swabs were obtained from both ulcerated eyes and unaffected eyes of 15 client-owned horses with unilateral UK following informed consent, as well as from one eye of 15 healthy horses. Genomic DNA was extracted from the swabs and sequenced on an Illumina platform using primers that target the V4 region of bacterial 16S rRNA. Data were analyzed using Quantitative Insights Into Molecular Ecology (QIIME2). The ocular surface of ulcerated eyes had significantly decreased species richness compared with unaffected fellow eyes (Chao1 q = 0.045, Observed ASVs p = 0.045) with no differences in evenness of species (Shannon q = 0.135). Bacterial community structure was significantly different between either eye of horses with UK and controls (unweighted UniFrac: control vs. unaffected, p = 0.03; control vs. ulcerated, p = 0.003; unaffected vs. ulcerated, p = 0.016). Relative abundance of the gram-positive taxonomic class, Bacilli, was significantly increased in ulcerated eyes compared with controls (q = 0.004). Relative abundance of the taxonomic family Staphylococcaceae was significantly increased in ulcerated and unaffected eyes compared with controls (q = 0.030). The results suggest the occurrence of dysbiosis in infected eyes and reveal alterations in beta diversity and taxa of unaffected fellow eyes. Further investigations are necessary to better understand the role of the microbiome in the pathophysiology of ocular surface disease.

Potentiating the Systemic Immunity by Bacteria‐Delivered Sting Activation in a Tumor Microenvironment

AbstractStimulator of interferon genes (STING) connects the innate immunity to potent adaptive immunity via multiple pathways, which play a critical role in cancer treatment. Clinical application of STING agonists is mainly restrained due to the metabolic instability caused by intrinsic cyclic dinucleotide ligands. Previously, an orally available non‐nucleotide human STING agonist, MSA‐2 is presented, and to further improve its therapeutic efficacy, this work leverages the nonpathogenic Escherichia coli Nissle 1917 for tumor‐targeted delivery of the STING agonist by coating biocompatible polydopamine on the bacterial surface, termed as PDMN. The engineered bacterial delivery platform holds potential in elevating levels of type I interferon (IFN) along with proinflammatory cytokines and inducing maturation on dendritic cells. Intravenous administration of PDMN with laser irradiation to the tumor region promotes IFN‐β expression in a tumor microenvironment and mounts both the innate and adaptive immune responses, leading to profound regressions of established melanoma and hepatocellular carcinoma in mice. By synergized with anti‐PD‐1 therapy, a substantial long‐lived protective immunity is generated, capable of preventing distant tumor metastases. Hence, this study identifies a STING‐amplified biotherapy to shape the cell‐mediated antitumor immunity, serving as a potential personalized cancer vaccine with enhanced biosafety and immune activation profile for diverse applications.

Immune Evasion Mechanism of Bacteria

The co-evolution of pathogenic bacteria and hosts has led to the development of an array of virulence genes and a set of mechanisms of defense that constitute the immune system. However, successful microbial pathogens have in turn evolved complex and efficient methods to overcome innate and adaptive immune mechanisms, which can result in disease or chronic infections. Different mechanisms are used to subvert and exploit immune systems that are shared between these diverse microbial pathogens. The success of each pathogen is directly dependent on its ability to mount an effective anti-immune response within the infected host, which can ultimately result in acute or chronic infection or pathogen clearance. In this review, some of the mechanisms by which bacterial pathogens evade host immune systems like Biofilm formation and quorum sensing, bacterial surface modulators, inhibition of cytokines, blockade of Acquired Immunity, and other mechanisms are mentioned.

The unique 3D arrangement of macrophage galactose lectin enables Escherichia coli lipopolysaccharide recognition through two distinct interfaces.

Lipopolysaccharides are a hallmark of gram-negative bacteria, and their presence at the cell surface is key for bacterial integrity. As surface-exposed components, they are recognized by immunity C-type lectin receptors present on antigen-presenting cells. Human macrophage galactose lectin binds Escherichia coli surface that presents a specific glycan motif. Nevertheless, this high-affinity interaction occurs regardless of the integrity of its canonical calcium-dependent glycan-binding site. NMR of macrophage galactose-type lectin (MGL) carbohydrate recognition domain and complete extracellular domain revealed a glycan-binding site opposite to the canonical site. A model of trimeric macrophage galactose lectin was determined based on a combination of small-angle X-ray scattering and AlphaFold. A disulfide bond positions the carbohydrate recognition domain perpendicular to the coiled-coil domain. This unique configuration for a C-type lectin orients the six glycan sites of MGL in an ideal position to bind lipopolysaccharides at the bacterial surface with high avidity.

Self-repair and resuscitation of viable injured bacteria in chlorinated drinking water: Achromobacter as an example

Chlorine disinfection for the treatment of drinking water can cause injury to the membrane and DNA of bacterial cells and may induce the surviving injured bacteria into a viable but non-culturable (VBNC) state. It is difficult to monitor viable injured bacteria by heterotrophic plate counting (HPC), and their presence is also easily miscalculated in flow cytometry intact cell counting (FCM-ICC). Viable injured bacteria have a potential risk of resuscitation in drinking water distribution systems (DWDSs) and pose a threat to public health when drinking from faucets. In this study, bacteria with injured membranes were isolated from chlorinated drinking water by FCM cell sorting. The culture rate of injured bacteria varied from 0.08% to 2.6% on agar plates and 0.39% to 6.5% in 96-well plates. As the dominant genus among the five identified genera, as well as an opportunistic pathogen with multiple antibiotic resistance, Achromobacter was selected and further studied. After treatment with chlorine at a concentration of 1.2 mg/L, Achromobacter entered into the intermediate injured state on the FCM plot, and the injury on the bacterial surface was observed by electron microscopy. However, the CTC respiratory activity assay showed that 75.0% of the bacteria were still physiologically active, and they entered into a VBNC state. The injured VBNC Achromobacter in sterile drinking water were resuscitated after approximately 25 h. The cellular repair behavior of injured bacteria was studied by Fourier transform infrared attenuated total reflectance (FTIR-ATR) and comet assays. It was found that DNA injury rather than membrane injury was repaired first. The expression of Ku and ligD increased significantly during the DNA repair period, indicating that non-homologous end-joining (NHEJ) played an important role in repairing DNA double-strand breaks. This study deepened the understanding of the effect of chlorine disinfection on bacterial viability in drinking water and will provide support for the improvement of the chlorine disinfection process for the treatment of drinking water.

Host interactions of novel Crassvirales species belonging to multiple families infecting bacterial host, Bacteroides cellulosilyticus WH2.

Bacteroides, the prominent bacteria in the human gut, play a crucial role in degrading complex polysaccharides. Their abundance is influenced by phages belonging to the Crassvirales order. Despite identifying over 600 Crassvirales genomes computationally, only few have been successfully isolated. Continued efforts in isolation of more Crassvirales genomes can provide insights into phage-host-evolution and infection mechanisms. We focused on wastewater samples, as potential sources of phages infecting various Bacteroides hosts. Sequencing, assembly, and characterization of isolated phages revealed 14 complete genomes belonging to three novel Crassvirales species infecting Bacteroides cellulosilyticus WH2. These species, Kehishuvirus sp. 'tikkala' strain Bc01, Kolpuevirus sp. 'frurule' strain Bc03, and 'Rudgehvirus jaberico' strain Bc11, spanned two families, and three genera, displaying a broad range of virion productions. Upon testing all successfully cultured Crassvirales species and their respective bacterial hosts, we discovered that they do not exhibit co-evolutionary patterns with their bacterial hosts. Furthermore, we observed variations in gene similarity, with greater shared similarity observed within genera. However, despite belonging to different genera, the three novel species shared a unique structural gene that encodes the tail spike protein. When investigating the relationship between this gene and host interaction, we discovered evidence of purifying selection, indicating its functional importance. Moreover, our analysis demonstrated that this tail spike protein binds to the TonB-dependent receptors present on the bacterial host surface. Combining these observations, our findings provide insights into phage-host interactions and present three Crassvirales species as an ideal system for controlled infectivity experiments on one of the most dominant members of the human enteric virome.

A Novel Dual Bacteria-Imprinted Polymer Sensor for Highly Selective and Rapid Detection of Pathogenic Bacteria.

The rapid, sensitive, and selective detection of pathogenic bacteria is of utmost importance in ensuring food safety and preventing the spread of infectious diseases. Here, we present a novel, reusable, and cost-effective impedimetric sensor based on a dual bacteria-imprinted polymer (DBIP) for the specific detection of Escherichia coli O157:H7 and Staphylococcus aureus. The DBIP sensor stands out with its remarkably short fabrication time of just 20 min, achieved through the efficient electro-polymerization of o-phenylenediamine monomer in the presence of dual bacterial templates, followed by in-situ template removal. The key structural feature of the DBIP sensor lies in the cavity-free imprinting sites, indicative of a thin layer of bacterial surface imprinting. This facilitates rapid rebinding of the target bacteria within a mere 15 min, while the sensing interface regenerates in just 10 min, enhancing the sensor's overall efficiency. A notable advantage of the DBIP sensor is its exceptional selectivity, capable of distinguishing the target bacteria from closely related bacterial strains, including different serotypes. Moreover, the sensor exhibits high sensitivity, showcasing a low detection limit of approximately 9 CFU mL-1. The sensor's reusability further enhances its cost-effectiveness, reducing the need for frequent sensor replacements. The practicality of the DBIP sensor was demonstrated in the analysis of real apple juice samples, yielding good recoveries. The integration of quick fabrication, high selectivity, rapid response, sensitivity, and reusability makes the DBIP sensor a promising solution for monitoring pathogenic bacteria, playing a crucial role in ensuring food safety and safeguarding public health.

Genome degradation promotes Salmonella pathoadaptation by remodeling fimbriae-mediated proinflammatory response

ABSTRACT Understanding changes in pathogen behavior (e.g. increased virulence, a shift in transmission channel) is critical for the public health management of emerging infectious diseases. Genome degradation via gene depletion or inactivation is recognized as a pathoadaptive feature of the pathogen evolving with the host. However, little is known about the exact role of genome degradation in affecting pathogenic behavior, and the underlying molecular detail has yet to be examined. Using large-scale global avian-restricted Salmonella genomes spanning more than a century, we projected the genetic diversity of Salmonella Pullorum (bvSP) by showing increasingly antimicrobial-resistant ST92 prevalent in Chinese flocks. The phylogenomic analysis identified three lineages in bvSP, with an enhancement of virulence in the two recently emerged lineages (L2/L3), as evidenced in chicken and embryo infection assays. Notably, the ancestor L1 lineage resembles the Salmonella serovars with higher metabolic flexibilities and more robust environmental tolerance, indicating stepwise evolutionary trajectories towards avian-restricted lineages. Pan-genome analysis pinpointed fimbrial degradation from a virulent lineage. The later engineered fim-deletion mutant, and all other five fimbrial systems, revealed behavior switching that restricted horizontal fecal–oral transmission but boosted virulence in chicks. By depleting fimbrial appendages, bvSP established persistent replication with less proinflammation in chick macrophages and adopted vertical transovarial transmission, accompanied by ever-increasing intensification in the poultry industry. Together, we uncovered a previously unseen paradigm for remodeling bacterial surface appendages that supplements virulence-enhanced evolution with increased vertical transmission.

Asymmetric Structure of Podophage GP4 Reveals a Novel Architecture of Three Types of Tail Fibers

Bacteriophage tail fibers (or called tail spikes) play a critical role in the early stage of infection by binding to the bacterial surface. Podophages with known structures usually possess one or two types of fibers. Here, we resolved an asymmetric structure of the podophage GP4 to near-atomic resolution by cryo-EM. Our structure revealed a symmetry-mismatch relationship between the components of the GP4 tail with previously unseen topologies. In detail, two dodecameric adaptors (adaptors I and II), a hexameric nozzle, and a tail needle form a conserved tail body connected to a dodecameric portal occupying a unique vertex of the icosahedral head. However, five chain-like extended fibers (fiber I) and five tulip-like short fibers (fiber II) are anchored to a 15-fold symmetric fiber-tail adaptor, encircling the adaptor I, and six bamboo-like trimeric fibers (fiber III) are connected to the nozzle. Five fibers I, each composed of five dimers of the protein gp80 linked by an elongated rope protein, are attached to the five edges of the tail vertex of the icosahedral head. In this study, we identified a new structure of the podophage with three types of tail fibers, and such phages with different types of fibers may have a broad host range and/or infect host cells with considerably high efficiency, providing evolutionary advantages in harsh environments.

A very brief note on why bacterial evolution has physiology.

The majority of bacteria live and evolve in surface biofilms. Both growth in biofilms and horizontal transfer of DNA are regulated by quorum-sensing pheromone signals. The common regulation of bacterial surface growth and DNA transfers illustrates how physiology contributes to bacterial evolution.

A signaling complex of adenylate cyclase CyaC of Sinorhizobium meliloti with cAMP and the transcriptional regulators Clr and CycR

BackgroundAdenylate cyclases (ACs) generate the second messenger cyclic AMP (cAMP), which is found in all domains of life and is involved in the regulation of various cell physiological and metabolic processes. In the plant symbiotic bacterium Sinorhizobium meliloti, synthesis of cAMP by the membrane-bound AC CyaC responds to the redox state of the respiratory chain and the respiratory quinones. However, nothing is known about the signaling cascade that is initiated by cAMP produced by CyaC.ResultsHere, the CRP-like transcriptional regulator Clr and the TetR-like regulator CycR (TR01819 protein) were identified to interact with CyaC using the bacterial two-hybrid system (BACTH), co-sedimentation assays, and surface plasmon resonance spectroscopy. Interaction of CycR with Clr, and of CyaC with Clr requires the presence of cAMP and of ATP, respectively, whereas that of CyaC with CycR was independent of the nucleotides.ConclusionThe data implicate a ternary CyaC×CycR×cAMP-Clr complex, functioning as a specific signaling cascade which is formed after activation of CyaC and synthesis of cAMP. cAMP-Clr is thought to work in complex with CycR to regulate a subset of genes of the cAMP-Clr regulon in S. meliloti.

Hypoxia-targeted and spatial-selective tumor suppression by near infrared nanoantenna sensitized engineered bacteria

It is an active research area in the development of engineered bacteria to address the bottleneck issue of hypoxic tumors, which otherwisely possess resistance to chemotherapies, radiotherapies, and photodynamic therapies. Here we report a new method to ablate hypoxic tumors with NIR-nanoantenna sensitized engineered bacteria (NASEB) in a highly effective and dual selective manner. It features engineered E. coli MG1655 (EB) with coatings of lanthanide upconversion nanoparticles (UCNPs) as external antennas on bacterial surface (MG1655/HlyE-sfGFP@UCNP@PEG), enabling NIR laser-switchable generation/secretion of HlyE perforin to kill cancer cells. We have demonstrated that NASEB enrichment on hypoxic tumor sites via their innate chemotactic tendency, in assistance of localized NIR laser irradiation, can suppress tumors with improved efficacy and selectivity, thus minimizing potential side effects in cancer treatment. The NIR-responsive nanoantenna sensitized switching in engineering bacteria is distinct from the previous reports, promising conceptually new development of therapeutics against hypoxic tumors. Statement of significanceTumor hypoxia exacerbates tumor progression, but also reduces the efficacy of conventional chemotherapies, radiotherapies, or photodynamic therapies. Here we develop near infrared Nano Antenna Sensitized Engineered Bacteria (NASEB) to treat hypoxic tumors. NASEB can accumulate and proliferate on hypoxic tumor sites via their innate chemotactic tendency. After receiving NIR laser signals, the upconversion nanoparticles on NASEB surface as antennas can transduce them to blue light for activation of HlyE perforin in the protein factory of EB. Our method features dual selectivity on the tumor sites, contributed by hypoxic tumor homing of anaerobic bacteria and spatial confinement through selective NIR laser irradiation. The concept of NASEB promises to address the challenges of tumor hypoxia for cancer therapies.

Clinical efficacy of ozonated water and photodynamic therapy in non-surgical management of chronic periodontitis: A clinico- microbial study

BackgroundPeriodontitis is a chronic multifactorial inflammatory disease associated with dysbiotic plaque biofilms and characterized by progressive destruction of the tooth-supporting apparatus. Treatment of the periodontitis is a key challenge since the disease occurs due to microbial biofilm which is extremely resistant to host response and antimicrobials. Among non-surgical methods, scaling and root planning (SRP) is considered as the fundamental method and results in the utmost improvements. However, complete elimination of subgingival calculus is difficult. A substitute treatment in inhibition of subgingival microbiota can be attained by ozonated water at a concentration of 0.5–4 mg/L. Lately, laser light therapy has been proposed in periodontal therapy in an endeavor to improve the efficiency and effectiveness of bacterial elimination and root surface debridement. Materials and methods26 patients with chronic periodontitis were selected. The selected arches were randomly divided into two groups: Group-A was subjected to SRP + Ozone-Therapy and Group-B to SRP + Photodynamic-Therapy. Clinical parameters were recorded at baseline, 1&2months. Microbial parameters were recorded at baseline and 2-months. ResultsFor both the groups significant decrease in clinical parameters were seen from baseline to 1 month and further in 2 months. On intergroup comparison of clinical parameters no significant result was found. Both the groups showed significant decrease in microbial parameters was seen from baseline to 2 months. On intergroup comparison of microbial parameters no significant result was found. ConclusionClinically and microbiologically, there was significant difference in both the groups between all time periods (P < 0.001), however there was no significant difference between the two groups at all periods (P > 0.05).

A New In Vitro Blood Flow Model for The Realistic Evaluation of Antimicrobial Surfaces.

Device-associated bloodstream infections can cause serious medical problems and cost-intensive post-infection management, defining a need for more effective antimicrobial coatings. Newly developed coatings often show reduced bacterial colonization and high hemocompatibility in established in vitro tests, but fail in animal studies or clinical trials. The poor predictive power of these models is attributed to inadequate representation of in vivo conditions. Here, we present a new single-pass blood flow model, with simultaneous incubation of the test surface with bacteria and freshly-drawn human blood. The flow model is validated by comparative analysis of a recently developed set of anti-adhesive and contact-killing polymer coatings, and the corresponding uncoated polycarbonate surfaces. The results confirm the model's ability to differentiate the antimicrobial activities of the studied surfaces. Blood activation data correlate with bacterial surface coverage: low bacterial adhesion is associated with low inflammation and hemostasis. Shear stress correlates inversely with bacterial colonization, especially on anti-adhesive surfaces. The introduced model is concluded to enable the evaluation of novel antimicrobial materials under in vivo-like conditions, capturing interactions between bacteria and biomaterials surfaces in the presence of key components of the ex vivo host response. This article is protected by copyright. All rights reserved.

Combined effects of bacteria and antibiotics on surface properties and transport of nanoplastics in porous media

Currently, research on the individual effects of bacteria and antibiotics on the transport of nanoplastics (NPs) in porous media is in its infancy, while research on their combined effect is absent. It is well known that bacteria and antibiotics also interact with each other, so this synergistic transport of bacteria, antibiotics, and NPs in porous media must be very interesting. For exploring this aspect, we investigated the individual and combined effects of bacteria and antibiotics on the transport of polystyrene NPs (PS-NPs) in saturated porous media. Hydrophobicity, roughness, and the Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy were measured and calculated. The PS-NPs' transport in porous media was fitted using a mathematical model. Enhanced roughness and size of PS-NPs with increased bacterial concentration dominated and inhibited the PS-NPs' transport in porous media, although the hydrophilicity of PS-NPs and the energy barrier between PS-NPs and porous media were also increased. An increase in antibiotic concentration reduced the energy barrier between PS-NPs and porous media, thereby decreasing the PS-NPs' transport. Combined effects of bacteria and antibiotics on the PS-NPs' transport were complex and distinct from individual effects, but the mechanisms were clear. Roughness and hydrophilicity of PS-NPs and the DLVO interaction energy between PS-NPs and porous media together influenced this process. In the presence of bacteria, antibiotics could alter the bacterial surface roughness by altering bacterial extracellular polymeric substances, and thus alter the PS-NPs' surface roughness, thereby affecting the PS-NPs' transport in porous media. When antibiotics were present, enhanced bacterial concentration increased the PS-NPs' hydrophilicity and the energy barrier between PS-NPs and porous media, thus promoting the PS-NPs' transport. The findings of this study provided a theoretical basis for clarifying the transport of NPs in porous media under complex environments, facilitating a reduction in environmental pollution of NPs.

Native Pig Neutrophil Products: Insights into Their Antimicrobial Activity.

Cationic antimicrobial peptides are molecules with potential applications for treating infections due to their antimicrobial and immunomodulatory properties. The aim of this work was to explore the antimicrobial activity and mechanisms of action of a porcine neutrophil cathelicidin mixture (MPPN). Gram-positive and Gram-negative bacteria were used to determine the minimum inhibitory concentration (MIC) and experiments of both time-kill kinetics and effects on growth curves were performed. Planar black lipid bilayer conductance was measured to analyze the interaction of MPPN with lipid bilayers. Visualization of bacterial surfaces and membrane alterations was achieved using atomic force microscopy and transmission electron microscopy. The effects on the activity of efflux pumps (EPs) were studied with an intracellular accumulation of acridine orange (AO) assay. In E. coli, MPPN behaves as a bactericide at high concentrations and as a bacteriostatic at lower concentrations. The bacteriostatic effect was also observed for slightly shorter periods in S. enterica. The mixture was not active on S. aureus. The increase in AO accumulation in the presence of MPPN indicates that, at least in E. coli, the mixture causes inhibition of the EP function. Observed and detected variable conductance events demonstrate a strong MPPN effect on lipid bilayers. Damage to the structure of treated E. coli indicates that MPPN induces alterations in the bacterial surface. The use of AMPs capable of inhibiting EP can be seen as a good tool to combat antimicrobial resistance since they could be used alone or in combination with other conventional antibiotics to which bacteria have become resistant.

The Role of Structural Hydrophobicity on Cationic Amphiphilic Aggregation-Induced Emission Photosensitizer-Bacterial Interaction and Photodynamic Efficiency.

The aggregation-induced emission photosensitizer (AIE PS) has stood out as an alternative and competent candidate in bacterial theranostics, particularly with the use of cationic AIE PS in bacterial discrimination and elimination. Most reported work emphasizes the role of electrostatic interaction between cationic AIE PS and negatively charged bacterial surfaces, enabling broad applications from bacterial discrimination to bacterial killing. However, the underlying targeting mechanism and the design rationale of the cationic AIE PS for effective bacterial labeling remain poorly investigated. In this Article, we designed and synthesized a series of cationic amphiphilic AIE PSs with different calculated log P values. Then, we systemically studied the relationship between the hydrophobicity variation of AIE PS and bacterial targeting outcomes, the dose of AIE PS needed to label various species of bacteria, and their photodynamic antibacterial efficiency. The findings in this work provide a better understanding of the unclear AIE PS-bacterial interaction mechanism and some insights into the structural design strategies of cationic amphiphilic AIE PS for better development in bacterial theranostics.

Advances in Understanding the Pathogenesis: Bacterial Surface Glycans as The Virulence Factor and Role in Pathogen Bacteria

Bacterial glycans are essential components of bacterial walls and crucially important cell surface antigens such as lipopolysaccharide and polysaccharide capsules, which act as virulence-causing factors. Polysaccharide capsules in bacteria are naturally composed of recurring oligosaccharides and lipopolysaccharides. LPS is composed of domains that are hydrophobic in nature known as lipid A or endotoxin, which is a nonrepeating oligosaccharide "core", and an O-antigen. Interaction of glycan-receptor is critical in pattern recognition of microorganisms and regulatory signals that perform regular immune cell activities. The true glycan structure is important for collaboration with the immune system of host, as demonstrated by microorganisms that produce polycarbohydrates that mimic host particles in order to evade the immunity of host. Certain bacteria circumvent antibody defences by molecularly mimicking the glycan structures of host and masquerade as "self" to avoid identification by immune system. Phages are the most prevalent biological entities on our planet, and they evolved glycan-binding proteins (GBPs) to bind to bacterial glycans. These proteins are in charge of the breakdown of antibodies and are impervious to harsh conditions where bacteria live for example, the gut of mammals, water, and soil. In order to increase contact with bacterial glycans, the phages manufacture multimeric proteins.