Bacterial Cells Research Articles

Multifaceted toxicity assessment of Au, Ag, and TiO2 nanoparticles synthesized by quorum quenching bacterium Salmonella bongori: Impact on bacterial pathogens, cancer cells, mosquitoes, zebrafish, and brine shrimp

The present study pertained to evaluate biological properties of the nanoparticles synthesised using quorum quenching-QQ Salmonella bongori-SB. The QQ potential of SB was confirmed through streaking (halos) and diffusing cell-free-supernatant (decolored) against Chromobacterium violaceum-CV and significant antagonistic effect on Pseudomonas aeruginosa-PA and P. fluorescens-PF. HPLC peaks confirmed the degradation of 3-oxo-C12-HSL (3.185) by QQ-SB at 2.579 and 2.924. The morphological characteristics-(crystallite size; shape with size range), and significant antibacterial-ABA, antibiofilm-ABFA and anti-proliferative-APA (with IC50 values on HeLa and A549 cells) activities of different-NPs were recorded as follows: SB-AuNPs (31.61 nm; aggregated spherical (13.66–18.38 nm)) resulted in good ABA (on PF and Serratia marcescens), ABFA (on PF) and APA (IC50: 33.79 and 33.74 µgmL−1). Similarly, SB-AgNPs (19.83 nm; clustered spherical; 4.81–8.58 nm) showed the most-significant ABA (CV and PF), ABFA (PA, CV and PF) and APA (IC50: 24.57, and 22.7 µgmL−1). Whereas, SB-TiO2NPs (47.33 nm; spherical with 75.13 nm) did not produced significant activities. Overall, the first report on the QQ potential of SB and its NPs emerged to be good candidate that might combat the pragmatic difficulties against MDR strains and drug failures in cancer treatments. Therefore, standardizing its applications in quorum sensing inhibitory mechanisms and anti-proliferative effects is warranted.

Integrated remediation and detoxification of triclocarban-contaminated water using waste-derived biochar-immobilized cells by long-term column experiments

Triclocarban (TCC), an antibacterial agent commonly used in personal care products, is one of the top ten contaminants of emerging concern in various environmental media, including soil and contaminated water in vadose zone. This study aimed to investigate TCC-contaminated water remediation using biochar-immobilized bacterial cells. Pseudomonas fluorescens strain MC46 (MC46), an efficient TCC-degrading isolate, was chosen, whereas agro-industrial carbonized waste as biochar was directly used as a sustainable cell immobilization carrier. According to the long-term TCC removal performance results (160 d), the biochar-immobilized cells consistently exhibited high TCC removal efficiencies (84–97%), whereas the free MC46 removed TCC for 76–94%. At 100 days, the detachment of the MC46 cells from the immobilized cell column was observed. The micro-Fourier-transform infrared spectroscopy results indicated that extracellular polymeric substance (EPS) was produced, but polysaccharide and protein fractions were washed out of the column. The lipid fraction of EPS adhered to the biochar, promoting TCC sorption for long-term treatment. The shortening of MC46 cells improved the tolerance of TCC toxicity. The TCC-contaminated water was successfully detoxified by the biochar-immobilized MC46 cells. Overall, the waste-derived biochar-immobilized cell system proposed in this study for the removal of emerging contaminants, including TCC, is efficient, economical, and aligned with the sustainable development concept of value-added utilization of waste.

Antibacterial activity of t-cinnamaldehyde: An approach to its mechanistic principle towards enterohemorrhagic Escherichia coli (EHEC)

BackgroundCompounds of natural origin are potent source of drugs with unique mechanisms of action. Among phytochemicals, trans-cinnamaldehyde (t-CA) exhibits a wide range of biological activity, thus has been used for centuries to fight bacterial and fungal infections. However, the molecular basis of these properties has not been fully covered. Considering that difficult-to-control infections are becoming a rising global problem, there is a need to elucidate the molecular potential of t-CA. PurposeTo evaluate the antibacterial activity of t-CA against Shiga-toxigenic E. coli strains and elucidate its mechanism of action based on the inhibition of the virulence factor expression. MethodsThe antimicrobial potential of t-CA was assessed with two-fold microdilution and time-kill assays. Further evaluation included bioluminescence suppression assays, quantification of reactive oxygen species (ROS) and assessment of NAD+/NADH ratios. Morphological changes post t-CA exposure were examined using transmission electron microscopy. RNA sequencing and radiolabeling of nucleotides elucidated the metabolic alterations induced by t-CA. Toxin expression level was monitored through the application of fusion proteins, monitoring of bacteriophage development, and fluorescence microscopy studies. Lastly, the therapeutic efficacy in vivo was assessed using Galleria mellonella infection model. ResultsA comprehensive study of t-CA's bioactivity showed unique properties affecting bacterial metabolism and morphology, resulting in significant bacterial cell deformation and effective virulence inhibition. Elucidation of the underlying mechanisms indicated that t-CA activates the global regulatory system, the stringent response, manifested by its alarmone, (p)ppGpp, overproduction mediated by the RelA enzyme, thereby inhibiting bacterial proliferation. Intriguingly, t-CA effectively downregulates Shiga toxin gene expression via alarmone molecules, indicating its potential for therapeutic effect. In vivo validation demonstrated a significant improvement in larval survival rates post- t-CA treatment with 50 mg/kg (p < 0.05), akin to the efficacy observed with azithromycin, thus indicating its effectiveness against EHEC infections (p < 0.05). ConclusionsCollectively, these results reveal the robust antibacterial capabilities of t-CA, warranting its further exploration as a viable anti-infective agent.

Long-term tracking of the microbiology of uranium-amended water-saturated bentonite microcosms: A mechanistic characterization of U speciation

Deep geological repositories (DGRs) stand out as one of the optimal options for managing high-level radioactive waste (HLW) such as uranium (U) in the near future. Here, we provide novel insights into microbial behavior in the DGR bentonite barrier, addressing potential worst-case scenarios such as waste leakage (e.g., U) and groundwater infiltration of electron rich donors in the bentonite. After a three-year anaerobic incubation, Illumina sequencing results revealed a bacterial diversity dominated by anaerobic and spore-forming microorganisms mainly from the phylum Firmicutes. Highly U tolerant and viable bacterial isolates from the genera Peribacillus, Bacillus, and some SRB such as Desulfovibrio and Desulfosporosinus, were enriched from U-amended bentonite. The results obtained by XPS and XRD showed that U was present as U(VI) and as U(IV) species. Regarding U(VI), we have identified biogenic U(VI) phosphates, U(UO2)·(PO4)2, located in the inner part of the bacterial cell membranes in addition to U(VI)-adsorbed to clays such as montmorillonite. Biogenic U(IV) species as uraninite may be produced as result of bacterial enzymatic U(VI) reduction. These findings suggest that under electron donor-rich water-saturation conditions, bentonite microbial community can control U speciation, immobilizing it, and thus enhancing future DGR safety if container rupture and waste leakage occurs.

Characterization of a Ligilactobacillus salivarius Strain Isolated from a Cheese Seal Which Was Last Used in 1936.

Cheesemaking played a pivotal role in the life of the Pyrenean villages where cheese was a most prized commodity and the subject of much local competition. In one of them (Sasa de Sobrepuerto), Mrs. Sebastiana Palacio decided in 1877 to label all the cheeses made in her household with a seal to differentiate them from those made by other local producers. The cheese seal was last used in 1936 and, since then, it has been kept under excellent storage conditions. Since well-preserved cheese seals are rare, and bacterial cells may survive desiccation for long periods, the objective of this work was to isolate and characterize any lactic acid bacteria that survived in the seal. Analysis of the milky crust material revealed the presence of sheep caseins. Culture-based analysis led to the isolation of a strain of Bacillus licheniformis and a strain of Ligilactobacillus salivarius (L. salivarius SP36). The latter was characterized in vitro for safety and dairy-related functional properties. Its genome encodes several genes involved in protein, peptide, and amino acid catabolism, and flavor. Overall, the phenotypic and genetic features of this strain support a high potential for being used as adjunct culture in cheesemaking.

Effect of Enterococin – Zinc Oxide Nanoparticles on Gene Expression of rsbA Swarming Genes in Proteus mirabilis isolation Catheter urine.

Urinary tract infections linked to catheters are believed to be caused most frequently by Proteus mirabilis. It produces urease, which greatly increases the potency of catheter occlusion caused by swarming. Pathogenic bacteria use swarming as one of their main virulence mechanisms to evade antibiotics; as a result, there is an increasing need to develop novel antibiotic substitutes. Investigating the possible antibiofilm capabilities of artificial zinc oxide nanoparticles (ZnO NPs) made from E. Faecium was the aim of this study. By generating reductive enzymes, bacterial cells are able to catalyze the biosynthesis process. Bacteriocin-like inhibitory substance (BLIS) was used to create the nanoparticles. AFM, TEM, FESEM, and other analytical tools were used to characterize the synthesized zinc nanoparticles and determine the chemical and physical characteristics of the products. Weak swarming is shown by microorganisms that develop strong swarming. After incubation, the ZnO nanoparticles were incubated for 24 or 48 hours at 37°C at a sub-MIC of 32 µg/ml. After these isolates were treated with zinc nanoparticles, downregulation of rsbA expression was detected via real-time PCR compared to that in the untreated isolates. Zinc oxide nanoparticles can serve as antibacterial agents in a concentration-dependent manner, according to all of the study's findings. This was demonstrated by the notable downregulation of rsbA gene expression, which effectively inhibits the production of biofilms and swarming motility. This was demonstrated by their noteworthy downregulation of rsbA gene expression, which effectively promoted swarmed motility.

Tea polyphenol/ Pluronic F127 complex for bacterial polluted water purification

Removal of bacteria from biological contaminated water is of great importance to the control of waterborne diseases. Herein, a simple and green method to purify bacterial infectant water was developed using two food supplements. Tea polyphenol (TP)/F127 complex was proved to remove nearly all bacteria from contaminated water by centrifugation. Without facilities, gravity sedimentation could isolate most of bacteria with high efficiency. The hydrogen bonds induced the formation of oleaginous precipitation composed of TP, F127, and bacterial cells with hydrophilic interior to encapsulate bacteria and hydrophobic surface against bacteria leaking out. The good biosafety of sedimentation agents, easy operation and common facilities implied this method could be used as a convenient approach to water purify, especially in the wilds and developing countries.

MassARRAY: a high-throughput solution for rapid detection of foodborne pathogens in real-world settings.

Bacterial foodborne pathogens pose a substantial global public health concern, prompting government agencies and public health organizations to establish food safety guidelines and regulations aimed at mitigating the risk of foodborne illness. The advent of DNA-based amplification coupled with mass spectrometry, known as MassARRAY analysis, has proven to be a highly precise, sensitive, high-throughput, and cost-effective method for bacterial detection. This study aimed to develop, validate, and evaluate a MassARRAY-based assay for the detection and identification of significant enteropathogenic bacteria. The MassARRAY-based assay was developed for the detection of 10 crucial bacterial foodborne pathogens, including Campylobacter coli, Campylobacter jejuni, Clostridium perfringens, Escherichia coli, Enterococcus faecalis, Enterococcus faecium, Listeria monocytogenes, Salmonella spp., Shigella spp., and Staphylococcus aureus. The assay was optimized using the reference gDNA (n = 19), followed by validation using gDNA (n = 85) of reference and laboratory isolates. Additionally, the evaluation of the assay's reaction using a mixture of gDNA from all nine targeted species was performed. The limit of detection of the developed MassARRAY-based assay was determined using bacterial cells. Moreover, the validation method for field samples was evaluated by comparing it with standard microbiological testing methods routinely analyzed. The developed MassARRAY-based assay demonstrated 100% concordance with known bacterial pure cultures. The assay's reaction using a mixture of gDNA from all nine targeted species revealed the MassARRAY's capability to detect all targeted species in a single assay with the lowest concentration of 1 ng/μL of gDNA. The limits of detection of the assay range from 357 ± 101 to 282,000 ± 79,196 cells. Moreover, the validation of the assay in field samples revealed a 100% correlation between the data obtained from the standard microbiological method and the MassARRAY-based assay. These findings suggested that the developed MassARRAY-based assay exhibited the excellence in high-throughput detection of foodborne bacterial pathogens with high accuracy, reliability, and potential applicability within real-world field samples.

Adhesive interactions within microbial consortia can be differentiated at the single-cell level through expansion microscopy.

Investigating microbe-microbe interactions at the single-cell level is critical to unraveling the ecology and dynamics of microbial communities. In many situations, microbes assemble themselves into densely packed multi-species biofilms. The density and complexity pose acute difficulties for visualizing individual cells and analyzing their interactions. Here, we address this problem through an unconventional application of expansion microscopy, which allows for the 'decrowding' of individual bacterial cells within a multispecies community. Expansion microscopy generally has been carried out under isotropic expansion conditions and used as a resolution-enhancing method. In our variation of expansion microscopy, we carry out expansion under heterotropic conditions; that is, we expand the space between bacterial cells but not the space within individual cells. The separation of individual bacterial cells from each other reflects the competition between the expansion force pulling them apart and the adhesion force holding them together. We employed heterotropic expansion microscopy to study the relative strength of adhesion in model biofilm communities. These included mono and dual-species Streptococcus biofilms, and a three-species synthetic community (Fusobacterium nucleatum, Streptococcus mutans, and Streptococcus sanguinis) under conditions that facilitated interspecies coaggregation. Using adhesion mutants, we investigated the interplay between F. nucleatum outer membrane protein RadD and different Streptococcus species. We also examined the Schaalia-TM7 epibiont association. Quantitative proximity analysis was used to evaluate the separation of individual microbial members. Our study demonstrates that heterotropic expansion microscopy can 'decrowd' dense biofilm communities, improve visualization of individual bacterial members, and enable analysis of microbe-microbe adhesive interactions at the single-cell level.

Structural and thermodynamic characterization of a highly amyloidogenic dimer of transthyretin involved in a severe cardiomyopathy

Transthyretin (TTR) is a homotetrameric protein involved in the transport of thyroxine. More than 150 different mutations have been described in the TTR gene, several of them associated with familial amyloid cardiomyopathy (FAC). Recently, our group described a new variant of TTR in Brazil, namely A39D-TTR, which causes a severe cardiac condition. Position 39 is in the AB loop, a region of the protein that is located within the thyroxine-binding channels and is involved in tetramer formation. In the present study we solved the structure and characterize the thermodynamic stability of this new variant of TTR using urea and high hydrostatic pressure (HHP). Interestingly, during the process of purification, A39D-TTR turned out to be a dimer and not a tetramer, a variation that might be explained by the close contact of the four aspartic acids at position 39, where they face each other inside the thyroxine channel. In the presence of sub-denaturing concentrations of urea, bis-ANS binding and dynamic light scattering revealed A39D-TTR in the form of a molten-globule dimer. Co-expression of A39D and WT isoforms in the same bacterial cell did not produce heterodimers or heterotetramers, suggesting that somehow a negative charge at the AB loop precludes tetramer formation. A39D-TTR proved to be highly amyloidogenic, even at mildly acidic pH values where WT-TTR does not aggregate. Interestingly, despite being a dimer, aggregation of A39D-TTR was inhibited by diclofenac, which binds to the thyroxine channel in the tetramer, suggesting the existence of other pockets in A39D-TTR able to accommodate this molecule.

Cur@ZIF-8@BA nanomaterials with pH-responsive and photodynamic therapy properties promotes antimicrobial activity.

Antimicrobial photodynamic therapy (aPDT) has emerged as a highly promising strategy for non-antibiotic treatment of infections due to its unique advantages in efficient bactericidal action and reduction of drug resistance. The natural photosensitizing properties of curcumin (Cur) are widely acknowledged; however, its limited bioavailability has impeded its practical application. In this study, we developed a nanomaterial called Cur@ZIF-8@BA by encapsulating Cur within ZIF-8 and modifying the surface with boric acid (BA). The Cur@ZIF-8@BA exhibits pH-responsive properties and enhances bacterial binding, thereby effectively promoting photodynamic therapy. Moreover, its antibacterial activity against E. coli, Staphylococcus aureus and A. baumannii is significantly increased in the presence of light compared to a dark environment. The mechanism behind this may be that BA increases the affinity of Cur@ZIF-8@BA towards bacteria, and making released Zn2+ and BA from the nanomaterial increase bacterial cell membrane permeability. This facilitates efficient delivery of Cur into bacterial cells, resulting in generation of abundant reactive oxygen species (ROS) and subsequent bactericidal activity. In conclusion, our prepared Cur@ZIF-8@BA holds great promise as a photodynamically mediated antimicrobial strategy.

Biologically inspired nanoformulations for the control of bacterial canker pathogens Clavibacter michiganensis subsp. michiganensis and subsp. capsici

Clavibacter michiganensis subsp. michiganensis (Cmm) and C. michiganensis subsp. capsici (Cmc) are phytopathogenic bacteria that cause bacterial canker disease in tomatoes and peppers, respectively. Bacterial canker disease poses serious challenges to solanaceous crops, causing significant yield losses and economic costs. Effective management necessitates the development of sustainable control strategies employing nanobiotechnology. In this study, the antibacterial effects of four Aspergillus sojae-mediated nanoformulations, including cobalt oxide nanoparticles (Co3O4 NPs), zinc oxide nanoparticles (ZnO NPs), cobalt ferrite nanoparticles (CoFe2O4 NPs), and CoFe2O4/functionalized multi-walled carbon nanotube (fMWCNT) bionanocomposite, were evaluated against Cmm and Cmc. The diameters of the zone of inhibition of A. sojae-mediated Co3O4 NPs, ZnO NPs, CoFe2O4 NPs, and CoFe2O4/fMWCNT bionanocomposite against Cmm and Cmc were 23.60 mm, 22.09 mm, 27.65 mm, 22.51 mm, and 19.33 mm, 17.66 mm, 21.64 mm, 18.77 mm, respectively. The broth microdilution assay was conducted to determine the minimal inhibitory and bactericidal concentrations. The MICs of Co3O4 NPs, ZnO NPs, CoFe2O4 NPs, and CoFe2O4/fMWCNT bionanocomposite against Cmm were 2.50 mg/mL, 1.25 mg/mL, 2.50 mg/mL, and 2.50 mg/mL, respectively. While, their respective MBCs against Cmm were 5.00 mg/mL, 2.50 mg/mL, 5.00 mg/mL, and 5.00 mg/mL. The respective MICs of Co3O4 NPs, ZnO NPs, CoFe2O4 NPs, and CoFe2O4/fMWCNT bionanocomposite against Cmc were 2.50 mg/mL, 1.25 mg/mL, 5.00 mg/mL, and 5.00 mg/mL. While, their respective MBCs against Cmc were 5.00 mg/mL, 2.50 mg/mL, 10.00 mg/mL, and 10.00 mg/mL. The morphological and ultrastructural changes of Cmm and Cmc cells were observed using field-emission scanning and transmission electron microscopy before and after treatment with sub-minimal inhibitory concentrations of the nanoformulations. Nanoformulation-treated bacterial cells became deformed and disrupted, displaying pits, deep cavities, and groove-like structures. The cell membrane detached from the bacterial cell wall, electron-dense particles accumulated in the cytoplasm, cellular components disintegrated, and the cells were lysed. Direct physical interactions between the prepared nanoformulations with Cmm and Cmc cells might be the major mechanism for their antibacterial potency. Further research is required for the in vivo application of the mycosynthesized nanoformulations as countermeasures to combat bacterial phytopathogens.

Antibacterial activity and mechanism of luteolin isolated from Lophatherum gracile Brongn. against multidrug-resistant Escherichia coli.

Infections caused by multidrug-resistant (MDR) bacteria have become a major challenge for global healthcare systems. The search for antibacterial compounds from plants has received increasing attention in the fight against MDR bacteria. As a medicinal and edible plant, Lophatherum gracile Brongn. (L. gracile) has favorable antibacterial effect. However, the main antibacterial active compound and its antimicrobial mechanism are not clear. Here, our study first identified the key active compound from L. gracile as luteolin. Meanwhile, the antibacterial effect of luteolin was detected by using the broth microdilution method and time-kill curve analysis. Luteolin can also cause morphological structure degeneration and content leakage, cell wall/membrane damage, ATP synthesis reduction, and downregulation of mRNA expression levels of sulfonamide and quinolones resistance genes in multidrug-resistant Escherichia coli (MDR E. coli). Furthermore, untargeted UPLC/Q-TOF-MS-based metabolomics analysis of the bacterial metabolites revealed that luteolin significantly changed riboflavin energy metabolism, bacterial chemotaxis cell process and glycerophospholipid metabolism of MDR E. coli. This study suggests that luteolin could be a potential new food additive or preservative for controlling MDR E. coli infection and spread.

Mechanism of antibacterial phytoconstituents: an updated review.

The increase of multiple drug resistance bacteria significantly diminishes the effectiveness of antibiotic armory and subsequently exaggerates the level of therapeutic failure. Phytoconstituents are exceptional substitutes for resistance-modifying vehicles. The plants appear to be a deep well for the discovery of novel antibacterial compounds. This is owing to the numerous enticing characteristics of plants, they are easily accessible and inexpensive, extracts or chemicals derived from plants typically have significant levels of action against infections, and they rarely cause serious adverse effects. The enormous selection of phytochemicals offers very distinct chemical structures that may provide both novel mechanisms of antimicrobial activity and deliver us with different targets in the interior of the bacterial cell. They can directly affect bacteria or act together with the crucial events of pathogenicity, in this manner decreasing the aptitude of bacteria to create resistance. Abundant phytoconstituents demonstrate various mechanisms of action toward multi drug resistance bacteria. Overall, this comprehensive review will provide insights into the potential of phytoconstituents as alternative treatments for bacterial infections, particularly those caused by multi drug resistance strains. By examining the current state of research in this area, the review will shed light on potential future directions for the development of new antimicrobial therapies.

Modification of The Bacterial Abundance Properties of Water by Immersed Non-Activated Charcoal

The present studies aim at reducing the planktonic bacterial load in drinking water using non-activated charcoal. The evaluation is dependent on the incubation time and the different physiological states of the bacterial cells. Three bacteria (Vibrio cholerae, Escherichia coli and Staphylococcus aureus) and two charcoal substrates (Okan and Tali) were used for the experimentation. The Bacteria adhered to charcoal fragments in varying degrees. Overall, the concentrations of fixed Vibrio cholerae reached 53.4x107 CFU/cm2 and 39.6x107 CFU/cm2 after 9 hours of contact in exponential phase on the Okan and Tali respectively. Those of fixed Staphylococcus aureus reached 5.8x106 CFU/cm2 after 3 hours of contact in exponential phase and 3.4x106 CFU/cm2 after 3 and 6 hours of contact in the same phase, on the Okan and the Tali, respectively. The highest abundances of Escherichia coli adhered to the charcoal fragments were 50.4x107 CFU/cm² on Okan and 53.2x107 CFU/cm² on Tali after 9 hours of contact in the exponential phase. The highest adsorption coefficient (639.06 adhered cells/cm2) was noted on Okan in the exponential phase with Vibrio cholerae cells; and the lowest (1.02 adhered cells/cm2) on Tali in stationary phase with Staphylococcus aureus. The incubation time significantly (P&lt;0.01) influenced the adhesion of bacterial cells to charcoal substrates. Although the adsorption capacity and intensity of Okan were relatively higher, the comparison of the adsorption potential of the two substrates considered did not reveal any significant difference (P&gt;0.05), reflecting the absence of the influence of the physical properties of these substrates on cell retention.

Evidence for immune priming specificity and cross-protection against sympatric and allopatric Vibrio splendidus strains in the oyster Magalana (Crassostrea) gigas

Infections with pathogenic Vibrio strains are associated with high summer mortalities of Pacific oysters Magalana (Crassostrea) gigas, affecting production worldwide. This raises the question of how M. gigas cultures can be protected against deadly Vibro infection. There is increasing experimental evidence of immune priming in invertebrates, where previous exposure to a low pathogen load boosts the immune response upon secondary exposure. Priming responses, however, appear to vary in their specificity across host and parasite taxa. To test priming specificity in the Vibrio – M. gigas system, we used two closely related Vibrio splendidus strains with differing degrees of virulence towards M. gigas. These V. splendidus strains were either isolated in the same location as the oysters (sympatric, opening up the potential for co-evolution) or in a different location (allopatric). We extracted cell-free haemolymph plasma from infected and control oysters to test the influence of humoral immune effectors on bacterial growth in vitro. While addition of haemolypmph plasma in general promoted growth of both strains, priming by an exposure to a sublethal dose of bacterial cells lead to inhibitory effects against a subsequent challenge with a potentially lethal dose in vitro. Inhibitory effects and immune priming was strongest when oysters had been primed with the sympatric Vibrio strain, but inhibitory effects were seen both when challenged with the sympatric as well as against allopatric V. splendidus, suggesting some degree of cross protection. The stronger immune priming against the sympatric strain suggests that priming could be more efficient against matching local strains potentially adding a component of local adaptation or co-evolution to immune priming in oysters. These in vitro results, however, were not reflected in the in vivo infection data, where we saw increased bacterial loads following an initial challenge. This discrepancy might suggests that that it is the humoral part of the oyster immune system that produces the priming effects seen in our in vitro experiments.

Alder‐Longo Method Derived Cationic Porphyrin‐Based Porous Polymer as Physical Antibacterial Agent for the Bacteria‐Infected Wound Synergy Therapy

AbstractThe widespread of drug‐resistant genes has greatly exacerbated the difficulty for the effectively tre atment of diseases associated with bacterial infections. The ineffectiveness of antibiotics poses great challenges to the development of new antimicrobial agents, especially those does not cause bacterial resistance. Herein, a cation porous organic polymer (CPOP) denoted as BDPP, was facilely prepared via the Alder‐Longo method skipping the tedious porphyrin‐bearing monomer synthesis procedure. The repeated porphyrin units endowed excellent photoactivity with the porous skeletons, and the inherent cations significantly improved the binding ability of BDPP with the bacterial cell membrane. As a result, the as‐synthesized POPs could be used as a physical broad spectrum sterilization agent, amalgamating the cation and photothermal therapy to exert synergistic amplified antibacterial effects. In vivo assay demonstrated BDPP with good biocompatibility, could also significantly promote the healing of wounds with bacteria‐infection. This work paves a facile way for the rational construction of material‐based antibacterial agent for the bacteria inactivation.

Screening and characterization of antagonistic Streptomyces sp. JS20 from marine sediment in Vaan Island

In the present study, we have isolated twenty four different Actinomycetia strains from marine sediment in Vaan Island, Tuticorin district (8.83639°N/78.21047°E), Tamil Nadu, India. Among these, the isolate JS20 has been identified as Streptomyces sp. JS20 by 16S rRNA phylogenetic analysis, which exhibited prominent antibacterial activity against panel of WHO priority pathogens mostly, MRSA a clinical pathogen. The bioassay guided fractionation dependent active compound exhibits RT at 3.0 with maximum UV absorption of 250 nm. Furthermore, FT-IR, 1H NMR, 13C NMR and LC-MS spectral analysis confirms the existence of polyketide metabolites with molecular mass of m/z 380.74 [M+Na]+ and m/z 397.00 [M+K]+ adducts. Minimum Inhibitory Concentration (MIC) and Minimum Bacterial Concentration (MBC) value of the purified compound against MRSA was found to be 7.81 µg/mL and 125 µg/mL respectively. Additionally, the anti-MRSA campaign of the purified compound was upheld qualitatively using the high content screening (HCS) and quantitatively by Flow Cytometry (FACS) analysis which indicates concentration of bactericidal activity increases when the concentration of the purified compound was increased. The action of bioactive compound was determined by cell morphology disruption on MRSA bacterial cells as results, the cytoplasm cellular contents and ATP leaky were ahead. Apart from these studies, NaCl tolerant, the multiple passage studies and post antibiotic effect of bioactive compound has been evaluated against the MRSA. Hence, the study revealed that the bioactive compound from the Streptomyces sp. JS20 can be used as a lead compound to inhibit the MRSA in future.

Synthesis of high-performance antibacterial agent based on incorporated vancomycin into MOF-modified lignin nanocomposites

The alarming rise in antibiotic resistance necessitates urgent action, particularly against the backdrop of resistant bacteria evolving to render conventional antibiotics less effective, leading to an increase in morbidity, mortality, and healthcare costs. Vancomycin-loaded Metal-Organic Framework (MOF) nanocomposites have emerged as a promising strategy in enhancing the eradication of pathogenic bacteria. This study introduces lignin as a novel synergistic agent in Vancomycin-loaded MOF (Lig-Van-MOF), which substantially enhances the antibacterial activity against drug-resistant bacteria. Lig-Van-MOF exhibits six-fold lower minimum inhibitory concentration (MICs) than free vancomycin and Van-MOF with a much higher antibacterial potential against sensitive and resistant strains of Staphylococcus aureus and Escherichia coli. Remarkably, it reduces biofilms of these strains by over 85 % in minimal biofilm inhibitory concentration (MBIC). Utilization of lignin to modify surface properties of MOFs improves their adhesion to bacterial membranes and boosts the local concentration of Reactive Oxygen Species (ROS) via unique synergistic mechanism. Additionally, lignin induces substantial cell deformation in treated bacterial cells. It confirms the superior bactericidal properties of Lig-Van-MOF against Staphylococcus species, underlining its significant potential as a bionanomaterial designed to combat antibiotic resistance effectively. This research paves the way for novel antibacterial platforms that optimize cost-efficiency and broaden microbial resistance management applications.

Lavandula angustifolia Essential Oil Inhibits the Ability of Fusobacterium nucleatum to Produce Volatile Sulfide Compounds, a Key Components in Oral Malodor.

Oral malodor still constitutes a major challenge worldwide. A strong effort is invested in eliminating volatile sulfur compound-producing oral bacteria through organic natural products such as essential oils. Fusobacterium nucleatum is a known volatile sulfur compound-producing bacteria that inspires oral malodor. The aim of the present study was to test the effect of lavender essential oil on the bacterium's ability to produce volatile sulfide compounds, the principal components of oral malodor. Lavender (Lavandula angustifolia) essential oil was extracted by hydrodistillation and analyzed using GC-MS. The minimal inhibitory concentration (MIC) of lavender essential oil on Fusobacterium nucleatum was determined in a previous trial. Fusobacterium nucleatum was incubated anaerobically in the presence of sub-MIC, MIC, and above MIC concentrations of lavender essential oil, as well as saline and chlorhexidine as negative and positive controls, respectively. Following incubation, volatile sulfur compound levels were measured using GC (Oralchroma), and bacterial cell membrane damage was studied using fluorescence microscopy. Chemical analysis of lavender essential oil yielded five main components, with camphor being the most abundant, accounting for nearly one-third of the total lavender essential oil volume. The MIC (4 µL/mL) of lavender essential oil reduced volatile sulfur compound secretion at a statistically significant level compared to the control (saline). Furthermore, the level of volatile sulfur compound production attributed to 1 MIC of lavender essential oil was in the range of the positive control chlorhexidine with no significant difference. When examining bacterial membrane damage, 2 MIC of lavender essential oil (i.e., 8 µL/mL) demonstrated the same, showing antibacterial membrane damage values comparative to chlorhexidine. Since lavender essential oil was found to be highly effective in hindering volatile sulfur compound production by Fusobacterium nucleatum through the induction of bacterial cell membrane damage, the results suggest that lavender essential oil may be a suitable alternative to conventional chemical-based anti-malodor agents.