Ag-Decorated Hydrogen Molybdenum Bronze Nanotubes as Dual-Action Agents Against Bacillus subtilis: Experimental and Theoretical Insights Into Membrane Damage and Protein Interference.

Bacterial biofilm is a tri-dimensional complex community of cells at different metabolic stages involved in a matrix of self-produced extracellular polymeric substances. Biofilm formation is part of a defense mechanism that allows the bacteria to survive in hostile environments, such as increasing resistance or tolerance to antimicrobial agents, causing persistent infections hard to treat and impair disease eradication. One such example is bovine mastitis associated with Streptococcus dysgalactiae subsp. dysgalactiae (SDSD), whose worldwide health and economic impact is on the surge. As such, non-conventional nanobased approaches have been proposed as an alternative to tackle biofilm formation and to which pathogenic bacteria fail to adapt. Among these, metallic nanoparticles have gained significant attention, particularly gold and silver nanoparticles, due to their ease of synthesis and impact against microorganism growth. This study provides a proof-of-concept investigation into the use of gold-silver alloy nanoparticles (AuAgNPs) toward eradication of bacterial biofilms. Upon visible light irradiation of AuAgNPs there was considerable disturbance of the biofilms’ matrix. The hindering of structural integrity of the biofilm matrix resulted in an increased permeability for entry of antibiotics, which then cause the eradication of biofilm and inhibit subsequent biofilm formation. Additionally, our results that AuAgNPs inhibited the formation of SDSD biofilms via distinct stress pathways that lead to the downregulation of two genes critical for biofilm production, namely, brpA-like encoding biofilm regulatory protein and fbpA fibronectin-binding protein A. This study provides useful information to assist the development of nanoparticle-based strategies for the active treatment of biofilm-related infections triggered by photoirradiation in the visible.

Synthesis, structural elucidation, and antibacterial activities of novel copper(II), cobalt(II), and nickel(II) complexes with a bidentate Schiff base ligand against pathogenic bacteria

Biofilm Formation on Clinically Noninfected Penile Prostheses

The Potential Role of N-Acetylcysteine for the Treatment of Helicobacter pylori

Biomimetic surfaces: Insights on the role of surface topography and wetting properties in bacterial attachment and biofilm formation

Biofilm formation is a crucial virulent attribute of pathogens that promotes their resistance to antibiotics and contributes to chronic illnesses in humans. Traditional antibiotic therapies have proven ineffective in eliminating sessile microbial populations within biofilms, necessitating the development of novel therapeutic strategies. In this study, the in vitro efficacy of the anti-biofilm enzymes derived from Bacillus subtilis was evaluated against biofilm-forming human clinical pathogens. An in vitro impact of combined anti-biofilm enzymes obtained from Bacillus subtilis C5W on the inhibition and eradication of biofilms of A. baumannii, E. aerogenes, and E.coli was monitored using a spectrophotometric microtiter plate assay. Among seven clinical pathogens, three pathogens were found to be strong biofilm producers as they formed biofilm at an incubation time of 48 hours. The anti-biofilm enzymes significantly inhibited the biofilm formation of A. baumannii and E. aerogenes at an incubation time of 48 hours, with inhibition rates of 62.51% and 57.91%, respectively. In contrast, the maximum inhibition of biofilm formation in E. coli was observed at 24 hours, with an inhibition rate of 76.69%. The biofilm eradication rates were recorded to be 30.17% (A. baumannii), 46.29% (E. aerogenes), and 53.02% (E. coli) after a 24-hour incubation time. The SEM images confirmed the disruption of adhered biofilm on the glass surface and aggregation of microcolonies. The study highlighted that Bacillus subtilis-derived enzyme combinations showed a synergistic inhibitory effect against biofilms formed by human clinical pathogens under in vitro conditions. The combined enzymatic treatment not only disrupted established biofilms but also suppressed their formation, indicating an enhanced anti-biofilm potential. These findings demonstrated the multi-enzyme approach as a promising and effective alternative to conventional antimicrobial approaches for managing biofilm-associated infections.

Foodborne illness caused by bacterial pathogens is a global health concern and results in millions of infections annually. Therefore, food products typically undergo several processing stages, including sanitation steps, before being distributed in an attempt to remove pathogens. However, many sanitation methods have compounding effects on the color, texture, flavor, and nutritional quality of the product or do not effectively reduce the pathogens that food can be exposed to. Some bacterial pathogens particularly possess traits and tactics that make them even more difficult to mitigate such as biofilm formation. Non-thermal plasma sanitation techniques, including plasma-treated water (PTW), have proven to be promising methods that significantly reduce pathogenic bacteria that food is exposed to. Published work reveals that PTW can effectively mitigate both gram-positive and gram-negative bacterial biofilms. This study presents a novel analysis of the differences in antimicrobial effects of PTW treatment between biofilm-forming gram-positive bacteria, commonly associated with foodborne illness, that are sporulating (Bacillus cereus) and non-sporulating (Listeria monocytogenes). After treatment with PTW, the results suggest the following hypotheses: (1) that the non-sporulating species experiences less membrane damage but a greater reduction in metabolic activity, leading to a possible viable but non-culturable (VBNC) state, and (2) that the sporulating species undergoes spore formation, which may subsequently convert into vegetative cells over time. PTW treatment on gram-positive bacterial biofilms that persist in food processing environments proves to be effective in reducing the proliferating abilities of the bacteria. However, the variance in PTW’s effects on metabolic activity and cell vitality between sporulating and non-sporulating species suggest that other survival tactics might be induced. This analysis further informs the application of PTW in food processing as an effective sanitation method.

Biofilm formation (BF) and production in the food processing industry (FPI) is a continual threat to food safety and quality. Various bacterial pathogens possess the ability to adhere and produce biofilms on stainless steel (SS) in the FPI due to flagella, curli, pili, fimbrial adhesins, extra polymeric substances, and surface proteins. The facilitating environmental conditions (temperature, pressure, variations in climatic conditions), SS properties (surface energy, hydrophobicity, surface roughness, topography), type of raw food materials, pre-processing, and processing conditions play a significant role in the enhancement of bacterial adhesion and favorable condition for BF. Furthermore, biofilm formers can tolerate different sanitizers and cleaning agents due to the constituents, concentration, contact time, bacterial cluster distribution, and composition of bacteria within the biofilm. Also, bacterial biofilms' ability to produce various endotoxins and exotoxins when consumed cause food infections and intoxications with serious health implications. It is thus crucial to understand BF's repercussions and develop effective interventions against these phenomena that make persistent pathogens difficult to remove in the food processing environment.

BackgroundIn this work, we represent synthesis, in silico analysis and biological activity of 1,4 diazepine linked piperidine derivatives (6a–6o). All the derivatives were screened for their anti-microbial activity against gram-positive (Staphylococcus aureus, Bacillus Subtills, Bacillus megaterium) and gram-negative (Escherichia coli, Pseudonymous, Shigella sp.) bacteria. Compounds were synthesized from reaction of tert-butyl 1,4-diazepane-1-carboxylic, butyryl chloride and varied aromatic aldehyde, further characterized by 1H NMR and LCMS spectral techniques.ResultUsing ampicillin as a positive control, the synthetic compounds 6a–6o were tested for their in-silico study and experimental anti-microbial activity against gram-positive (Staphylococcus aureus, Bacillus Subtills, Bacillus megaterium) and gram-negative (Escherichia coli, Pseudonymous, Shigella sp.) bacteria. According to in vitro assay compound 6a, compound 6c, compound 6d, compound 6m and compound 6I showed higher activity against all the tested strains. Molecule 6i, compound 6j, compound 6k, compound 6f has good to moderate antibacterial activity. DFT computations were used to optimize the molecular geometry at the B3LYP/6-31G (d, p) theoretical level. The corresponding energy values of molecular orbitals were visualized using optimized geometries. Moreover, Auto Dock Vina 1.2.0 is used to assess molecular docking against two target proteins, Bacillus subtilis (PDB ID: 6UF6) and Protease Vulgaris (PDB ID: 5HXW). The target molecule 6b displayed the best binding energies for both. Additionally, we calculated the ADME for each molecule (6a–6o).ConclusionAll fifteen synthesized compounds were screened for their in vitro and in silico analysis. In vitro analysis for anti-microbial activity was carried out against gram-positive (Staphylococcus aureus, Bacillus Subtills, Bacillus megaterium) and gram-negative (Escherichia coli, Pseudonymous, Shigella sp.) bacteria and compound 6a, compound 6c, compound 6d, compound 6m and compound 6I exhibits more potent activity towards all tested strains. Molecular docking is performed against target proteins, L-amino acid deaminase from Proteus Vulgaris and LcpA ligase from Bacillus subtilis, representing the Gram-negative bacterium and Gram-positive bacterium, respectively. Compound 6b showed the highest no. of interaction with protein according to molecular docking. With the advent of innovative techniques like ADME, we select their hit compounds early on and anticipate future pharmacokinetic and pharmacodynamic benefits and drawbacks of these promising therapeutic candidates.Graphical abstract

Emergence of new resistant strains of microorganisms to current antibiotics has become a major issue in public health; therefore, it is imperative to develop new bactericides. This study, thus, aimed at synthesizing silver nanoparticle (AgNP) and determining their antibacterial activities on bacterial biofilms. Sachet water and well water samples were collected from sachet water industries and two hand-dung wells around Gbonagun piggery house, respectively from where isolation and identification of microorganisms was carried out using standard techniques. Identified bacterial isolates were screened for biofilm formation using tube test as well as congo red method and the fungi isolate was used to synthesize AgNP. The formation of silver nanoparticles was confirmed by the physical change of colour and absorption peak between 250-800 nm was evaluated using UV-Vis spectroscopy. Further, the synthesized AgNPs were characterized by Fourier transform infrared spectroscopy. Antibacterial activities of the silver nanoparticles on the biofilms formers was investigated using agar well diffusion method and the potential to prevent the growth of biofilms was evaluated. Predominant bacterium and fungi are Bacillus subtilis and Aspergillus species. Biofilm formers as revealed by the tube test and congo red method are: B. subtilis, Enterobacter cloacae, Proteus mirabilis, Klebsiella pneumonia, Streptococcus pyogenes and Staphylococcus aureus. The color of the synthesized silver nanoparticles by A.niger was yellowish brown and control showed no colour change. The UV-visible spectra of the nanoparticles exhibited an absorbance peak (band) at approximately 425 nm. The FTIR analysis revealed the presence of coordinating NH2, OH, amides I and II among others, ligating functional groups in the biomass of A. niger responsible for efficient capping and stabilizing of the AgNPs. Synthesized AgNPs prevented the growth of biofilm formers by exhibiting highest zone of inhibition of 18.5mm. The ability of the synthesized silver nanoparticles to inhibit growth of bacterial biofilms by Bacillus subtilis present the mould (A. niger) as bio resource with good bactericidal activities.

Antibiotic-resistant microbes are a global threat, necessitating the need for new antibacterials. Bioactive compounds obtained from Asparagus racemosus and silver nanoparticles synthesized from it were tested for antibacterial activity. The nanoparticles exhibited a UV absorbance peak at 415nm. SEM image revealed elliptical nanoparticles from 32.6 nm to 78.6 nm while the FTIR study of aromatic amine N-H and C-O stretching indicates the stability of the silver nanoparticle. Zeta potential and XRD tests confirmed the presence of silver nanoparticles in the root extract under stable conditions. Methanolic root extract and silver nanoparticles were found to be very effective against Bacillus subtilis (20mm), Salmonella typhimurium (20mm), Escherichia coli (20mm), Klebsiella pneumoniae (18mm), Staphylococcus aureus (17mm) and Pseudomonas aeruginosa (15mm) in comparison to ampicillin. AutoDock Tools 1.5.7 was used to perform molecular docking of Shatavarin IV against target proteins involved in breast cancer (PDB ID: 3O96), bacterial infections (PDB ID: 2ZCO), viral infections angiotensin (PDB ID: 4APH) and inflammation (PDB ID: 7PHS). The respective best docking scores are -18.66, -18.07 -14.57 and -15.84 Kcal/Mol respectively. Sarsasapogenin and Kaempferol also showed favorable docking scores with specific target proteins. Shatavarin IV is found to target amino acid(s) and the standard drugs of each category such as Remdesivir for viral, Diclofenac for inflammation, Tamoxifen for cancer and Plazomicin for bacterial infections. This study reveals that Asparagus racemosus bioactive compound Shatavarin IV is a suitable lead compound for the treatment of cancer, viral, bacterial infections and inflammatory conditions.

Experimental and theoretical corroboration of antimicrobial and anticancer activities of two pseudohalides induced structurally diverse Cd (II)-Salen complexes

Bacterial biofilms are difficult to eradicate from surfaces using conventional antimicrobial interventions. High-throughput 96-well microplate methods are frequently used to cultivate bacterial biofilms for rapid antimicrobial susceptibility testing to calculate minimal biofilm eradication concentration (MBEC) values. Standard biofilm devices consist of polystyrene pegged-lids fitted to 96-well microplates and are ideal for measuring biofilm biomass and MBEC values, but these devices are limited by available peg surface area for biomass accumulation and cost. Here, we outline a protocol to use self-assembled polypropylene 96-well deep well PCR-plate pegged-lid device to grow Escherichia coli BW25113 and Pseudomonas aeruginosa PAO1 biofilms. A comparison of 24-hour biofilms formed on standard and deep well devices by each species using crystal violet biomass staining and MBEC determination assays are described. The larger surface area of deep well devices expectedly increased overall biofilm formation by both species 2-4-fold. P. aeruginosa formed significantly greater biomass/mm2 on deep well pegs as compared to the standard device. E. coli had greater biomass/mm2 on standard polystyrene devices as compared the deep well device. Biofilm eradication assays with disinfectants such as sodium hypochlorite (bleach) or benzalkonium chloride (BZK) showed that both compounds could eliminate E. coli and P. aeruginosa biofilms from both devices but at different MBEC values. BZK biofilm eradication resulted in variable E. coli MBEC values between devices, however, bleach demonstrated reproducible MBEC values for both species and devices. This study provides a high throughput deep well method for growing larger quantities of biofilms on polypropylene devices for downstream studies requiring higher amounts of static biofilm.

Structural Characterization of the Multidomain Regulatory Protein Rv1364c from Mycobacterium tuberculosis

Biofilms are structured communities of cells that are encased in a self-produced polymeric matrix and are adherent to a surface. Many biofilms have a significant impact in medical and industrial settings. The model gram-positive bacterium Bacillus subtilis has recently been shown to form biofilms. To gain insight into the genes involved in biofilm formation by this bacterium, we used DNA microarrays representing >99% of the annotated B. subtilis open reading frames to follow the temporal changes in gene expression that occurred as cells transitioned from a planktonic to a biofilm state. We identified 519 genes that were differentially expressed at one or more time points as cells transitioned to a biofilm. Approximately 6% of the genes of B. subtilis were differentially expressed at a time when 98% of the cells in the population were in a biofilm. These genes were involved in motility, phage-related functions, and metabolism. By comparing the genes differentially expressed during biofilm formation with those identified in other genomewide transcriptional-profiling studies, we were able to identify several transcription factors whose activities appeared to be altered during the transition from a planktonic state to a biofilm. Two of these transcription factors were Spo0A and sigma-H, which had previously been shown to affect biofilm formation by B. subtilis. A third signal that appeared to be affecting gene expression during biofilm formation was glucose depletion. Through quantitative biofilm assays and confocal scanning laser microscopy, we observed that glucose inhibited biofilm formation through the catabolite control protein CcpA.