Biofilm Formation Research Articles

Moroccan Hospital Cockroaches: Carriers of Multidrug-Resistant Gram-Negative Bacteria.

Antimicrobial resistance in Gram-negative bacteria (GNB) is a growing global health concern, particularly in hospital environments, where cockroaches act as vectors for resistant strains. This study aimed to analyze antimicrobial resistance and biofilm formation in GNB isolated from cockroaches collected in the hospital environment. Cockroaches were collected, and bacterial isolation was performed from their gut contents and external surfaces. GNB strains were tested for antibiotic susceptibility using the disk diffusion method and examined for Extended-spectrum β-lactamases (ESBLs) and carbapenemases production. Molecular characterization of ESBLs and carbapenemases in GNB involved PCR amplification of antibiotic resistance genes, while biofilm formation was studied using a microplate assay. Seventy-five cockroaches were collected from which 165 GNB were isolated. The prevalence of ESBL-producing and carbapenemase-producing GNB was 6.7 and 1.8%, respectively. The predominant ESBL gene was blaCTX-M-28, while blaNDM-1 was the only carbapenemase gene detected. The qnrS1 gene was found in one NDM-1-producing Klebsiella pneumoniae and three ESBL-producing Escherichia coli. The qacΔE1 gene was detected in an NDM-1-producing Citrobacter freundii and a CTX-M-28-producing E. coli, whereas one NDM-1-producing Enterobacter cloacae carried both qacΔE1 and acrA genes. Strains harboring qacΔE1 and/or acrA genes exhibited biofilm-forming capabilities, with biofilm formation observed in 81.81% of ESBL-producing isolates and 100% of carbapenemase-producing isolates. The study underscores the role of cockroaches in carrying and disseminating ESBL- and carbapenemase-producing GNB in hospital settings. The coexistence of disinfectant resistance genes and antibiotic resistance suggests co-selection mechanisms, while biofilm formation enhances bacterial survival. These findings underline the urgent need for infection control strategies.

Disrupting quorum sensing by exploring conformational dynamics and active site flexibility of LasR protein in Pseudomonas aeruginosa

Quorum sensing in Pseudomonas aeruginosa, regulated by the LasR protein, controls bacterial virulence and biofilm formation. Targeting this system offers a promising strategy to combat infections. This study investigates the binding and conformational dynamics of LasR with its native ligand, N-3-oxo-dodecanoyl-L-homoserine lactone (AHL), and a natural product compound, ClaO, using molecular docking, molecular dynamics simulations, and binding free energy calculations. Docking validation confirmed AHL’s accurate re-docking (binding energy: − 8.3 kcal/mol, RMSD: 1.199 Å). ClaO exhibited a stronger binding affinity (− 8.9 kcal/mol), suggesting favorable interactions with LasR. Both ligands formed key hydrophobic and hydrophilic contacts with residues such as TRP60, TYR93, SER129, and ASP73. Molecular dynamics simulations revealed that AHL stabilized the LasR structure, while ClaO induced increased flexibility, indicating different binding mechanisms. Binding free energy analysis showed that ClaO had stronger van der Waals (− 187.6 kJ/mol) and electrostatic interactions (− 139.4 kJ/mol) than AHL (− 182.9 kJ/mol, − 131.8 kJ/mol). However, ClaO’s higher polar desolvation energy (287.2 kJ/mol) reduced its binding efficiency. AHL had a slightly more favorable binding free energy (− 76.3 kJ/mol) compared to ClaO (− 72.6 kJ/mol), suggesting a more stable interaction. These findings highlight the differential effects of AHL and ClaO on LasR stability and flexibility. While ClaO engages in stronger interactions, its desolvation penalty offsets its binding advantage. This study provides molecular insights into quorum sensing inhibition and supports the development of novel LasR-targeting therapeutics. Clinical trial number: Not applicable.Graphical

Antimicrobial Mechanisms of Hibiscus sabdariffa Extracts and Hibiscus Acid Against Campylobacter jejuni: Membrane Disruption, Biofilm Modulation, and Antibiotic Resistance Implications

ABSTRACTThe objective was to evaluate the antimicrobial effects and possible mechanisms of action of extracts of Hibiscus sabdariffa calyxes and hibiscus acid (AH) on Campylobacter jejuni. The antimicrobial effect of extracts of H. sabdariffa calyxes (obtained with water, acetone, methanol, and ethanol) was evaluated alone and in a mixture with antibiotics using the paper disk technique. Possible damage to the membrane through permeability modification, leakage of genetic material and proteins, modification of zeta potential (ζ), electrophoretic mobility, pore formation, and the effect on biofilm formation was also investigated. The study found that extracts from H. sabdariffa calyxes, particularly the acetone extract (AE) and AH, effectively inhibited C. jejuni by damaging its membrane, causing leakage of genetic material and proteins, and altering zeta potential (ζ) and electrophoretic mobility. Both AE and AH also disrupted biofilm formation and induced membrane porosity. However, no synergistic effect was observed when combined with antibiotics. The findings suggest that these extracts could be potential alternatives to antibiotics for combating antibiotic‐resistant C. jejuni.

Aspergillus fumigatus secondary metabolite pyripyropene is important for the dual biofilm formation with Pseudomonas aeruginosa.

The human pathogenic fungus Aspergillus fumigatus establishes dual biofilm interactions in the lungs with the pathogenic bacterium Pseudomonas aeruginosa. Screening of 21 A. fumigatus null mutants revealed seven mutants (two G protein-coupled receptors, three mitogen-activated protein kinase receptors, a Gα protein, and one histidine kinase receptor) with reduced biofilm formation, specifically in the presence of P. aeruginosa. Transcriptional profiling and metabolomics analysis of secondary metabolites produced by one of these mutants, ΔgpaB (gpaB encodes a Gα protein), showed GpaB controls the production of several important metabolites for the dual biofilm interaction, including pyripyropene A, a potent inhibitor of mammalian acyl-CoA cholesterol acyltransferase. Deletion of pyr2, encoding a non-reducing polyketide synthase essential for pyripyropene biosynthesis, showed reduced A. fumigatus Δpyr2-P. aeruginosa biofilm growth, altered macrophage responses, and attenuated mouse virulence in a chemotherapeutic murine model. We identified pyripyropene as a novel player in the ecology and pathogenic interactions of this important human fungal pathogen.IMPORTANCEAspergillus fumigatus and Pseudomonas aeruginosa are two important human pathogens. Both organisms establish biofilm interactions in patients affected with chronic lung pulmonary infections, such as cystic fibrosis (CF) and chronic obstructive pulmonary disease. Colonization with A. fumigatus is associated with an increased risk of P. aeruginosa colonization in CF patients, and disease prognosis is poor when both pathogens are present. Here, we identified A. fumigatus genetic determinants important for the establishment of in vitro dual A. fumigatus-P. aeruginosa biofilm interactions. Among them, an A. fumigatus Gα protein GpaB is important for this interaction controlling the production of the secondary metabolite pyripyropene. We demonstrate that the lack of pyripyropene production decreases the dual biofilm interaction between the two species as well as the virulence of A. fumigatus in a chemotherapeutic murine model of aspergillosis. These results reveal a complete novel role for this secondary metabolite in the ecology and pathogenic interactions of this important human fungal pathogen.

Study on molecular characteristics of Staphylococcus from yak milk-Xizang

This study investigated the biological characteristics of Staphylococcus strains isolated from Xizangan yak milk by examining the antibiotic resistance phenotypes of 69 isolates against 18 antibiotics, detecting 31 associated resistance genes, identifying 16 virulence genes, and assessing biofilm formation capability. Furthermore, molecular typing techniques including spa typing, multilocus sequence typing (MLST), and Staphylococcus cassette chromosome mec (SCCmec) were used for detailed characterization of the isolates. The findings revealed a high penicillin resistance rate of 72.46%. Resistance genes such as gyrA (100.00%), glrB (92.75%), and gyrB (44.93%) were prevalent. The detection rates were 81.16% and 55.07% for the beta-lactamase gene blaZ and the mecA gene, respectively. Among the tested virulence genes, lukS, lukF, hla, clfA, and icaD were detected in 40.58% of isolates, while sec was detected in 24.64%. MLST typing identified four isolates belonging to the ST62623 type and 24 other isolates representing novel ST types not reported on PubMLST.org. Spa typing revealed spa types t1940 (n = 9), t3022 (n = 8), t4558 (n = 6), t4236 (n = 3), t4445 (n = 1), and one unreported spa type. For SCCmec typing, 11 isolates were typed as SCCmec IVb and 9 as SCCmec V. These findings significantly enhance our understanding of the biological characteristics of Staphylococcus strains derived from Xizangan yak milk.

A genomic and phenotypic investigation of pigeon-adaptive Salmonella.

Salmonella, a significant threat to public safety, inflicts substantial economic losses on the poultry industry. The unique "parental feeding" breeding model of pigeon farms, against the "all-in & all-out" biosecurity strategy, makes them susceptible to Salmonella infections and subsequent outbreaks of pigeon paratyphoid. This study initially studied three pigeon paratyphoid outbreak incidents in Henan, China, in which 53 strains of pigeon-origin Salmonella Typhimurium (STM) were identified. Whole-genome sequencing (WGS) and antimicrobial-resistant profile analysis revealed that the three outbreaks were caused by distinct STM clones (ST128-DT2, ST19-DT99). Global phylogenetic analysis suggested that the United States is a possible origin, indicating a risk of intercontinental transmission via pigeon eggs. Further bacterial virulence and invasion assays, including in vitro and in vivo assays, revealed that pigeon-host-adaptive STM, compared to broad-host-range STM, carried fewer resistance genes, exhibited higher invasion indices and pseudogene levels, displayed a non-rdar (red dry and rough) phenotype, and had strong biofilm formation capability. Additionally, they showed reduced virulence and invasiveness in mice but a pigeon-adaptive feature in cogent models. The collective results support the host adaptation for pigeons among DT2 and DT99 phage-type isolates.

Insights into biofilm-mediated mechanisms driving last-resort antibiotic resistance in clinical ESKAPE pathogens.

The rise of antibiotic-resistant bacteria poses a grave threat to global health, with the ESKAPE pathogens, which comprise Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp. being among the most notorious. The World Health Organization has reserved a group of last-resort antibiotics for treating multidrug-resistant bacterial infections, including those caused by ESKAPE pathogens. This situation calls for a comprehensive understanding of the resistance mechanisms as it threatens public health and hinder progress toward the Sustainable Development Goal (SDG) 3: Good Health and Well-being. The present article reviews resistance mechanisms, focusing on emerging resistance mutations in multidrug-resistant ESKAPE pathogens, particularly against last-resort antibiotics, and describes the role of biofilm formation in multidrug-resistant ESKAPE pathogens. It discusses the latest therapeutic advances, including the use of antimicrobial peptides and CRISPR-Cas systems, and the modulation of quorum sensing and iron homeostasis, which offer promising strategies for countering resistance. The integration of CRISPR-based tools and biofilm-targeted approaches provides a potential framework for managing ESKAPE infections. By highlighting the spread of current resistance mutations and biofilm-targeted approaches, the review aims to contribute significantly to advancing our understanding and strategies in combatting this pressing global health challenge.

Characterization of AI-2/LuxS quorum sensing system in antibiotic resistance, pathogenicity of non carbapenemase-producing carbapenem-resistant Escherichia coli

BackgroundAs a quorum sensing system, LuxS/AI-2 is closely associated with bacterial growth, biofilm formation, and virulence. As yet, it is not known how the luxS is associated with a diverse array of physiological activities in non- carbapenemase producing carbapenem resistant Escherichia coli (non-CP-CREC). The purpose of this study is to explore the characterization of AI-2/LuxS quorum sensing system in antibiotic resistance, pathogenicity of non-CP-CREC.MethodsA total of five non-CP-CREC isolates that did not have ompC and ompF deletions were collected from various clinical samples from January 2021 to December 2023. RT-qPCR was used to detect genes expression of luxS, acrA, acrB, tolC, mdtB, mdtC, mdtE, mdtF, ompA, ompX, IL-8, IL-6, and TNF-α. Homologous recombination was used to create the luxS knockout strain. Transcriptome sequencing was utilized to analyze gene expression changes before and after the luxS knockout. Biofilm formation was detected using crystal violet staining. Antimicrobial susceptibility test was used to determine drug resistance. Bacterial growth curves were used to detect the influence of the luxS on bacterial growth. A cell infection assay was used to detect the impact of the luxS on bacterial adhesion and the inflammatory response it induces.ResultsOur results indicated that the expression of the luxS was significantly elevated in non-CP-CREC strains compared to the carbapenem antibiotics sensitive E. coli (CSEC), with CREC229 exhibiting the most pronounced difference. Consequently, CREC229 was chosen for the development of the luxS knockout strain (CREC229△luxS). The deletion of the luxS did not impact the growth of non-CP-CREC. RNA sequencing analysis revealed that 82 genes were differentially expressed, with notable alterations observed in genes associated with biofilm formation regulation and outer membrane proteins in the ΔluxS strain. Our transcriptomic results show that the expression of bssS associated with biofilm formation is significantly reduced in the ΔluxS strain, which in turn reduces its capacity for biofilm formation. In addition, the luxS deletion increased the expression of adhesion-related genes, such as ompA and ompX, enhanced HCT-8 adherence to CREC229, and promoted the secretion of the inflammatory cytokine IL-6. In terms of bacterial resistance, the deletion of luxS increased the sensitivity of non-CP-CRECs to aminoglycoside antibiotics.ConclusionsLuxS/AI-2 quorum sensing systems can alter pathogenicity and resistance in several ways.

Protective effect of histatin 5 and amphotericin B conjugated nanostructures in C. albicans challenged Swiss albino mice.

This study explores the development of silica-gold nanostructures conjugated with histatin 5 (H5) and amphotericin B (AmpB) for the management of Candida albicans-induced candidiasis. H5 and AmpB were covalently attached to the silica-gold nanostructures (ASinp-GN) using EDC-NHS chemistry, with fluorescent FITC labeling employed in a parallel experiment to study nanostructure localization. Characterization techniques, including UV-Vis spectroscopy, dynamic light scattering, zeta potential analysis, fluorescence spectroscopy, differential scanning calorimetry, thermogravimetric analysis, high-resolution transmission electron microscopy, atomic force microscopy, and drug release studies, confirmed the successful conjugation and stability of the nanostructures. Biological evaluations using C. albicans demonstrated a minimum inhibitory concentration (MIC50) of 5.42μM for AmpB in the nanostructures, along with enhanced localization as observed via fluorescence microscopy. The nanostructures effectively inhibited biofilm formation and showed high biocompatibility in hemolysis and MTT assays. In vivo studies using a disseminated candidiasis model in Swiss albino mice revealed significant therapeutic efficacy, evidenced by reduced C. albicans burden, decreased AmpB toxicity, improved heart function, and preserved tissue integrity. These results highlight the role of H5 conjugation in targeted drug delivery, enhancing the therapeutic potential of AmpB while minimizing adverse effects, making it a promising approach for candidiasis management. However, a detailed pharmacokinetic investigation on the use of these nanostructures is warranted before taking this to the clinical side.

Prevalence, antibiotic resistance, and biofilm formation of coagulase-positive staphylococci in Izmir Tulum Cheese

Coagulase-positive staphylococci (CPS) are the main causative bacterial agents of staphylococcal food intoxication, posing a significant public health risk and causing infections in humans and animals. In this study, a hundred Izmir Tulum Cheese samples were collected from various retail outlets in the Izmir province. CPS isolates from cheese samples were identified using standard cultural methods. The phenotypic antibiotic resistance of CPS isolates was determined using the agar disk diffusion test method, while their biofilm formation capacity was assessed using the colorimetric method. In the study, CPS was isolated from 30 out of 100 analyzed Izmir Tulum Cheese samples (30%), and it was determined that 27 of these samples (27%) had CPS levels exceeding the maximum acceptable limit of 10³ CFU/g set by the Turkish Food Codex Microbiological Criteria Regulation. Antimicrobial resistance analysis revealed that among the 30 CPS isolates, 90% were resistant to penicillin, while resistance rates to other commonly used antibiotics were 83.3% for clindamycin, 56.7% for ciprofloxacin, and 53.3% for tetracycline. Additionally, 76.7% of the isolates were multidrug-resistant, meaning they were not easily killed by different antibiotics, which limits treatment options. Furthermore, 83.3% of the CPS isolates had the capacity for biofilm formation, highlighting its impact on food safety. These findings emphasize the need for stricter hygiene protocols, controlled antibiotic use, and innovative strategies to combat biofilms in dairy production.

Functional and Pangenomic Exploration of Roc Two-Component Regulatory Systems Identifies Novel Players Across Pseudomonas Species.

The opportunistic pathogen Pseudomonas aeruginosa relies on a large collection of two-component regulatory systems (TCSs) to sense and adapt to changing environments. Among them, the Roc (regulation of cup) system is a one-of-a-kind network of branched TCSs, composed of two histidine kinases (HKs-RocS1 and RocS2) interacting with three response regulators (RRs-RocA1, RocR, and RocA2), which regulate virulence, antibiotic resistance, and biofilm formation. Based on extensive work on the Roc system, previous data suggested the existence of other key regulators yet to be discovered. In this work, we identified PA4080, renamed RocA3, as a fourth RR that is activated by RocS1 and RocS2 and that positively controls the expression of the cupB operon. Comparative genomic analysis of the locus identified a gene-rocR3-adjacent to rocA3 in a subpopulation of strains that encodes a protein with structural and functional similarity to the c-di-GMP phosphodiesterase RocR. Furthermore, we identified a fourth branch of the Roc system consisting of the PA2583 HK, renamed RocS4, and the Hpt protein HptA. Using a bacterial two-hybrid system, we showed that RocS4 interacts with HptA, which in turn interacts with RocA1, RocA2, and RocR3. Finally, we mapped the pangenomic RRs repertoire, establishing a comprehensive view of the plasticity of such regulators among clades of the species. Overall, our work provides a comprehensive inter-species definition of the Roc system, nearly doubling the number of proteins known to be involved in this interconnected network of TCSs controlling pathogenicity in Pseudomonas species.

Valdiazen Derivatives for Chemoproteomic Studies in Burkholderia cenocepacia H111.

Quorum sensing allows bacteria to coordinate community-wide behaviours such as biofilm formation, virulence, and symbiosis. The diazeniumdiolate valdiazen has been identified in the opportunistic pathogen Burkholderia cenocepacia H111 as a novel quorum-sensing signal, yet its protein interactome has remained unexplored. In this study, we employed a chemoproteomic pulldown approach to identify potential valdiazen-binding proteins. For these pulldown experiments, a series of alkyne-linked and biotin-conjugated valdiazen probes were synthesised. Affinity-based pulldown experiments using biotin-valdiazen conjugates successfully identified several putative proteins including an ATP synthase subunit, a succinylglutamate desuccinylase/aspartoacylase, a granule-associated protein, an acetyl-CoA hydrolase, a serine protease and an OmpA/MotB precursor. Overall, this study provides insights into the valdiazen-protein interactome in Burkholderia cenocepacia H111, advancing our understanding of the role of valdiazen in bacterial quorum sensing.

Combination therapy delays antimicrobial resistance after adaptive laboratory evolution of Staphylococcus aureus.

Antibiotic resistance, driven by misuse and overuse of antibiotics, is one of the greatest threats against human health. The antimicrobial pressure during prolonged antibiotic treatment of chronic bacterial infections selects for resistance. While antibiotic combinations may reduce resistance emergence, antibiotic-tolerant persister cells can serve as a reservoir for resistance development. Therefore, targeting these cells with anti-persister drugs might provide a novel strategy for resistance prevention. In this study, we conducted 42 days of adaptive laboratory evolution using Staphylococcus aureus exposed to rifampicin, ciprofloxacin, daptomycin, and vancomycin, alone or in combination with the anti-persister drug mitomycin C. We monitored antibiotic susceptibility daily and assessed phenotypic changes in growth and biofilm formation in evolved strains. Whole-genome sequencing revealed mutations linked to antibiotic resistance and phenotypic shifts. Rifampicin resistance developed within a few days, while ciprofloxacin and daptomycin emerged in approximately 3 weeks. Treatments with vancomycin or mitomycin C resulted in minimal changes in susceptibility. While combination therapy delayed resistance, it did not fully prevent it. Notably, the combination of rifampicin with mitomycin C maintained rifampicin susceptibility throughout the long-term evolution experiment. Sub-inhibitory antibiotic treatments selected for both previously characterized and novel mutations, including unprecedented alterations in the nucleotide excision repair system and azoreductase following mitomycin C exposure. The delayed resistance development observed with combination therapy, particularly mitomycin C's ability to suppress rifampicin resistance, suggests potential therapeutic applications. Future studies should evaluate the clinical efficacy of anti-persister drugs in preventing resistance across different bacterial pathogens and infection models.

Artificial Bone Materials for Infected Bone Defects: Advances in Antimicrobial Functions.

Infected bone defects, caused by bacterial contamination following disease or injury, result in the partial loss or destruction of bone tissue. Traditional bone transplantation and other clinical approaches often fail to address the therapeutic complexities of these conditions effectively. In recent years, advanced biomaterials have attracted significant attention for their potential to enhance treatment outcomes. This review explores the pathogenic mechanisms underlying infected bone defects, including biofilm formation and bacterial internalization into bone cells, which allow bacteria to evade the host immune system. To control bacterial infection and facilitate bone repair, we focus on antibacterial materials for bone regeneration. A detailed introduction is given on intrinsically antibacterial materials (e.g., metal alloys, oxide materials, carbon-based materials, hydroxyapatite, chitosan, and Sericin). The antibacterial functionality of bone repair materials can be enhanced through strategies such as the incorporation of antimicrobial ions, surface modification, and the combined use of multiple materials to treat infected bone defects. Key innovations discussed include biomaterials that release therapeutic agents, functional contact biomaterials, and bioresponsive materials, which collectively enhance antibacterial efficacy. Research on the clinical translation of antimicrobial bone materials has also facilitated their practical application in infection prevention and bone healing. In conclusion, advancements in biomaterials provide promising pathways for developing more biocompatible, effective, and personalized therapies to reconstruct infected bone defects.

RpoN1 (sigma factor 54) contributes to the virulence of Paracidovorax citrulli by regulating the expression of type IV pili PilA

The σ54 factor (RpoN), a significant transcriptional regulatory factor, plays crucial roles in regulating virulence, motility, biofilm formation, and the utilization of carbon and nitrogen sources in pathogenic bacteria. However, the function of RpoN has not been identified in Paracidovorax citrulli (formerly Acidovorax citrulli). To investigate this, we constructed a rpoN1 deletion mutant and a corresponding complement strain in the background of P. citrulli strain xjl12. The P. citrulli rpoN1 deletion mutant displayed attenuated virulence in melon. RNA-Seq analysis revealed that rpoN1 is involved in regulating the expression of certain pathogenicity-associated genes related to the secretion system, biofilm formation, and motility. Phenotypic analysis demonstrated that the rpoN1 deletion mutant of P. citrulli significantly attenuated biofilm formation, twitch motility, swarming motility, cotyledon colonization, and seed colonization. However, swimming motility was significantly enhanced in the rpoN1 mutant. As expected, qRT-PCR assays indicated that the type IV pili-related gene Aave_4679 (pilA) was barely expressed in the rpoN1 mutant, and western blot analysis revealed that RpoN1 positively regulated the expression of pilA. Additionally, bacterial one-hybrid assays and electrophoretic mobility shift assays indicated that RpoN1 directly binds to the promoter of pilA. Our investigation revealed that RpoN1 is essential for the virulence of P. citrulli and provides valuable insights into the physiology and pathogenic mechanisms of bacterial fruit blotch.

Nanoscale Surface Modifications on Titanium Plates- A Strategy to Mitigate MRSA Biofilm-mediated Implant Infections: a pilot Study.

Nanoscale Surface Modifications on Titanium Plates- A Strategy to Mitigate MRSA Biofilm-mediated Implant Infections: a pilot Study.

Draft genome sequence of benzo[a]pyrene degrading Bacillus altitudinis strain AR19 isolated from Digboi oil refinery (India).

Bacillus altitudinis AR19, isolated from the Digboi oil refinery (India), has a genome size of 3,630,000 bp with a G+C content of 42.45%. The genome encodes 3,755 protein-coding genes, including those for ring-cleaving dioxygenases and biofilm formation. These genes likely play crucial roles in the bacterium's survival in hydrocarbon-enriched environments.

Insights into the interfacial dynamics and interaction mechanisms between phosphate-solubilizing bacteria and straw-derived biochar

To alleviate soil phosphorus deficiency, integrating straw-derived biochar with phosphate-solubilizing bacteria (PSB) has been recognized as a promising solution and is gaining growing attention. However, the mechanisms of bacterial immobilization and the influences of the physicochemical attributes of biochar remain unclear. In this study, we investigated the single-cell interactions of gram-negative Acinetobacter pittii and gram-positive Bacillus subtilis with cotton straw-derived biochars, subjected to progressively increasing pyrolysis temperatures, to understand the attributes of gradually modified biochar properties. The results revealed the correlations between adhesion forces and biochar properties (e.g., surface area and surface charge), and the strongest adhesion for both strains for the biochar pyrolyzed at 700 °C. The extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) model, structured to predict interaction energy, was subsequently compared with experimental observations made using atomic force microscopy (AFM). Discrepancies between the predicted high adhesion barriers and the observed attraction suggested that forces beyond Lifshitz-van der Waals also influenced the immobilization of PSB. Adhesion-distance spectroscopy and XDLVO theory jointly revealed four distinct phases in the immobilization process by biochar: planktonic interaction, secondary minimum entrapment, primary barrier transcendence, and initial reversible adherence, collectively facilitating biofilm formation. Notably, initial reversible adhesion positively correlated with increased protein and polysaccharide levels in extracellular polymeric substances (EPS) (R2 > 0.67), highlighting its importance in biofilm formation. Unraveling PSB–biochar interactions can improve the effectiveness of soil inoculants, thereby enhancing phosphorus availability in soil, a crucial factor for promoting plant growth and supporting environmental sustainability.Graphical

Hybrid Molecules of Benzothiazole and Hydroxamic Acid as Dual-Acting Biofilm Inhibitors with Antibacterial Synergistic Effect against Pseudomonas aeruginosa Infections.

The ubiquitous opportunistic pathogen Pseudomonas aeruginosa (P. aeruginosa) causes biofilm-associated drug-resistant infections that often lead to treatment failure. Targeting the bacterium's quorum sensing (QS) and iron homeostasis presents a promising strategy to combat biofilm formation. This study synthesized benzothiazole-conjugated hydroxamic acid derivatives as dual-acting biofilm inhibitors, and compound JH21 was identified as the hit compound with potent submicromolar biofilm inhibitory activity (IC50 = 0.4 μM). Further mechanistic studies demonstrated not only that the production of virulence was decreased through mainly inhibiting QS system but also that JH21 competed for iron with the high-affinity siderophore pyoverdine, inducing iron deficiency and inhibiting biofilm. Moreover, JH21 significantly enhanced the efficacy of tobramycin and ciprofloxacin by 200- and 1000-fold, respectively, in a mouse wound infection model. These results emphasized the feasibility of dual-acting biofilm inhibitors against resistant P. aeruginosa infections and the potential of JH21 as a novel antibacterial synergist.

Antibiotic resistance and biofilm formation of thermoduric Kocuria and Micrococci isolated from the milk samples of healthy cows

Antibiotic resistance and biofilm formation of thermoduric Kocuria and Micrococci isolated from the milk samples of healthy cows