Collective condensation and auto-aggregation of Escherichia coli in uniform acidic environments.

Chemotaxis-the movement of cells along chemical gradients-leads to collective behaviors when cells coordinate their movements. Here, using Escherichia coli as a model, we demonstrate a distinct type of bacterial collective response in acidic environments containing organic acids. Bacterial populations immersed in such environments collectively condensed into millimeter-sized focal points. Furthermore, this bacterial condensation fostered the formation of small, tightly packed cell aggregates, resembling non-surface-attached biofilms. These cell aggregates were physically displaced by the free-swimming condensing cells, leading to the segregation of the two cell populations. Bacterial condensation relied on feedback between the tendency of these bacteria to neutralize the pH and their chemotactic repulsion from low pH. Sustained cell condensation occurred when the bacteria occupied only part of the acidic environment, either dynamically or due to physical constraints. Such condensed bacterial populations can mitigate acid stress more efficiently, a principle that may be applicable to other stress conditions.

Biofilm formation of Staphylococcus aureus on various implants used for surgical treatment of destructive spondylodiscitis.

The incidence of spondylodiscitis has witnessed a significant increase in recent decades. Surgical intervention becomes necessary in case of bone destruction to remove infected tissue and restore spinal stability, often involving the implantation of a cage. Despite appropriate treatment, relapses occur in up to 20 percent of cases, resulting in substantial economic and social burdens. The formation of biofilm has been identified as a major contributor to relapse development. Currently, there is no consensus among German-speaking spinal surgeons or in the existing literature regarding the preferred choice of material to minimize relapse rates. Thus, the objective of this study is to investigate whether certain materials used in spinal implants exhibit varying degrees of susceptibility to bacterial attachment, thereby providing valuable insights for improving treatment outcomes.Eight cages of each PEEK, titanium-coated PEEK (Ti-PEEK), titanium (Ti), polyetherketoneketone (PEKK), tantalum (Ta) and antibiotic-loaded bone cement were incubated with 20% human plasma for 24 h. Subsequently, four implants were incubated with S. aureus for 24 h or 48 h each. The biofilm was then removed by sonication and the attained solution plated for Colony Forming Units (CFU) counting. Scanning electron microscopy was used to confirm bacterial attachment. The CFUs have been compared directly and in relation to the cages surface area. The surface area of the implants was PEEK 557 mm2, Ti-PEEK 472 mm2, Ti 985 mm2, PEKK 594 mm2, Ta 706 mm2, bone cement 123 mm2. The mean CFU count per implant and per mm2 surface area after 24 h and after 48 h was calculated. Bone cement was found to have significantly more CFUs per mm2 surface area than the other materials tested. When comparing the CFU count per implant, bone cement was statistically significantly more prone to biofilm formation than PEEK after 48 h. There was no statistical significance between the other materials when comparing both CFU count per mm2 surface area and CFU count per implant. The electron microscopic analysis showed the attachment of the bacteria, as well as production of extracellular polymeric substances (EPS) as a sign for beginning biofilm formation. Antibiotic-loaded bone cement has shown statistically significantly more bacterial attachment than the other examined materials. No difference was found between the other materials regarding bacterial attachment after 24 h and 48 h. Proposed hypotheses for further studies include testing whether differences become apparent after longer incubation or with different pathogens involved in the pathogenesis of pyogenic spondylodiscitis.

Assessment of Vibrionaceae prevalence in seafood from Qidong market and analysis of Vibrio parahaemolyticus strains.

The aim of this study was to investigate the prevalence of Vibrionaceae family in retail seafood products available in the Qidong market during the summer of 2023 and to characterize Vibrio parahaemolyticus isolates, given that this bacterium is the leading cause of seafood-associated food poisoning. We successfully isolated a total of 240 Vibrionaceae strains from a pool of 718 seafood samples. The breakdown of the isolates included 146 Photobacterium damselae, 59 V. parahaemolyticus, 18 V. campbellii, and 11 V. alginolyticus. Among these, P. damselae and V. parahaemolyticus were the predominant species, with respective prevalence rates of 20.3% and 8.2%. Interestingly, all 59 isolates of V. parahaemolyticus were identified as non-pathogenic. They demonstrated proficiency in swimming and swarming motility and were capable of forming biofilms across a range of temperatures. In terms of antibiotic resistance, the V. parahaemolyticus isolates showed high resistance to ampicillin, intermediate resistance to cefuroxime and cefazolin, and were sensitive to the other antibiotics evaluated. The findings of this study may offer valuable insights and theoretical support for enhancing seafood safety measures in Qidong City.

Discovery and engineering of a novel peptide, Temporin-WY2, with enhanced in vitro and in vivo efficacy against multi-drug resistant bacteria.

Infections by drug-resistant microorganisms are a threat to global health and antimicrobial peptides are considered to be a new hope for their treatment. Temporin-WY2 was identified from the cutaneous secretion of the Ranidae frog, Amolops wuyiensis. It presented with a potent anti-Gram-positive bacterial efficacy, but its activity against Gram-negative bacteria and cancer cell lines was unremarkable. Also, it produced a relatively high lytic effect on horse erythrocytes. For further improvement of its functions, a perfect amphipathic analogue, QUB-1426, and two lysine-clustered analogues, 6K-WY2 and 6K-1426, were synthesised and investigated. The modified peptides were found to be between 8- and 64-fold more potent against Gram-negative bacteria than the original peptide. Additionally, the 6K analogues showed a rapid killing rate. Also, their antiproliferation activities were more than 100-fold more potent than the parent peptide. All of the peptides that were examined demonstrated considerable biofilm inhibition activity. Moreover, QUB-1426, 6K-WY2 and 6K-1426, demonstrated in vivo antimicrobial activity against MRSA and E. coli in an insect larvae model. Despite observing a slight increase in the hemolytic activity and cytotoxicity of the modified peptides, they still demonstrated a improved therapeutic index. Overall, QUB-1426, 6K-WY2 and 6K-1426, with dual antimicrobial and anticancer functions, are proposed as putative drug candidates for the future.

Mining and multifaceted applications of phage lysin for combatting Vibrio parahaemolyticus.

Vibrio parahaemolyticus, a prevalent foodborne pathogen found in both water and seafood, poses substantial risks to public health. The conventional countermeasure, antibiotics, has exacerbated the issue of antibiotic resistance, increasing the difficulty of controlling this bacterium. Phage lysins, as naturally occurring active proteins, offer a safe and reliable strategy to mitigate the impact of V. parahaemolyticus on public health. However, there is currently a research gap concerning bacteriophage lysins specific to Vibrio species. To address this, our study innovatively and systematically evaluates 37 phage lysins sourced from the NCBI database, revealing a diverse array of conserved domains and notable variations in similarity among Vibrio phage lysins. Three lysins, including Lyz_V_pgrp, Lyz_V_prgp60, and Lyz_V_zlis, were successfully expressed and purified. Optimal enzymatic activity was observed at 45℃, 800 mM NaCl, and pH 8-10, with significant enhancements noted in the presence of 1 mM membrane permeabilizers such as EDTA or organic acids. These lysins demonstrated effective inhibition against 63 V. parahaemolyticus isolates from clinical, food, and environmental sources, including the reversal of partial resistance, synergistic interactions with antibiotics, and disruption of biofilms. Flow cytometry analyses revealed that the combination of Lyz_V_pgp60 and gentamicin markedly increased bacterial killing rates. Notably, Lyz_V_pgrp, Lyz_V_pgp60, and Lyz_V_zlis exhibited highly efficient biofilm hydrolysis, clearing over 90 % of preformed V. parahaemolyticus biofilms within 48 h. Moreover, these lysins significantly reduced bacterial loads in various food samples and environmental sources, with reductions averaging between 1.06 and 1.29 Log CFU/cm2 on surfaces such as stainless-steel and bamboo cutting boards and approximately 0.87 CFU/mL in lake water and sediment samples. These findings underscore the exceptional efficacy and versatile application potential of phage lysins, offering a promising avenue for controlling V. parahaemolyticus contamination in both food and environmental contexts.

Characterization of emetic Bacillus cereus biofilm formation and cereulide production in biofilm.

Bacillus cereus is a well-known foodborne pathogen that can cause human diseases, including vomiting caused by emetic toxin, cereulide, requiring 105-108 cells per gram to cause the disease. The bacterial cells may be eliminated during processing, but cereulide can survive in most processing techniques due to its resistance to high temperatures, extreme pH and proteolytic enzymes. Herein, we reported dynamic processes of biofilm formation of four different types and cereulide production within the biofilm. Confocal laser scanning microscopy (CLSM) images revealed that biofilms of the four different types reach each stage at different time points. Among the extracellular polymeric substances (EPS) components of the four biofilms formed by the emetic B. cereus F4810/72 strain, proteins account for the majority. In addition, there are significant differences (p < 0.05) in the EPS components at the same stage among biofilms of different types. The time point at which cereulide was first detected in the four types of biofilms was 24 h. In the biofilm of B. cereus formed in ultra-high-temperature (UHT) milk, the first peak of cereulide appeared at 72 h. The cereulide content of the biofilms formed in BHI was mostly higher than that of the biofilms formed in UHT milk. This study contributes to a better understanding of food safety issues in the industry caused by biofilm and cereulide toxin produced by B. cereus.

The combined effect of pH and NaCl on the susceptibility of Listeria monocytogenes to rhamnolipids.

The use of natural and sustainable additives, that are less aggressive to the environment, is a trend in the food industry. Rhamnolipids (RL) biosurfactants have shown potential for controlling food pathogens however, due to the presence of free carboxyl groups, the pH and ionic strength may influence the properties of such surfactants. In this study, we describe the antimicrobial activity of RL under different pH values and NaCl concentrations, towards both planktonic and biofilms of Listeria monocytogenes. RL were effective at pH 5.0 and the addition of 5 % NaCl improved the bactericidal efficacy for planktonic and sessile cells. The effect of NaCl was more pronounced at pH above 6 showing a significant increase in RL antimicrobial activity. At pH 7.0 planktonic population was eradicated by RL only when salt was present whereas biofilm viability was decreased by 5 log with MBIC varying from > 2500.0 mg/L (RL) to 39.0 mg/L (RL + 5 % NaCl). Larger vesicular and lamellar RL self-assembly structures were predominant when NaCl was present, suggesting their association with the antimicrobial activity observed. The pH and ionic strength of the medium are important parameters to be considered for the development of RL-based strategies to control L. monocytogenes.

Pretreatment for potable reuse: Enhancing the biological removal of 1,4-dioxane from landfill leachate through cometabolism with tetrahydrofuran.

1,4-Dioxane is a probable human carcinogen and a persistent aquatic contaminant. Cometabolic biodegradation of 1,4-dioxane is a promising low-cost and effective treatment technology; however, further demonstration is needed for treating landfill leachate. This technology was tested in two full-scale moving bed biofilm reactors (MBBRs) treating raw landfill leachate with tetrahydrofuran selected as the cometabolite. The raw leachate contained on average 82 µg/L of 1,4-dioxane and before testing the MBBRs removed an average of 38% and 42% of 1,4-dioxane, respectively. First, tetrahydrofuran was added to MBBR 1, and 1,4-dioxane removal was improved to an average of 73%, with the control MBBR removing an average of 37% of 1,4-dioxane. During this period, an optimal dose of 2 mg/L of tetrahydrofuran was identified. Tetrahydrofuran was then fed to both MBBRs, where the 1,4-dioxane removal was on average 73% and 80%. Cometabolic treatment at the landfill significantly reduced the concentration of 1,4-dioxane received from the landfill at a downstream wastewater treatment and indirect potable reuse facility, reducing the load of 1,4-dioxane from 44% to 24% after the study. PRACTITIONER POINTS: Cometabolic degradation of leachate 1,4-dioxane with THF in MBBRs is a feasible treatment technology and a low-cost technique when retrofitting existing biological treatment facilities. The MBBRs can be operated at a range of temperatures, require no operational changes beyond THF addition, and operate best at a mass ratio of THF to 1,4-dioxane of 24. Source control of 1,4-dioxane significantly reduces the concentration of 1,4-dioxane in downstream wastewater treatment plants and potable reuse facilities.

BBSdb, an open resource for bacterial biofilm-associated proteins.

Bacterial biofilms are organized heterogeneous assemblages of microbial cells encased within a self-produced matrix of exopolysaccharides, extracellular DNA and proteins. Over the last decade, more and more biofilm-associated proteins have been discovered and investigated. Furthermore, omics techniques such as transcriptomes, proteomes also play important roles in identifying new biofilm-associated genes or proteins. However, those important data have been uploaded separately to various databases, which creates obstacles for biofilm researchers to have a comprehensive access to these data. In this work, we constructed BBSdb, a state-of-the-art open resource of bacterial biofilm-associated protein. It includes 48 different bacteria species, 105 transcriptome datasets, 21 proteome datasets, 1205 experimental samples, 57,823 differentially expressed genes (DEGs), 13,605 differentially expressed proteins (DEPs), 1,930 'Top 5% differentially expressed genes', 444 'Threshold-based DEGs' and a predictor for prediction of biofilm-associated protein. In addition, 1,781 biofilm-associated proteins, including annotation and sequences, were extracted from 942 articles and public databases via text-mining analysis. We used E. coli as an example to represent how to explore potential biofilm-associated proteins in bacteria. We believe that this study will be of broad interest to researchers in field of bacteria, especially biofilms, which are involved in bacterial growth, pathogenicity, and drug resistance. Availability and implementation: The BBSdb is freely available at http://124.222.145.44/#!/.

Corrosion behavior of predominant Halodesulfovibrio in a marine SRB consortium and its mitigation using ZnO nanoparticles.

Formation of Sulfate Reducing Bacteria (SRB) biofilm accelerates microbiologically influenced corrosion (MIC). The aim of this study was to investigate both the corrosivity of a marine SRB consortium on carbon steel coupons and its mitigation in the presence of ZnO. Metagenomics analysis revealed that Halodesulfovibrio (78.9%) was predominant and could be related to MIC. The analysis also showed a remarkable shift from a highly corrosive SRB consortium in the control bioreactors to a far less corrosive consortium when ZnO was added to the bioreactors. Further results indicated that the corrosion rate of the SRB consortium was 8.17 mpy on the carbon steel coupons. In the ZnO-treated bioreactors, the count of SRB and MIC in the carbon steel coupons simultaneously reduced. Moreover, Confocal Laser Scanning Microscopy and profilometry analysis determined that ZnO could significantly decrease the amount of biofilm and the corrosion rate. Electrochemical experiments revealed higher corrosion current density (icorr) and lower charge transfer resistance (Rct) in the control bioreactors relative to the ZnO-treated bioreactors. We introduce Halodesulfovibrio as a potentially important corrosive genus in a marine SRB consortium. Additionally, ZnO could be considered a proper candidate to control the corrosion induced by Halodesulfovibrio.

Antibiotic resistance and epidemiological characteristics of polymyxin-resistant Klebsiella pneumoniae. / è€å¤šé»èŒç´ è‚ºç‚Žå ‹é›·ä¼¯èŒçš„è¯æ•ç‰¹å¾åŠæµè¡Œç— å­¦ç‰¹ç‚¹.

OBJECTIVES: The emergence of polymyxin-resistant Klebsiella pneumoniae (KPN) in clinical settings necessitates an analysis of its antibiotic resistance characteristics, epidemiological features, and risk factors for its development. This study aims to provide insights for the prevention and control of polymyxin-resistant KPN infections. METHODS: Thirty clinical isolates of polymyxin-resistant KPN were collected from the Third Xiangya Hospital of Central South University. Their antibiotic resistance profiles were analyzed. The presence of carbapenemase KPC, OXA-48, VIM, IMP, and NDM was detected using colloidal gold immunochromatography. Hypervirulent KPN was initially screened using the string test. Biofilm formation capacity was assessed using crystal violet staining. Combination drug susceptibility tests (polymyxin B with meropenem, tigecycline, cefoperazone/sulbactam) were conducted using the checkerboard method. Polymyxin-related resistance genes were detected by PCR. Multi-locus sequence typing (MLST) was performed for genotyping and phylogenetic tree construction. The study also involved collecting data from carbapenem-resistant (CR)-KPN polymyxin-resistant strains (23 strains, experimental group) and CR-KPN polymyxin-sensitive strains (57 strains, control group) to analyze potential risk factors for polymyxin-resistant KPN infection through univariate analysis and multivariate Logistic regression. The induction of resistance by continuous exposure to polymyxin B and colistin E was also tested. RESULTS: Among the 30 polymyxin-resistant KPN isolates, 28 were CR-KPN, all producing KPC enzyme. Four isolates were positive in the string test. Most isolates showed strong biofilm formation capabilities. Combination therapy showed additive or synergistic effects. All isolates carried the pmrA and phoP genes, while no mcr-1 or mcr-2 genes were detected. MLST results indicated that ST11 was the predominant type. The phylogenetic tree suggested that polymyxin-resistant KPN had not caused a hospital outbreak in the institution. The use of two or more different classes of antibiotics and the use of polymyxin were identified as independent risk factors for the development of polymyxin-resistant strains. Continuous use of polymyxin induced drug resistance. CONCLUSIONS: Polymyxin-resistant KPN is resistant to nearly all commonly used antibiotics, making polymyxin-based combination therapy a viable option. No plasmid-mediated polymyxin-resistant KPN has been isolated in the hospital. Polymyxin can induce resistance in KPN, highlighting the need for rational antibiotic use in clinical settings to delay the emergence of resistance.

Comparison of the efficacy of Er,Cr:YSGG laser on oral biofilm removal from implant surfaces with various application times for the treatment of peri-implantitis defects: ex vivo study.

PURPOSE: The major struggle in peri-implantitis therapy is the availability of successful decontamination of the infected implant surface. The main hypothesis of this study was the Er,Cr: YSGG laser decontamination efficacy investigation on the infected implant surfaces with various peri-implantitis defects. The primary objective of this study was to decide the efficacy of Er,Cr:YSGG laser as a decontamination tool at various peri-implantitis simulating defects. The secondary objective was to compare the efficacy of the Er,Cr: YSGG laser on oral biofilm removal between two protocols the first protocol (4 cycles at 2.5 min) and the second protocol (5 cycles at 5 min) at various peri-implantitis simulating defects. MATERIALS AND METHODS: A total of 3 subjects whose plaque biofilms formed in-vivo on twenty-four tested implants were divided into four tested groups. Two native implants were tested as controls.The in vitro defect model was computer-aided designed and printed into a 3D-printed model with various anulations in peri-implant infrabony defects, which were 15,30,60,and 90 degrees. RESULTS: Both Er, Cr: YSGG decontamination protocols at 50 mJ (1.5 W/30 Hz), 50% air, and 40% water were effective at reducing the total implant surface area/ biofilm ratio (%), but the second protocol had a markedly greater reduction in the duration of application (5 cycles at 5 min) than did the first protocol (4 cycles at 2.5 min). CONCLUSION: The Er, Cr: YSGG laser is an effective decontamination device in various peri-implantitis defects. The second protocol(5 cycles at 5 min) with greater application time and circles is more effective than the first one. The defect angulation influence the decontamination capability in peri-implantitis therapy. CLINICAL RELEVANCE (SCIENTIFIC RATIONALE FOR STUDY): Clinicians anticipate that the exploration of suitable therapeutic modalities for peri-implantitis therapy is limited by the obvious heterogeneity of the available evidence in the literature and need for a pre-clinical theoretical basis setup. The major challenges associated with peri-implantitis therapy include the successful decontamination of the infected implant surface, the absence of any damage to the treated implant surface with adequate surface roughness, and the biocompatibility of the implant surface, which allows osteoblastic cells to grow on the treated surface and is the key for successful re-osseointegration. Therefore, these are the expected empirical triads that need to be respected for successful peri-implantitis therapy. Failure of one of the triads represents a peri-implantitis therapeutic failure. The Er, Cr: YSGG laser is regarded as one of the expected devices for achieving the required triad. TRIAL REGISTRATION: "Efficacy of Er,Cr YSGG Laser in Treatment of Peri-implantitis". CLINICALTRIALS: gov ID NCT05137821. First Posted date: 30 -11-2021.

New insights into N2O emission and electron competition under different chemical oxygen demand to nitrogen ratios in a biofilm system.

Nitrous oxide (N2O) is a greenhouse gas that could accumulate during the heterotrophic denitrification process. In this study, the effects of different chemical oxygen demand to nitrogen ratio (COD/N) on N2O production and electron competition was investigated. The electron competition was intensified with the decrease of electron supply, and Nos had the best electron competition ability. The model simulation results indicated that the degradation of NOx-Ns was a combination of diffusion and biological degradation. As reaction proceeding, N2O could accumulate inside biofilm. A thinner biofilm and a longer hydraulic retention time (HRT) might be an effective way to control N2O emission. The application of mathematical model is an opportunity to gain deep understanding of substrate degradation and electron competition inside biofilm.

Phenanthrenes from Juncus articulatus with Antibacterial and Biofilm Formation Inhibitory Activity.

Continuing our search for bioactive compounds in species from the Juncaceae family, Juncus articulatus was investigated. Ten previously undescribed phenanthrenes─articulins A-J (1-10)─and ten known compounds─juncuenin B, dehydrojuncuenin B, juncatrin B, ensifolins E, F, H, I, K, juncuenin D, and luzulin A (11-20)─along with other compounds, have been isolated and identified. The isolated compounds were evaluated for antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, methicillin-susceptible Staphylococcus aureus (MSSA), and methicillin-resistant Staphylococcus aureus (MRSA). Compounds 12 and 14 exhibited the most potent activity against planktonic and sessile MSSA and MRSA with minimum inhibitory concentration (MIC) values of 15.1 µM (12 for both bacterial strains) and 15.3 µM (14 for both bacterial strains). Compounds 15, 17, and 18 also exhibited activity against both strains, although to a lower extent, with MIC values ranging from 30.0 to 56.8 µM. The inhibition of biofilm formation of these compounds was observed at 15.1-114.3 µM. This study elucidates the phenanthrene composition of J. articulatus and the antibacterial effect of these compounds.

Amorphous TiO2nano-coating on stainless steel to improve its biological response.

This study delves into the potential of amorphous titanium oxide (aTiO2) nano-coating to enhance various critical aspects of non-Ti-based metallic orthopedic implants. These implants, such as medical-grade stainless steel (SS), are widely used for orthopedic devices that demand high strength and durability. The aTiO2nano-coating, deposited via magnetron sputtering, is a unique attempt to improve the osteogenesis, the inflammatory response, and to reduce bacterial colonization on SS substrates. The study characterized the nanocoated surfaces (SS-a TiO2) in topography, roughness, wettability, and chemical composition. Comparative samples included uncoated SS and sandblasted/acid-etched Ti substrates (Ti). The biological effects were assessed using human mesenchymal stem cells (MSCs) and primary murine macrophages. Bacterial tests were carried out with two aerobic pathogens (S. aureusandS. epidermidis) and an anaerobic bacterial consortium representing an oral dental biofilm. Results from this study provide strong evidence of the positive effects of the aTiO2nano-coating on SS surfaces. The coating enhanced MSC osteoblastic differentiation and exhibited a response similar to that observed on Ti surfaces. Macrophages cultured on aTiO2nano-coating and Ti surfaces showed comparable anti-inflammatory phenotypes. Most significantly, a reduction in bacterial colonization across tested species was observed compared to uncoated SS substrates, further supporting the potential of aTiO2nano-coating in biomedical applications. The findings underscore the potential of magnetron-sputtering deposition of aTiO2nano-coating on non-Ti metallic surfaces such as medical-grade SS as a viable strategy to enhance osteoinductive factors and decrease pathogenic bacterial adhesion. This could significantly improve the performance of metallic-based biomedical devices beyond titanium.

In Situ Biofilm Affinity-Based Protein Profiling Identifies the Streptococcal Hydrolase GbpB as the Target of a Carolacton-Inspired Chemical Probe.

Natural products are important precursors for antibiotic drug design. These chemical scaffolds serve as synthetic inspiration for chemists who leverage their structures to develop novel antibacterials and chemical probes. We have previously studied carolacton, a natural product macrolactone fromSorangium cellulosum, and discovered a simplified derivative, A2, that maintained apparent biofilm inhibitory activity, although the biological target was unknown. Herein, we utilize affinity-based protein profiling (AfBPP) in situ during biofilm formation to identify the protein target using a photoexcitable cross-linking derivative of A2. From these studies, we identified glucan binding protein B (GbpB), a peptidoglycan hydrolase, as the primary target of A2. Further characterization of the interaction between A2 and GbpB, as well as PcsB, a closely related homologue from the more pathogenic S. pneumoniae, revealed binding to the catalytic CHAP (cysteine, histidine, aminopeptidase) domain. To the best of our knowledge, this is the first report of a small-molecule binder of a conserved and essential bacterial CHAP hydrolase, revealing its potential as an antibiotic target. This work also highlights A2 as a useful tool compound for streptococci and as an initial scaffold for the design of more potent CHAP binders.

Preliminary study of microbiologically influenced corrosion by Pseudomonas aeruginosa on high Chromium white iron.

Microbiologically Influenced Corrosion (MIC) poses a significant challenge to various industries, leading to substantial economic losses and potential safety hazards. Despite extensive research on the MIC resistance of various materials, there is a lack of studies focusing on High Chromium White Iron (HCWI) alloys, which are widely used in wear-resistant applications. This study addresses this knowledge gap by providing a comprehensive investigation of the MIC resistance of three HCWI alloys with varying chromium contents (22 wt%, 30.7 wt%, and 21 wt%) in the presence of Pseudomonas aeruginosa (P. Aeruginosa), a common bacterial species associated with MIC. The alloys were exposed to an artificial seawater medium inoculated with P.Aeruginosa for 14 days, and their corrosion behaviour was evaluated using electrochemical techniques, surface analysis, and microscopy. Electrochemical Impedance Spectroscopy (EIS) results revealed that the alloy with the highest chromium content (A2, 30.7 wt% Cr) exhibited superior MIC resistance compared to the other alloys (A1, 22 wt% Cr and M1, 21 wt% Cr). The enhanced performance of alloy A2 was attributed to the formation of a more stable and protective passive film, as well as the development of a more compact and less permeable biofilm. The EIS data, interpreted using equivalent circuit models, showed that alloy A2 had the highest charge transfer resistance and the lowest biofilm capacitance, indicating a more effective barrier against corrosive species. Bode plots further confirmed the superior corrosion resistance of alloy A2, with higher impedance values and phase angles at low frequencies compared to alloys A1 and M1. Scanning Electron Microscopy (SEM) and optical microscopy analyses corroborated these findings, showing that alloy A2 had the lowest pit density and size after 14 days of exposure. The insights gained from this study highlight the critical role of chromium content in the MIC resistance of HCWI alloys and have significant implications for the design and selection of materials for applications prone to microbial corrosion.

A potential therapeutic strategy of an innovative probiotic formulation toward topical treatment of diabetic ulcer: an in vivo study.

BACKGROUND: The probiotic potential of Lacticacid bacteria has been studied in various medical complications, from gastrointestinal diseases to antibiotic resistance infections recently. Moreover, diabetic ulcer (DU) is known as one of the most significant global healthcare concerns, which comprehensively impacts the quality of life for these patients. Given that the conventional treatments of DUs have failed to prevent later complications completely, developing alternative therapies seems to be crucial. METHODS: We designed the stable oleogel-based formulation of viable probiotic cells, including Lactobacillus rhamnosus (L. rhamnosus), Lactobacillus casei (L. casei), Lactobacillus fermentum (L. fermentum), and Lactobacillus acidophilus (L. acidophilus) individually to investigate their effect on wound healing process as an in vivo study. The wound repair process was closely monitored regarding morphology, biochemical, and histopathological changes over two weeks and compared it with the effects of topical tetracycline as an antibiotic approach. Furthermore, the antibiofilm activity of probiotic bacteria was assessed against some common pathogens. RESULTS: The findings indicated that all tested lactobacillus groups (excluded L. casei) included in the oleogel-based formulation revealed a high potential for repairing damaged skin due to the considerably more levels of hydroxyproline content of tissue samples along with the higher numerical density of mature fibroblasts cell and volume density of hair follicles, collagen fibrils, and neovascularization in comparison with antibiotic and control groups. L. acidophilus and L. rhamnosus showed the best potential of wound healing among all lactobacillus species, groups treated by tetracycline and control groups. Besides, L. rhamnosus showed a significant biofilm inhibition activity against tested pathogens. CONCLUSIONS: This experiment demonstrated that the designed formulations containing probiotics, particularly L. acidophilus and L. rhamnosus, play a central role in manipulating diabetic wound healing. It could be suggested as an encouraging nominee for diabetic wound-healing alternative approaches, though further studies in detailed clinical trials are needed.

H-NS is a bacterial transposon capture protein.

The histone-like nucleoid structuring (H-NS) protein is a DNA binding factor, found in gammaproteobacteria, with functional equivalents in diverse microbes. Universally, such proteins are understood to silence transcription of horizontally acquired genes. Here, we identify transposon capture as a major overlooked function of H-NS. Using genome-scale approaches, we show that H-NS bound regions are transposition "hotspots". Since H-NS often interacts with pathogenicity islands, such targeting creates clinically relevant phenotypic diversity. For example, in Acinetobacter baumannii, we identify altered motility, biofilm formation, and interactions with the human immune system. Transposon capture is mediated by the DNA bridging activity of H-NS and, if absent, more ubiquitous transposition results. Consequently, transcribed and essential genes are disrupted. Hence, H-NS directs transposition to favour evolutionary outcomes useful for the host cell.

Tad pili contribute to the virulence and biofilm formation of virulent Aeromonas hydrophila.

Type IV pili (T4P) are versatile proteinaceous protrusions that mediate diverse bacterial processes, including adhesion, motility, and biofilm formation. Aeromonas hydrophila, a Gram-negative facultative anaerobe, causes disease in a wide range of hosts. Previously, we reported the presence of a unique Type IV class C pilus, known as tight adherence (Tad), in virulent Aeromonas hydrophila (vAh). In the present study, we sought to functionalize the role of Tad pili in the pathogenicity of A. hydrophila ML09-119. Through a comprehensive comparative genomics analysis of 170 A. hydrophila genomes, the conserved presence of the Tad operon in vAh isolates was confirmed, suggesting its potential contribution to pathogenicity. Herein, the entire Tad operon was knocked out from A. hydrophila ML09-119 to elucidate its specific role in A. hydrophila virulence. The absence of the Tad operon did not affect growth kinetics but significantly reduced virulence in catfish fingerlings, highlighting the essential role of the Tad operon during infection. Biofilm formation of A. hydrophila ML09-119 was significantly decreased in the Tad operon deletant. Absence of the Tad operon had no effect on sensitivity to other environmental stressors, including hydrogen peroxide, osmolarity, alkalinity, and temperature; however, it was more sensitive to low pH conditions. Scanning electron microscopy revealed that the Tad mutant had a rougher surface structure during log phase growth than the wildtype strain, indicating the absence of Tad impacts the outer surface of vAh during cell division, of which the biological consequences are unknown. These findings highlight the role of Tad in vAh pathogenesis and biofilm formation, signifying the importance of T4P in bacterial infections.