Contribution of the hydrophobic effect to microbial infection

Colonization characteristics and surface effects of microplastic biofilms: Implications for environmental behavior of typical pollutants

This paper summarizes the colonization dynamics of biofilms on microplastics (MPs) surfaces in aquatic environments, encompassing bacterial characteristics, environmental factors affecting biofilm formation, and matrix types and characteristics. The interaction between biofilm and MPs was also discussed. Through summarizing recent literatures, it was found that MPs surfaces offer numerous benefits to microorganisms, including nutrient enrichment and enhanced resistance to environmental stress. Biofilm colonization changes the surface physical and chemical properties as well as the transport behavior of MPs. At the same time, biofilms also play an important role in the fragmentation and degradation of MPs. In addition, we also investigated the coexistence level, adsorption mechanism, enrichment, and transformation of MPs by environmental pollutants mediated by biofilms. Moreover, an interesting aspect about the colonization of biofilms was discussed. Biofilm colonization not only had a great effect on the accumulation of heavy metals by MPs, but also affects the interaction between particles and environmental pollutants, thereby changing their toxic effects and increasing the difficulty of MPs treatment. Consequently, further attention and research are warranted to delve into the internal mechanisms, environmental risks, and the control of the coexistence of MPs and biofilms.

Exploring the Effectiveness of Hydrophobic Glass Surface on Touch-Enabled Digital Device to Reduce Microbial Adhesion and Propagation

This study investigates the effectiveness of hydrophobic glass surfaces in reducing microbial populations on touch-enabled digital devices. Hydrophobic coatings have been proposed as a potential solution to minimize microbial adhesion and growth on device surfaces. Here, we intended to investigate the effect of hydrophobic spray on microbial load. The results were quantitatively analyzed using microbiological techniques. the nonhydrophobic surface harbors gradual microbial buildup upon time, such as threefold increase from 2 to 4 h and fivefold increase to 6 h post initial sampling with 143.6 ± 33.89 cfu/ml increase up to 264.7 ± 28.53 cfu/ml, whereas the hydrophobic surface had an overall build-up from 16.6 ± 1.2 to 50.45 ± 11.12 cfu/ml with P < 0.0001 significance. This research provides valuable insights into the potential application of hydrophobic glass coatings to mitigate microbial contamination on touch-enabled digital devices, enhancing their hygienic properties and minimizing the risk of infectious disease transmission.

Antimicrobial and antibiofilm activities of chromone derivatives against uropathogenic Escherichia coli

Uropathogenic Escherichia coli (UPEC) is a urinary tract pathogen responsible for most nosocomial urinary tract infections and can cause severe conditions like acute cystitis of the bladder or pyelonephritis. UPEC harbors a host of virulence factors like curli, hemolysin, siderophore, and motility factors and can form biofilm-like communities and quiescent reservoirs that aid its survival. This study was performed to investigate the antibiofilm, antimicrobial, and antivirulence potentials of three chromone derivatives, namely, 6-bromo 3-formylchromone, 6-chloro 3-formylchromone, and 3-formyl 6-isopropylchromone. These chromones had MICs against UPEC of 20, 20, and 50 µg/ml, respectively, inhibited biofilm formation by 72-96% at 20 µg/ml, and inhibited UPEC-associated virulence factors, that is, hemolysis, motility, curli, siderophore production, indole production, quiescent colony formation, and cell surface hydrophobicity. Gene expression analysis indicated these three derivatives downregulated virulence genes associated with toxins, biofilm production, and stress regulation and suggested they might target two-component UvrY response regulator. 3D-QSAR analysis showed that substitutions at the third and sixth positions of the chromone scaffold favor antimicrobial activity against UPEC. Furthermore, ADME profiles and C. elegans cytotoxicity assays indicated that these chromone derivatives are potent, safe drug candidates.

The effect of polyethylene microplastics on the disinfection of Escherichia coli by sodium hypochlorite

The effect of polyethylene microplastics (PE-MPs) on the disinfection of Escherichia coli (E. coli) by sodium hypochlorite was investigated in different pH value, ionic strength, and NOM concentration to illustrate the impact of MPs on the pathogenic bacteria disinfection efficiency in nature water environment. The results showed that PE-MPs tended to agglomerate rather than disperse due to their strong hydrophobicity in water. Within 30 s, about 1.5 log₁₀ of E. coli was adsorbed on the surface of PE-MPs, forming subsequent protection for E. coli. Thus, the presence of PE-MPs reduced the inactivation rate of E. coli. As for the particle-free solutions, the higher solution pH, the presence of natural organic matter (NOM), and the higher concentrations of cations (monovalent Na⁺ and divalent Ca²⁺) were confirmed as the major influencing factors decreasing the E. coli disinfection efficiency. However, due to the adsorption and protection of PE-MPs on E. coli, the influences of complex chemistry factors on the inactivation of E. coli were reduced. The inactivation of E. coli in PE-MPs (20 NTU) solution was 1 log₁₀ lower than that in particle-free solution under the same water quality conditions. Therefore, considering the complex water chemistry, the existence of MPs could be a potential challenge for disinfection efficiency in the water treatment plants.

Antibiofilm and Antimicrobial Activities of Chloroindoles Against Uropathogenic Escherichia coli

Uropathogenic Escherichia coli (UPEC) is a nosocomial pathogen associated with urinary tract infections and expresses several virulence factors that cause recurring infections and cystitis of the bladder, which can lead to pyelonephritis. UPEC uses different types of extracellular appendages like fimbriae and pili that aid colonization and adherence to bladder epithelium and can form persistent biofilm-like bacterial communities that aid its survival after the deployment of host immune responses. We investigated the antibiofilm, antimicrobial, and antivirulence properties of three indole derivatives namely, 4-chloroindole, 5-chloroindole, and 5-chloro 2-methyl indole. All the three chloroindoles had MICs of 75 μg/ml and inhibited biofilm formation by an average of 67% at 20 μg/ml. In addition, they inhibited swarming and swimming motilities, which are essential for dissemination from bacterial communities and colonization, reduced cell surface hydrophobicity, and inhibited indole production and curli formation. Gene expression analysis showed all three chloroindoles significantly downregulated the expressions of virulence genes associated with adhesion, stress regulation, and toxin production. A 3D-QSAR analysis revealed substitutions at the fourth and fifth positions of the indole moiety favored antimicrobial activity. Furthermore, these chloroindoles potently inhibited biofilm formation in other nosocomial pathogens and polymicrobial consortia.

Lessons From Insect Fungiculture: From Microbial Ecology to Plastics Degradation

Anthropogenic activities have extensively transformed the biosphere by extracting and disposing of resources, crossing boundaries of planetary threat while causing a global crisis of waste overload. Despite fundamental differences regarding structure and recalcitrance, lignocellulose and plastic polymers share physical-chemical properties to some extent, that include carbon skeletons with similar chemical bonds, hydrophobic properties, amorphous and crystalline regions. Microbial strategies for metabolizing recalcitrant polymers have been selected and optimized through evolution, thus understanding natural processes for lignocellulose modification could aid the challenge of dealing with the recalcitrant human-made polymers spread worldwide. We propose to look for inspiration in the charismatic fungal-growing insects to understand multipartite degradation of plant polymers. Independently evolved in diverse insect lineages, fungiculture embraces passive or active fungal cultivation for food, protection, and structural purposes. We consider there is much to learn from these symbioses, in special from the community-level degradation of recalcitrant biomass and defensive metabolites. Microbial plant-degrading systems at the core of insect fungicultures could be promising candidates for degrading synthetic plastics. Here, we first compare the degradation of lignocellulose and plastic polymers, with emphasis in the overlapping microbial players and enzymatic activities between these processes. Second, we review the literature on diverse insect fungiculture systems, focusing on features that, while supporting insects' ecology and evolution, could also be applied in biotechnological processes. Third, taking lessons from these microbial communities, we suggest multidisciplinary strategies to identify microbial degraders, degrading enzymes and pathways, as well as microbial interactions and interdependencies. Spanning from multiomics to spectroscopy, microscopy, stable isotopes probing, enrichment microcosmos, and synthetic communities, these strategies would allow for a systemic understanding of the fungiculture ecology, driving to application possibilities. Detailing how the metabolic landscape is entangled to achieve ecological success could inspire sustainable efforts for mitigating the current environmental crisis.

Mycobacterial Adhesion: From Hydrophobic to Receptor-Ligand Interactions

Adhesion is crucial for the infective lifestyles of bacterial pathogens. Adhesion to non-living surfaces, other microbial cells, and components of the biofilm extracellular matrix are crucial for biofilm formation and integrity, plus adherence to host factors constitutes a first step leading to an infection. Adhesion is, therefore, at the core of pathogens’ ability to contaminate, transmit, establish residency within a host, and cause an infection. Several mycobacterial species cause diseases in humans and animals with diverse clinical manifestations. Mycobacterium tuberculosis, which enters through the respiratory tract, first adheres to alveolar macrophages and epithelial cells leading up to transmigration across the alveolar epithelium and containment within granulomas. Later, when dissemination occurs, the bacilli need to adhere to extracellular matrix components to infect extrapulmonary sites. Mycobacteria causing zoonotic infections and emerging nontuberculous mycobacterial pathogens follow divergent routes of infection that probably require adapted adhesion mechanisms. New evidence also points to the occurrence of mycobacterial biofilms during infection, emphasizing a need to better understand the adhesive factors required for their formation. Herein, we review the literature on tuberculous and nontuberculous mycobacterial adhesion to living and non-living surfaces, to themselves, to host cells, and to components of the extracellular matrix.

Effect of a DACC-coated dressing on keratinocytes and fibroblasts in wound healing using an in vitro scratch model

Wound dressings that exert an antimicrobial effect in order to prevent and treat wound infections can be harmful to the wound healing process. Dressings with hydrophobic coatings, however, have been suggested to both reduce the microbial load and promote the healing process. Therefore, the potential effects of a dialkylcarbamoyl chloride (DACC)-coated dressing on fibroblasts and keratinocytes in wound healing were studied using mechanical scratch wounding of confluent cell layers as an in vitro model. Additionally, gene expression analysis by qRT-PCR was used to elucidate the longitudinal effects of the DACC-coated dressing on cell responses, specifically inflammation, growth factor induction and collagen synthesis. DACC promoted cell viability, did not stick to the cell layers, and supported normal wound healing progression in vitro. In contrast, cells became attached to the uncoated reference material, which inhibited scratch closure. Moreover, DACC slightly induced KGF, VEGF, and GM-CSF expression in HaCaT cells and NHDF. Physiological COL1A1 and COL3A1 gene expression by NHDF was observed under DACC treatment with no observable effect on S100A7 and RNASE7 levels in HaCaT cells. Overall, the DACC coating was found to be safe and may positively influence the wound healing outcome. Graphical abstract.

Growth phase-dependent surface properties of Legionella pneumophila and their role in adhesion to stainless steel coated QCM-D sensors

Legionella pneumophila cell surface hydrophobicity and charge are important determinants of their mobility and persistence in engineered water systems (EWS). These surface properties may differ depending on the growth phase of L. pneumophila resulting in variable adhesion and persistence within EWS. We describe the growth-dependent variations in L. pneumophila cell surface hydrophobicity and surface charge using the microbial adhesion to hydrocarbon assay and microelectrophoresis, respectively, and their role in cell adhesion to stainless steel using a quartz crystal microbalance with dissipation (QCM-D) monitoring instrument. We observed a steady increase in L. pneumophila hydrophobicity during their lifecycle in culture media. Cell surfaces of stationary phase L. pneumophila were significantly more hydrophobic than their lag and midexponential counterparts. No significant changes in L. pneumophila cell surface charge were noted. Morphology of L. pneumophila remained relatively constant throughout their lifecycle. In the QCM-D study, lag and exponential phase L. pneumophila weakly adhered to stainless steel surfaces resulting in viscoelastic layers. In contrast, stationary phase bacteria were tightly and irreversibly bound to the surfaces, forming rigid layers. Our results suggest that the stationary phase of L. pneumophila would highly favour their adhesion to plumbing surfaces and persistence in EWS.

Influence of pipe material on biofilm microbial communities found in drinking water supply system

The biofilms and water samples from a model installation built of PVC-U, PE-HD and cast iron pipes were investigated using standard heterotrophic plate count and 16S rRNA Next Generation Sequencing. The results of the high throughput identification imply that the construction material strongly influences the microbiome composition. PVC-U and PE-HD pipes were dominated with Proteobacteria (54-60%) while the cast pipe was overgrown by Nitrospirae (64%). It was deduced that the plastic pipes create a more convenient environment for the potentially pathogenic taxa than the cast iron. The 7-year old biofilms were described as complex habitats with sharp oxidation-reduction gradients, where co-existence of methanogenic and methanotrophic microbiota takes place. Furthermore, it was found that the drinking water distribution systems (DWDS) are a useful tool for studying the ecology of rare bacterial phyla. New ecophysiological aspects were described for Aquihabitans, Thermogutta and Vampirovibrio. The discrepancy between identity of HPC-derived bacteria and NGS-revealed composition of biofilm and water microbiomes point to the need of introducing new diagnostical protocols to enable proper assessment of the drinking water safety, especially in DWDSs operating without disinfection.

Seeing and Touching the Mycomembrane at the Nanoscale

Mycobacteria have unique cell envelopes, surface properties, and growth dynamics, which all play a part in the ability of these important pathogens to infect, evade host immunity, disseminate, and resist antibiotic challenges. Recent atomic force microscopy (AFM) studies have brought new insights into the nanometer-scale ultrastructural, adhesive, and mechanical properties of mycobacteria. The molecular forces with which mycobacterial adhesins bind to host factors, like heparin and fibronectin, and the hydrophobic properties of the mycomembrane have been unraveled by AFM force spectroscopy studies. Real-time correlative AFM and fluorescence imaging have delineated a complex interplay between surface ultrastructure, tensile stresses within the cell envelope, and cellular processes leading to division. The unique capabilities of AFM, which include subdiffraction-limit topographic imaging and piconewton force sensitivity, have great potential to resolve important questions that remain unanswered on the molecular interactions, surface properties, and growth dynamics of this important class of pathogens.

Insight into probiotic properties of lactic acid bacterial endosymbionts of Apis mellifera L. derived from the Polish apiary

Taking into account that fructophilic lactic acid bacteria (FLAB) can play an important role in the health of honey bees and can be used as probiotics, phenotypic properties of probiotic interest of Lactobacillus kunkeei (12 strains) and Fructobacillus fructossus bacteria (2 strains), isolated from Apis mellifera gastrointestinal tract, have been studied. We have evaluated survival of tested FLAB in honey bee gut, their susceptibility to antibiotics (ampicillin, erythromycin, tylosin), cell surface hydrophobicity, auto-aggregation ability, co-aggregation with model pathogenic bacteria, biofilm formation capacity, and effect of studied FLAB, added to sucrose syrup bee diet, on longevity of honey bees. The tested FLAB exhibited good gastrointestinal tract tolerance and high antibiotic susceptibility, which are important criteria in the screening of probiotic candidates. It was also found that all FLAB studied have high cell surface hydrophobicity and fulfil next selection criterion for their use as probiotics. Symbionts of A. mellifera showed also auto- and co-aggregation capacities regarded as valuable features for biofilm formation and inhibition of pathogens adhesion to the bee gut cells. Biofilm-development ability is a desired characteristic of probiotic lactic acid bacteria. As indicated by quantitative crystal violet-stained microplate assay and confocal laser scanning microscopy imaging, all studied A. mellifera gut isolates exhibit a biofilm positive phenotype. Moreover, it was also documented, on honey bees kept in cages, that supplementation of A. mellifera sucrose diet with FLAB decreases mortality and improves significantly longevity of honey bees. Presented research showed that A. mellifera FLAB symbionts are good candidates for application as probiotics.

Development of Polythiourethane/ZnO-Based Anti-Fouling Materials and Evaluation of the Adhesion of Staphylococcus aureus and Candida glabrata Using Single-Cell Force Spectroscopy

The attachment of bacteria and other microbes to natural and artificial surfaces leads to the development of biofilms, which can further cause nosocomial infections. Thus, an important field of research is the development of new materials capable of preventing the initial adhesion of pathogenic microorganisms. In this work, novel polymer/particle composite materials, based on a polythiourethane (PTU) matrix and either spherical (s-ZnO) or tetrapodal (t-ZnO) shaped ZnO fillers, were developed and characterized with respect to their mechanical, chemical and surface properties. To then evaluate their potential as anti-fouling surfaces, the adhesion of two different pathogenic microorganism species, Staphylococcus aureus and Candida glabrata, was studied using atomic force microscopy (AFM). Our results show that the adhesion of both S. aureus and C. glabrata to PTU and PTU/ZnO is decreased compared to a model surface polydimethylsiloxane (PDMS). It was furthermore found that the amount of both s-ZnO and t-ZnO filler had a direct influence on the adhesion of S. aureus, as increasing amounts of ZnO particles resulted in reduced adhesion of the cells. For both microorganisms, material composites with 5 wt.% of t-ZnO particles showed the greatest potential for anti-fouling with significantly decreased adhesion of cells. Altogether, both pathogens exhibit a reduced capacity to adhere to the newly developed nanomaterials used in this study, thus showing their potential for bio-medical applications.

Molecular evaluation of quorum quenching potential of vanillic acid against Yersinia enterocolitica through transcriptomic and in silico analysis

Introduction. Yersinia enterocolitica is one of the leading food-borne entero-pathogens causing various illnesses ranging from gastroenteritis to systemic infections. Quorum sensing (QS) is one of the prime mechanisms that control the virulence in Y. enterocolitica .

Hypothesis/Gap Statement. Vanillic acid inhibits the quorum sensing and other virulence factors related to Y. enterocolitica . It has been evaluated by transcriptomic and Insilico analysis. Therefore, it can be a prospective agent to develop a therapeutic combination against Y. enterocolitica .

Aim. The present study is focused on screening natural anti-quorum-sensing agents against Y. enterocolitica . The effect of selected active principle on various virulence factors was evaluated.

Methodology. In total, 12 phytochemicals were screened by swarming assay. MATH assay, EPS and surfactant production assay, SEM analysis, antibiotic and blood sensitivity assay were performed to demonstrate the anti-virulence activity. Further, RNA sequencing and molecular docking studies were carried out to substantiate the anti-QS activity.

Results. Vanillic acid (VA) has exhibited significant motility inhibition, thus indicating the anti-QS activity with MQIC of 400 µg ml−1 without altering the cell viability. It has also inhibited the violacein production in Chromobacterium violaceum ATCC 12472, which further confirms the anti-QS activity. VA has inhibited 16 % of cell-surface hydrophobicity (CSH), 52 % of EPS production and 60 % of surfactant production. Moreover, it has increased the sensitivity of Y. enterocolitica towards antibiotics. It has also made the cells upto 91 % more vulnerable towards human immune cells. The transcriptomic analysis by RNA sequencing revealed the down regulation of genes related to motility, virulence, chemotaxis, siderophores and drug resistance. VA treatment has also positively regulated the expression of several stress response genes. In furtherance, the anti-QS potential of VA has been validated with QS regulatory protein YenR by in silico molecular simulation and docking study.

Conclusion. The present study is possibly the first attempt to demonstrate the anti-QS and anti-pathogenic potential of VA against Y. enterocolitica by transcriptomic and in silico analysis. It also deciphers that VA can be a promising lead to develop biopreservative and therapeutic regimens to treat Y. enterocolitica infections.

O-Methylation of the Glycopeptidolipid Acyl Chain Defines Surface Hydrophobicity of Mycobacterium abscessus and Macrophage Invasion

Mycobacterium abscessus, an emerging pathogen responsible for severe lung infections in cystic fibrosis patients, displays either smooth (S) or rough (R) morphotypes. The S-to-R transition is associated with reduced levels of glycopeptidolipid (GPL) production and is correlated with increased pathogenicity in animal and human hosts. While the structure of GPL is well established, its biosynthetic pathway is incomplete. In addition, the biological functions of the distinct structural parts of this complex lipid remain elusive. Herein, the fmt gene encoding a putative O-methyltransferase was deleted in the M. abscessus S variant. Subsequent biochemical and structural analyses demonstrated that methoxylation of the fatty acyl chain of GPL was abrogated in the Δfmt mutant, and this defect was rescued upon complementation with a functional fmt gene. In contrast, the introduction of fmt derivatives mutated at residues essential for methyltransferase activity failed to complement GPL defects, indicating that fmt encodes an O-methyltransferase. Unexpectedly, phenotypic analyses showed that Δfmt was more hydrophilic than its parental progenitor, as demonstrated by hexadecane-aqueous buffer partitioning and atomic force microscopy experiments with hydrophobic probes. Importantly, the invasion rate of THP-1 macrophages by Δfmt was reduced by 50% when compared to the wild-type strain. Together, these results indicate that Fmt O-methylates the lipid moiety of GPL and plays a substantial role in conditioning the surface hydrophobicity of M. abscessus as well as in the early steps of the interaction between the bacilli and macrophages.

5-Hydroxymethylfurfural inhibits Acinetobacter baumannii biofilms: an in vitro study

The present study was aimed to investigate the antibiofilm activity of 5-hydroxymethylfurfural against Acinetobacter baumanni and Vellar estuary isolates v3 (Acinetobacter nosocomialis). The biofilm inhibitory concentration (BIC) of 5HMF against A. baumannii and v3 (A. nosocomialis) was found to be 100 µg/ml) exhibited non-bactericidal concentration-dependent antibiofilm activities against Acinetobacter species. The present study found that 5HMF treatment is very effective in the initial stage of A. baumannii biofilms and it significantly disrupted the mature biofilms. Moreover, 5HMF treatment inhibited the extracellular polymeric substances (EPS), including polysaccharides and proteins production. Results from gene expression and in vitro assays further demonstrated the 5HMF treatment downregulated the expression of bfmR, bap, csuA/B, ompA and katE virulence genes, which consistently affects biofilm formation and its mediated virulence property. The present study suggests that 5HMF unveil its antibiofilm activity by interfering initial biofilm formation and suppressing the virulence regulator genes in A. baumannii. Further studies are required to explore the 5HMF mode of action responsible for the antibiofilm activity.

Heterologous expression of the Salmonella enterica serovar Paratyphi A stk fimbrial operon suggests a potential for repeat sequence-mediated low-frequency phase variation

Fimbriae mediate adhesion of Salmonella enterica organisms to the intestinal epithelium, which is an essential step in the pathogenesis process preceding invasion and/or systemic spread. In addition, Salmonella fimbrial genes transcripts were detected in the blood samples from Salmonella infected human patients, which supports the proposal that fimbriae play a role in invasive Salmonella infections. In this study, BlastN-based interrogation of the NCBI bacterial genome database and PCR investigation of Salmonella serovars have shown that the S. Paratyphi A stkF gene and/or the whole stk fimbrial gene cluster is present in about ~30% of S. enterica serovars investigated up to date. Furthermore, bioinformatics and phenotypic characterization have revealed that the stk fimbrial operon belongs to the chaperone/usher-γ4- fimbrial clade and that it encodes a mannose-sensitive hemagglutinating fimbrial structure. The latter trait is typical of type 1 fimbriae, in which fimbrial phase variation is common. The observed intragenic, 26 bp tandem repeat triplication event in stkF would suggest that slipped-strand mispairing and/or recombination within a signature stkF-borne tandem repeat motif as a likely mechanism for a form of low-frequency phase switching at the translational level leading to allelic OFF forms, hence the inability of production and/or absence of fimbriae by EM-examination on E. coli HB101/pUCstk-stkF_OFFv2. The in vitro profile of marked anti-StkF-mediated opsonophagocytosis and complement-mediated killing activity observed coupled with the mice immunogenicity profile strongly supports further investigation of StkF as a potential Salmonella vaccine candidate.

The hydrophobicity of enterobacteria and their co-aggregation with Enterococcus faecalis isolated from Serbian cheese

In this paper, we investigated the hydrophobicity, ability to adhere to solvents and the pig epithelium and co-aggregation of members of family Enterobacteriaceae and Enterococcus faecalis KGPMF 49. The bacteria used in this study were isolated from traditionally made autochthonous cheese from Southeastern Serbia (Sokobanja). The percentage of adhered bacteria was different in three solvents (chloroform, ethyl acetate and xylene). The highest percentage was detected in the presence of chloroform, and the lowest percentage was detected in the presence of xylene (chloroform < ethyl acetate < xylene). A different degree of co-aggregation of enterobacteria with E. faecalis KGPMF 49 was observed. Klebsiella ornithinolytica KGPMF 8 demonstrated the highest percentage of co-aggregation with E. faecalis KGPMF49 (32.29%). Klebsiella pneumoniae KGPMF 13, K. ornithinolytica KGPMF 9 and Serratia marcescens biogp 1 KGPMF 19 were found to have the ability to adhere to the pig epithelium, whereas Escherichia coli KGPMF 22 showed no such ability. The ability to co-aggregate with other species and the ability to adhere to the pig epithelium are very important characteristics of the isolated bacteria.

Vancomycin-loaded electrospun polycaprolactone/nano-hydroxyapatite membrane for the treatment of blood infections

Nowadays, because of the resistance of bacteria to antibiotics, researchers are trying to make new antibiotics or sometimes even bring them back into the treatment cycle so that they could eliminate the bacteria's resistance. On the other hand, the use of nanofibers has become widespread in many fields for their unique properties and convenient design. The present study focuses on the production of hydrophobic nanofibers to absorb the bacteria and their toxins from the bloodstream that contains the infection. Many bacterial surfaces have hydrophobic surfactant properties due to hydrophobic surface protein. According to the principle of binding two hydrophobic molecules to each other in an aqueous medium, the nanofibers are designed to physically absorb the bacteria. The use of antibiotics in the study can remove some unattached bacteria. In addition, using nanofiber manufacturing techniques can reduce the resistance of bacteria to antibiotics. The construction of the desired membrane can be used in subsequent studies as a replacement membrane for dialysis filters.

Fast chemical force microscopy demonstrates that glycopeptidolipids define nanodomains of varying hydrophobicity on mycobacteria

Mycobacterium abscessus is an emerging multidrug-resistant bacterial pathogen causing severe lung infections in cystic fibrosis patients. A remarkable trait of this mycobacterial species is its ability to form morphologically smooth (S) and rough (R) colonies. The S-to-R transition is caused by the loss of glycopeptidolipids (GPLs) in the outer layer of the cell envelope and correlates with an increase in cording and virulence. Despite the physiological and medical importance of this morphological transition, whether it involves changes in cell surface properties remains unknown. Herein, we combine recently developed quantitative imaging (QI) atomic force microscopy (AFM) with hydrophobic tips to quantitatively map the surface structure and hydrophobicity of M. abscessus at high spatiotemporal resolution, and to assess how these properties are modulated by the S-to-R transition and by treatment with an inhibitor of the mycolic acid transporter MmpL3. We discover that loss of GPLs leads to major modifications in surface hydrophobicity, without any apparent change in cell surface ultrastructure. While R bacilli are homogeneously hydrophobic, S bacilli feature unusual variations of nanoscale hydrophobic properties. These previously undescribed cell surface nanodomains are likely to play critical roles in bacterial adhesion, aggregation, phenotypic heterogeneity and transmission, and in turn in virulence and pathogenicity. Our study also suggests that MmpL3 inhibitors show promise in nanomedicine as chemotherapeutic agents to interfere with the highly hydrophobic nature of the mycobacterial cell wall. The advantages of QI-AFM with hydrophobic tips are the ability to map chemical and structural properties simultaneously and at high resolution, applicable to a wide range of biosystems.

Physical and biological properties of blend-electrospun polycaprolactone/chitosan-based wound dressings loaded with N-decyl-N, N-dimethyl-1-decanaminium chloride: An in vitro and in vivo study

Dual-pump electrospinning of antibacterial N-decyl-N, N-dimethyl-1-decanaminium-chloride (DDAC)-loaded polycaprolactone (PCL) nanofibers, and chitosan (CS)/polyethylene-oxide (PEO)-based wound dressings with hydrophilic and hydrophobic properties to eliminate and absorb pathogenic bacteria from wound surface besides antibacterial action and to support wound healing and accelerate its process. Physicochemical properties of the prepared nanofibrous mat as well as antibacterial, cytotoxicity, and cell compatibility were studied. The full-thickness excisional wound healing properties up to 3 weeks using hematoxylin and eosin and Masson-trichrome staining were investigated. Addition of DDAC to CS/PEO-PCL mats decreased the diameter of the nanofibers, which is a crucial property for wound healing as large surface area per volume ratio of nanofibers, in addition to proper cell adhesion, increases loading of DDAC in mats and leads to increased cell viability and eliminating Gram-positive bacteria at in vitro studies. In vivo studies showed DDAC-loaded CS/PEO-PCL mats increased epithelialization and angiogenesis and decreased the inflammation according to histological results. We demonstrated that hydrophobic PCL/DDAC mats, besides antibacterial properties of DDAC, absorbed and eliminated the hydrophobic pathological microorganisms, whereas the hydrophilic nanofibers consisted of CS/PEO, increased the cell adhesion and proliferation due to positive charge of CS. Finally, we were able to increase the wound healing quality by using multifunctional wound dressing. CS/PEO-PCL containing 8 wt % of DDAC nanofibrous mats is promising as a wound dressing for wound management due to the favorable interactions between the pathogenic bacteria and PCL/CS-based wound dressing.

Synthesis of multisegmented block copolymer by Friedel–Crafts hydroxyalkylation polymerization

Friedel–Crafts (FC) polycondensation of 1,4-dimethoxybenzene with 4-substituted benzaldehyde species was used to prepare telechelic oligomers and high-molar-mass multisegmented block copolymers.

Yersinia pseudotuberculosis-derived adhesins

Around fifteen surface components referred to adhesins have been identified in Yersinia pseudotuberculosis combining primarily microbiological, molecular and genetic, as well as immunochemical and biophysical methods. Y. pseudotuberculosis-derived adhesins vary in structure and chemical composition but they are mainly presented by protein molecules. Some of them were shown to participate not only in adhesive but in other pathogen-related physiological functions in the host-parasite interplay. Adhesins can mediate bacterial adhesion to eukaryotic cell either directly or via the extracellular matrix components. These adhesion molecules are encoded by chromosomal DNA excepting YadA protein which gene is located in the calcium-dependence plasmid pYV common for pathogenic yersisniae. An optimum temperature for adhesin biosynthesis is located close to the body temperature of warm-blooded animals; however, at low temperature only invasin InvA, full-length smooth lipopolysaccharide and porin OmpF are produced in Y. pseudotuberculosis. Several adhesins (Psa, InvA) can be expressed at low pH (corresponds to intracellular content), thereby defining pathogenic yersiniae as facultative intracellular parasites. Three human Yersinia genus pathogens differ by ability to produce adhesins. Y. pseudotuberculosis adherence to host cells or extracellular matrix components is determined by a cumulative adhesion-based activity, which expression depends on chemical composition and physicochemical environmental conditions. It’s proposed that at the initial stage of infectious process adherence of Y. pseudotuberculosis to intestinal epithelium is mediated by InvA protein and “smooth” LPS form. These adhesins are produced in bacterial cells at low (lower than 30°С) temperature occurring in environment from which a pathogen invades into the host. At later stages of pathogenesis, after penetrating through intestinal epithelium, bacterial cells produce other adhesins, which promote survival and dissemination primarily into the mesenteric lymph nodes and, possibly, liver and spleen. At later stages of pathogenesis, after penetrating through intestinal epithelium, bacterial cells produce other adhesins, which promote survival and dissemination primarily into the mesenteric lymph nodes and, perhaps, liver and spleen. Qualitative and quantitative spectrum of Y. pseudotuberculosis adhesins is determined by environmental parameters (intercellular space, intracellular content within the diverse eukaryotic cells).

Anti quorum sensing and anti virulence activity of tannic acid and it's potential to breach resistance in Salmonella enterica Typhi / Paratyphi A clinical isolates

Salmonella enterica Typhi and Paratyphi A are food borne pathogens causing typhoid, which is one of the most important food borne disease in the developing world. S. Typhi and S. Paratyphi A are of much concern as multi drug resistance has been on the rise. The current study is aimed to screen phytochemicals for anti quorum sensing (QS) activity against S. Typhi and S. Paratyphi A. Upon screening with swarming assay, tannic acid (TA) showed highest anti-QS activity with minimal concentration of 400μg/ml. The anti-QS activity of TA was confirmed with C. violaceum ATCC 12,472. TA showed 38-43% and 35-50% of inhibition in cell surface hydrophobicity and EPS production respectively. Through FTIR analysis, it has been observed that EPS of treated cells has a considerable change in protein and peptide. TA has also exhibited drastic reduction in the surfactant production as high as 85-90%. Blood sensitivity and antibiotic sensitivity assay revealed that TA significantly sensitizes the S. Typhi and S. Paratyphi A cells to immune components in human blood and antibiotics. It has reduced the resistance of S. Typhi and S. Paratyphi A cells against amikacin, ampicillin, ciprofloxacin, azithromycin, chloramphenicol and gentamycin, thus revitalized the usage of these antibiotics against drug resistant S. Typhi and S. Paratyphi A infections. The consistency of anti-QS potential of TA was further evaluated and established with another eight clinical isolates of S. Typhi and S. Paratyphi A. Thus TA has been proved as a promising anti QS agent that can be developed as a therapeutic combination against S. Typhi and S. Paratyphi A.

Deciphering the intrinsic properties of fungal proteases in optimizing phytopathogenic interaction

Phytopathogenic fungi secrete a wide range of enzymes to penetrate and colonize host tissues. Of them protease activity is reported to increase disease aggressiveness in the plant. With the aim to explore the reason of the higher infection potential of proteases, we have compared several genomic and proteomic attributes among different hydrolytic enzymes coded by five pathogenic fungal species which are the potent infectious agents of plant. Categorizing the enzymes into four major groups, namely protease, lipase, amylase and cell-wall degraders, we observed that proteases are evolutionary more conserved, have higher expression levels, contain more hydrophobic buried residues, short linear motifs and post-translational modified (PTM) sites than the other three groups of enzymes. Again, comparing these features of protease between pathogenic and non-pathogenic Aspergillus sps, we have hypothesized that protein structural properties could play significant roles in imposing infection potency to the fungal proteases.

New insights on yeast and filamentous fungus adhesion in a natural co-immobilization system: proposed advances and applications in wine industry

Fungi possess extraordinary strength in attachment to biotic and abiotic surfaces. This review focuses on adhesion mechanisms of yeast and filamentous fungi and the proposed combination of the adhesive forces of both organisms in an immobilization system called yeast biocapsules, whereby Saccharomyces cerevisiae cells are attached to the hyphae of Penicillium chrysogenum. The natural adherent properties of each organism, one multicellular and another unicellular, allow yeast to be fixated securely on the filamentous fungi and complete alcoholic fermentation. Following alcoholic fermentation, the hyphae become an inert support for yeast cells while maintaining shape and integrity. Biocapsules have been used successfully in both wine and bioethanol production. Investigation of the potential genes involved in fungal-yeast fusion suggests that natural hydrophobic interactions of both organisms play a major role. Analysis of the possible mechanisms involved in fungus and yeast adhesion, future perspectives on improving yeast immobilization, and proposed applications of the biocapsules are explored.

What is the Best Micro and Macro Dental Implant Topography?

Implant surface micro and macro topography plays a key role in early osseointegration. The physicochemical features of the implant surface (ie, chemical composition, hydrophobicity/hydrophilicity and roughness) influence the deposition of extracellular matrix proteins, the precipitation of bone mineral, and the stimulation of cells. Modification of the implant topography provides better primary stability and faster osseointegration, allowing for immediate placement or immediate loading. Randomized clinical trials are warranted to compare the response of osseointegration with various implant micro and macro surface topographies in people with various local or systemic risk factors.

Temporary Wettability Tuning of PCL/PDMS Micro Pattern Using the Plasma Treatments

Surface wettability plays an important role in determining the function of a wound dressing. Dressings with hydrophobic surfaces are suitable for bacterial adsorption, however, a hydrophilic surface is needed to improve cell attachment for most anchorage-dependent cell types. Furthermore, the hydrophobicity/hydrophilicity of the surface can be used to direct cellular processes such as cell initial attachment, adhesion, and migration during wound healing. Thus, a surface with an ability to switch their surface wettability improves the practicality of the dressing. In this study, we propose a temporary surface wettability tuning for surface patterning utilizing plasma treatment. Polycaprolactone (PCL) and polydimethylsiloxane (PDMS) surfaces were treated with tetrafluoromethane (CF₄), sulphur hexafluoride (SF₆), and oxygen (O₂) plasma, and the effects on the surface wettability, roughness, and chemical composition were investigated. Based on the contact angle measurement, CF₄ plasma altered surface wettability of PCL and PDMS films to hydrophobic and hydrophilic, respectively. After CF₄ treatment, better attachment of primary mouse embryonic fibroblast cell (3T3) was observed on the treated PDMS surface. Embedding PCL into PDMS generated a hydrophobic-hydrophilic pattern mixture surface, which offers great potential in the tissue engineering field such as cell patterning and guidance.

Petroleum Hydrocarbon-Degrading Bacteria for the Remediation of Oil Pollution Under Aerobic Conditions: A Perspective Analysis

With the sharp increase in population and modernization of society, environmental pollution resulting from petroleum hydrocarbons has increased, resulting in an urgent need for remediation. Petroleum hydrocarbon-degrading bacteria are ubiquitous in nature and can utilize these compounds as sources of carbon and energy. Bacteria displaying such capabilities are often exploited for the bioremediation of petroleum oil-contaminated environments. Recently, microbial remediation technology has developed rapidly and achieved major gains. However, this technology is not omnipotent. It is affected by many environmental factors that hinder its practical application, limiting the large-scale application of the technology. This paper provides an overview of the recent literature referring to the usage of bacteria as biodegraders, discusses barriers regarding the implementation of this microbial technology, and provides suggestions for further developments.

Effective anti-adhesives of uropathogenic Escherichia coli

Urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (UPEC) are among the most common infectious diseases in humans. Due to their frequent occurrence in the community and nosocomial settings, as well as the development of resistance to the commonly prescribed antimicrobial agents, an enormous financial burden is placed on healthcare systems around the world. Therefore, novel approaches to the prevention and treatment of UTIs are needed. Although UPEC may harbour a plethora of virulence factors, type I fimbriae and P pili are two of the most studied adhesive organelles, since the attachment to host cells in the urinary tract is a crucial step towards infection. Design of receptor analogues that competitively bind to UPEC surface adhesins placed at the top of pili organelles led to the development of anti-adhesive drugs that are increasingly recognized as important and promising alternatives to antibiotic treatment of UTIs.

Exogenous N-acyl homoserine lactones facilitate microbial adhesion of high ammonia nitrogen wastewater on biocarrier surfaces

Startup of biofilm process triggered by initial adhesion of bacteria is difficult in high ammonia nitrogen wastewater treatment. In this study, the influence of two commonly used N-acyl homoserine lactones (AHLs), N-Hexanoyl-l-homoserine lactone (C6-HSL) and N-Octanoyl-l-homoserine lactone (C8-HSL), on the adhesion of soluble macromolecules and bacteria in four types of high ammonia nitrogen wastewater to surfaces of model biocarriers (i.e. polystyrene, polyamide and polyethylene terephthalate) was investigated by using a quartz crystal microbalance with dissipation (QCM-D) monitoring technology. Results showed that the adhesion was enhanced by the addition of exogenous AHLs and there was more microbial retention attributed by C8-HSL. Greater deposition amount was generally found on PS and better enhanced performances of the adhesion were found on PA surface. Furthermore, viscoelastic film formed under synchronous high-low salinity and organic content and dominant bacteria of real wastewater determined the role of exogenous AHLs. The method of adding moderate amount of exogenous AHLs into bioreactors has important implications for accelerating the startup process treating high ammonia nitrogen wastewater by biofilm process.

An in vitro and in silico identification of antibiofilm small molecules from seawater metaclone SWMC166 against Vibrio cholerae O1

This study aimed to determine the antibiofilm activity of seawater microbes against Vibrio cholerae (VCO1) through functional metagenomics approach. A metagenomic library was constructed from Palk Bay seawater and the library was screened to identify the biofilm inhibitory metaclone. Metaclone SWMC166 (harbouring ∼30 kb metagenomic insert) was found to exhibit antibiofilm activity against VCO1. The biofilm inhibitory potential of partially purified ethyl acetate extract of SWMC166 (EA166) was further evaluated through microscopic studies and biochemical assays. Further, EA166 treated VCO1 divulged up-regulation of genes involved in high cell density-mediated quorum sensing (QS) pathway which was analysed by real-time PCR. In order to identify the genes of interest (within ∼30 kb insert), subcloning was performed through shotgun approach. Small molecules from positive subclones SC5 and SC8 were identified through HRLC-MS analysis. Resulted small molecules were docked against QS receptors of V. cholerae to identify the bioactive metabolites. Docking studies revealed that totally seven metabolites were able to interact with QS receptors that can possibly trigger the QS cascade and sequentially inhibit the biofilm formation and virulence factors of VCO1.

Deficient Lipid A Remodeling by the arnB Gene Promotes Biofilm Formation in Antimicrobial Peptide Susceptible Pseudomonas aeruginosa

Multidrug resistant bacteria possess various mechanisms that can sense environmental stresses such as antibiotics and antimicrobial peptides and rapidly respond to defend themselves. Two known defense strategies are biofilm formation and lipopolysaccharide (LPS) modification. Though LPS modifications are observed in biofilm-embedded bacteria, their effect on biofilm formation is unknown. Using biochemical and biophysical methods coupled with confocal microscopy, atomic force microscopy, and transmission electron microscopy, we show that biofilm formation is promoted in a Pseudomonas aeruginosa PAO1 strain with a loss of function mutation in the arnB gene. This loss of function prevents the addition of the positively charged sugar 4-amino-4-deoxy-l-arabinose to lipid A of LPS under restrictive magnesium conditions. The data reveal that the arnB mutant, which is susceptible to antimicrobial peptides, forms a biofilm that is more robust than that of the wild type. This is in line with the observations that the arnB mutant exhibits outer surface properties such as hydrophobicity and net negative charge that promote the formation of biofilms. Moreover, when grown under Mg²⁺ limitation, both the wild type and the arnB mutant exhibited a reduction in the level of membrane-bound polysaccharides. The data suggest that the loss of polysaccharides exposes the membrane and alters its biophysical properties, which in turn leads to more biofilm formation. In summary, we show for the first time that blocking a specific lipid A modification promotes biofilm formation, suggesting a trade-off between LPS remodeling and resistance mechanisms of biofilm formation.

Capsular Polysaccharide Interferes with Biofilm Formation by Pasteurella multocida Serogroup A

Pasteurella multocida is an important multihost animal and zoonotic pathogen that is capable of causing respiratory and multisystemic diseases, bacteremia, and bite wound infections. The glycosaminoglycan capsule of P. multocida is an essential virulence factor that protects the bacterium from host defenses. However, chronic infections (such as swine atrophic rhinitis and the carrier state in birds and other animals) may be associated with biofilm formation, which has not been characterized in P. multocida. Biofilm formation by clinical isolates was inversely related to capsule production and was confirmed with capsule-deficient mutants of highly encapsulated strains. Capsule-deficient mutants formed biofilms with a larger biomass that was thicker and smoother than the biofilm of encapsulated strains. Passage of a highly encapsulated, poor-biofilm-forming strain under conditions that favored biofilm formation resulted in the production of less capsular polysaccharide and a more robust biofilm, as did addition of hyaluronidase to the growth medium of all of the strains tested. The matrix material of the biofilm was composed predominately of a glycogen exopolysaccharide (EPS), as determined by gas chromatography-mass spectrometry, nuclear magnetic resonance, and enzymatic digestion. However, a putative glycogen synthesis locus was not differentially regulated when the bacteria were grown as a biofilm or planktonically, as determined by quantitative reverse transcriptase PCR. Therefore, the negatively charged capsule may interfere with biofilm formation by blocking adherence to a surface or by preventing the EPS matrix from encasing large numbers of bacterial cells. This is the first detailed description of biofilm formation and a glycogen EPS by P. multocida.

Pasteurella multocida is an important pathogen responsible for severe infections in food animals, domestic and wild birds, pet animals, and humans. P. multocida was first isolated by Louis Pasteur in 1880 and has been studied for over 130 years. However, aspects of its lifecycle have remained unknown. Although formation of a biofilm by P. multocida has been proposed, this report is the first to characterize biofilm formation by P. multocida. Of particular interest is that the biofilm matrix material contained a newly reported amylose-like glycogen as the exopolysaccharide component and that production of capsular polysaccharide (CPS) was inversely related to biofilm formation. However, even highly mucoid, poor-biofilm-forming strains could form abundant biofilms by loss of CPS or following in vitro passage under biofilm growth conditions. Therefore, the carrier state or subclinical chronic infections with P. multocida may result from CPS downregulation with concomitant enhanced biofilm formation.

An approach to study ultrastructural changes and adaptive strategies displayed by Acinetobacter guillouiae SFC 500-1A under simultaneous Cr(VI) and phenol treatment

Acinetobacter guillouiae SFC 500-1A, a native bacterial strain isolated from tannery sediments, is able to simultaneously remove high concentrations of Cr(VI) and phenol. In this complementary study, high-resolution microscopy techniques, such as atomic force microscopy (AFM) and transmission electron microscopy (TEM), were used to improve our understanding of some bacterial adaptive mechanisms that enhance their ability to survive. AFM contributed in gaining insight into changes in bacterial size and morphology. It allowed the unambiguous identification of pollutant-induced cellular disturbances and the visualization of bacterial cells with depth sensitivity. TEM analysis revealed that Cr(VI) produced changes mainly at the intracellular level, whereas phenol produced alterations at the membrane level. This strain tended to form more extensive biofilms after phenol treatment, which was consistent with microscopy images and the production of exopolysaccharides (EPSs). In addition, other exopolymeric substances (DNA, proteins) significantly increased under Cr(VI) and phenol treatment. These exopolymers are important for biofilm formation playing a key role in bacterial aggregate stability, being especially useful for bioremediation of environmental pollutants. This study yields the first direct evidences of a range of different changes in A. guillouiae SFC 500-1A which seems to be adaptive strategies to survive in stressful conditions.