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1.
Soft Matter ; 17(35): 8185-8194, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34525168

RESUMO

Because bacterial adhesion to surfaces is associated with infections and biofilm growth, it has been a longstanding goal to develop coatings that minimize biomolecular adsorption and eliminate bacteria adhesion. We demonstrate that, even on carefully-engineered non-bioadhesive coatings such as polyethylene glycol (PEG) layers that prevent biomolecule adsorption and cell adhesion, depletion interactions from non-adsorbing polymer in solution (such as 10 K PEG or 100 K PEO) can cause adhesion and retention of Escherichia coli cells, defeating the antifouling functionality of the coating. The cells are immobilized and remain viable on the timescale of the study, at least up to 45 minutes. When the polymer solution is replaced by buffer, cells rapidly escape from the surface, consistent with expectations for the reversibility of depletion attractions. The dissolved polymer additionally causes cells to aggregate in solution and aggregates rapidly dissociate to singlets upon tenfold dilution in buffer, also consistent with depletion. Hydrodynamic forces can substantially reduce the adhesion of aggregates on surfaces in conditions where single cells adhere via depletion. The findings reported here suggest that because bacteria thrive in polymer-rich environments both in vivo and in situ, depletion interactions may make it impossible to avoid bacterial retention on surfaces.


Assuntos
Aderência Bacteriana , Biofilmes , Adsorção , Bactérias , Polietilenoglicóis , Propriedades de Superfície
2.
Gene ; 803: 145890, 2021 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-34375634

RESUMO

Escherichia coli Nissle 1917 (EcN) is an efficient probiotic strain extensively used worldwide because of its several health benefits. Adhesion to the intestinal cells is one of the prerequisites for a probiotic strain. To identify the genes essential for the adhesion of EcN on the intestinal cells, we utilized a quantitative genetic footprinting approach called transposon insertion sequencing (INSeq). A transposon insertion mutant library of EcN comprising of ~17,000 mutants was used to screen the adherence to the intestinal epithelial cells, Caco-2. The transposon insertion sites were identified from the input and output population by employing next-generation sequencing using the Ion torrent platform. Based on the relative abundance of reads in the input and output pools, we identified 113 candidate genes that are essential for the fitness of EcN during the adhesion and colonization on the Caco-2 cells. Functional categorization revealed that these fitness genes are associated with carbohydrate transport and metabolism, cell wall/membrane/envelope biogenesis, post-translational modification, stress response, motility and adhesion, and signal transduction. To further validate the genes identified in our INSeq analysis, we constructed individual knock-out mutants in five genes (cyclic di-GMP phosphodiesterase (gmp), hda, uidC, leuO, and hypothetical protein-coding gene). We investigated their ability to adhere to Caco-2 cells. Evaluation of these mutants showed reduced adhesion on Caco-2 cells, confirming their role in adhesion. Understanding the functions of these genes may provide novel insights into molecular regulation during colonization of probiotic bacteria to the intestinal cells, and useful to develop designer probiotic strains.


Assuntos
Proteínas de Escherichia coli/genética , Escherichia coli/fisiologia , Mutagênese Insercional , Análise de Sequência de DNA/métodos , Aderência Bacteriana , Células CACO-2 , Elementos de DNA Transponíveis , Escherichia coli/genética , Aptidão Genética , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Probióticos
3.
J Microbiol ; 59(9): 854-860, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34382147

RESUMO

Extraintestinal pathogenic Escherichia coli (ExPEC) is an important zoonotic pathogen that places severe burdens on public health and animal husbandry. There are many pathogenic factors in E. coli. The type VI secretion system (T6SS) is a nano-microbial weapon that can assemble quickly and inject toxic effectors into recipient cells when danger is encountered. T6SSs are encoded in the genomes of approximately 25% of sequenced Gram-negative bacteria. When these bacteria come into contact with eukaryotic cells or prokaryotic microbes, the T6SS assembles and secretes associated effectors. In the porcine ExPEC strain PCN033, we identified four classic rearrangement hotspot (Rhs) genes. We determined the functions of the four Rhs proteins through mutant construction and protein expression. Animal infection experiments showed that the Δrhs-1CT, Δrhs-2CT, Δrhs-3CT, and Δrhs-4CT caused a significant decrease in the multiplication ability of PCN033 in vivo. Cell infection experiments showed that the Rhs protein is involved in anti-phagocytosis activities and bacterial adhesion and invasion abilities. The results of this study demonstrated that rhs1, rhs3, and rh4 plays an important role in the interaction between PCN033 and host cell. Rhs2 has contribution to cell and mice infection. This study helps to elucidate the pathogenic mechanism governing PCN033 and may help to establish a foundation for further research seeking to identify potential T6SS effectors.


Assuntos
Infecções por Escherichia coli/veterinária , Proteínas de Escherichia coli/metabolismo , Doenças dos Suínos/microbiologia , Animais , Aderência Bacteriana , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/genética , Escherichia coli Extraintestinal Patogênica/genética , Escherichia coli Extraintestinal Patogênica/metabolismo , Feminino , Intestinos/microbiologia , Camundongos , Família Multigênica , Suínos
4.
Int J Mol Sci ; 22(16)2021 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-34445157

RESUMO

Proteus mirabilis-mediated CAUTIs are usually initiated by the adherence of bacteria to a urinary catheter surface. In this paper, three isolates of different origin and exhibiting different adhesion abilities were investigated in search of any changes in lipidome components which might contribute to P. mirabilis adhesion to catheters. Using GC-MS and LC-MS/MS techniques, 21 fatty acids and 27 phospholipids were identified in the examined cells. The comparison of the profiles of phospholipids and fatty acids obtained for catheter-attached cells and planktonic cells of the pathogens indicated C11:0 and PE 37:2 levels as values which could be related to P. mirabilis adhesion to a catheter, as well as cis C16:1, PE 32:0, PE 33:0, PE 38:2, PG 33:1, PG 34:0, PE 30:1, PE 32:1 and PG 30:2 levels as values which could be associated with cell hydrophobicity. Based on DiBAC4 (3) fluorescence intensity and an affinity to p-xylene, it was found that the inner membrane depolarization, as well as strong cell-surface hydrophobicity, were important for P. mirabilis adhesion to a silicone catheter. A generalized polarization of Laurdan showed lower values for P. mirabilis cells attached to the catheter surface than for planktonic cells, suggesting lower packing density of membrane components of the adherent cells compared with tightly packed, stiffened membranes of the planktonic cells. Taken together, these data indicate that high surface hydrophobicity, fluidization and depolarization of P. mirabilis cell membranes enable colonization of a silicone urinary catheter surface.


Assuntos
Ácidos Graxos/metabolismo , Fosfolipídeos/metabolismo , Infecções por Proteus/microbiologia , Proteus mirabilis/fisiologia , Cateteres Urinários/microbiologia , Aderência Bacteriana , Humanos
5.
Molecules ; 26(16)2021 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-34443480

RESUMO

Within this study, new materials were synthesized and characterized based on polysiloxane modified with different ratios of N-acetyl-l-cysteine (NAC) and crosslinked via UV-assisted thiol-ene addition, in order to obtain efficient membranes able to resist bacterial adherence and biofilm formation. These membranes were subjected to in vitro testing for microbial adherence against S. pneumoniae using standardized tests. WISTAR rats were implanted for 4 weeks with crosslinked siloxane samples without and with NAC. A set of physical characterization methods was employed to assess the chemical structure and morphological aspects of the new synthetized materials before and after contact with the microbiological medium.


Assuntos
Antibacterianos/química , Materiais Revestidos Biocompatíveis/química , Implantes Cocleares/microbiologia , Otite/tratamento farmacológico , Polímeros/química , Siloxanas/química , Acetilcisteína/química , Acetilcisteína/farmacologia , Acetilcisteína/uso terapêutico , Animais , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Aderência Bacteriana/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/farmacologia , Materiais Revestidos Biocompatíveis/uso terapêutico , Implantes Cocleares/efeitos adversos , Polímeros/farmacologia , Polímeros/uso terapêutico , Ratos Wistar , Siloxanas/farmacologia , Siloxanas/uso terapêutico , Streptococcus pneumoniae/efeitos dos fármacos , Compostos de Sulfidrila/química , Propriedades de Superfície
6.
Int J Mol Sci ; 22(16)2021 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-34445234

RESUMO

Abiotrophia defectiva is a nutritionally variant streptococci that is found in the oral cavity, and it is an etiologic agent of infective endocarditis. We have previously reported the binding activity of A. defectiva to fibronectin and to human umbilical vein endothelial cells (HUVECs). However, the contribution of some adhesion factors on the binding properties has not been well delineated. In this study, we identified DnaK, a chaperon protein, as being one of the binding molecules of A. defectiva to fibronectin. Recombinant DnaK (rDnaK) bound immobilized fibronectin in a concentration-dependent manner, and anti-DnaK antiserum reduced the binding activity of A. defectiva with both fibronectin and HUVECs. Furthermore, DnaK were observed on the cell surfaces via immune-electroscopic analysis with anti-DnaK antiserum. Expression of IL-8, CCL2, ICAM-1, and VCAM-1 was upregulated with the A. defectiva rDnaK treatment in HUVECs. Furthermore, TNF-α secretion of THP-1 macrophages was also upregulated with the rDnaK. We observed these upregulations in rDnaK treated with polymyxin B, but not in the heat-treated rDnaK. The findings show that A. defectiva DnaK functions not only as an adhesin to HUVECs via the binding to fibronectin but also as a proinflammatory agent in the pathogenicity to cause infective endocarditis.


Assuntos
Abiotrophia/metabolismo , Aderência Bacteriana , Proteínas de Bactérias/metabolismo , Fibronectinas/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Células Endoteliais da Veia Umbilical Humana/metabolismo , Abiotrophia/genética , Proteínas de Bactérias/genética , Proteínas de Choque Térmico HSP70/genética , Células Endoteliais da Veia Umbilical Humana/microbiologia , Humanos , Inflamação/genética , Inflamação/metabolismo , Inflamação/microbiologia
7.
J Med Microbiol ; 70(8)2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34338626

RESUMO

Introduction. Biofilm formation is a major virulence factor associated with Staphylococcus aureus infections. However, the influence of plasma proteins on biofilm formation of clinical isolates in vitro remains unclear.Hypotheses. We hypothesized that coating surfaces with plasma proteins might induce biofilm formation by S. aureus of different clonal lineages.Aim. To evaluate biofilm production by clinical S. aureus isolates of different clonal lineages isolated in Rio de Janeiro hospitals and investigated the presence of biofilm-associated genes.Methodology. This study assessed biofilm production of 60 S. aureus isolates in polystyrene microtitre plates with and without fibrinogen or fibronectin. The biochemical composition of the biofilm matrices was determined and the biofilm formation on fibrinogen-coated surfaces was also evaluated by confocal laser scanning microscopy. The presence of biofilm-related genes was detected by PCR, and the typing and functionality of agr operon was also evaluated.Results. Most of the isolates (45 %) were weak biofilm producers or non-producers. However, most of them presented a significant increase in biofilm production on plates covered with plasma proteins. There was no significant difference in biofilm formation between methicillin-resistant and -susceptible S. aureus isolates, or between different clonal lineages, except for ST30-IV (weak producers) and ST239-III (strong producers). The fnbB gene was associated with higher biofilm production.Conclusion. An increase in biofilm production in the presence of plasma proteins highlights the importance of investigating biofilm formation by S. aureus clinical isolates under different conditions since this virulence factor contributes to persistent infections and increased resistance to antimicrobials.


Assuntos
Biofilmes/crescimento & desenvolvimento , Fibrinogênio , Fibronectinas , Staphylococcus aureus Resistente à Meticilina/patogenicidade , Staphylococcus aureus/patogenicidade , Adesinas Bacterianas/genética , Aderência Bacteriana/genética , Proteínas de Bactérias/genética , Genes Bacterianos , Genótipo , Humanos , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Staphylococcus aureus Resistente à Meticilina/fisiologia , Óperon , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/genética , Staphylococcus aureus/isolamento & purificação , Staphylococcus aureus/fisiologia , Transativadores/genética
8.
BMC Genomics ; 22(1): 550, 2021 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-34275445

RESUMO

BACKGROUND: Fibrillar adhesins are long multidomain proteins that form filamentous structures at the cell surface of bacteria. They are an important yet understudied class of proteins composed of adhesive and stalk domains that mediate interactions of bacteria with their environment. This study aims to characterize fibrillar adhesins in a wide range of bacterial phyla and to identify new fibrillar adhesin-like proteins to improve our understanding of host-bacteria interactions. RESULTS: Through careful literature and computational searches, we identified 82 stalk and 27 adhesive domain families in fibrillar adhesins. Based on the presence of these domains in the UniProt Reference Proteomes database, we identified and analysed 3,542 fibrillar adhesin-like proteins across species of the most common bacterial phyla. We further enumerate the adhesive and stalk domain combinations found in nature and demonstrate that fibrillar adhesins have complex and variable domain architectures, which differ across species. By analysing the domain architecture of fibrillar adhesins, we show that in Gram positive bacteria, adhesive domains are mostly positioned at the N-terminus and cell surface anchors at the C-terminus of the protein, while their positions are more variable in Gram negative bacteria. We provide an open repository of fibrillar adhesin-like proteins and domains to enable further studies of this class of bacterial surface proteins. CONCLUSION: This study provides a domain-based characterization of fibrillar adhesins and demonstrates that they are widely found in species across the main bacterial phyla. We have discovered numerous novel fibrillar adhesins and improved our understanding of pathogenic adhesion and invasion mechanisms.


Assuntos
Adesinas Bacterianas , Proteínas de Bactérias , Adesinas Bacterianas/genética , Bactérias/genética , Aderência Bacteriana , Proteínas de Bactérias/genética , Bactérias Gram-Positivas , Proteínas de Membrana
9.
J Biol Regul Homeost Agents ; 35(2 Suppl. 1): 205-210, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34281318

RESUMO

After oral surgery, bacterial adhesion to suture can cause surgical site infections and delay wound healing. Microbial adherence to the suture is influenced by its physical configuration and chemical structure. The aim of this study was to compare in vivo the bacterial adhesion to two suture materials used in oral surgery: silk and monofilament expanded polytetrafluoethilene (e-PTFE). After sinus lift surgery, 15 flaps were sutured with silk (nonabsorbable, organic, braided, 4.0) and 15 were sutured with e-PTFE (nonabsorbable, synthetic, monofilament, 4.0). Seven days after surgery, bacterial adherence, in terms of percentage of the surface covered, was evaluated for each suture material by scanning electron microscope (SEM). Onto silk suture, plaque consisted of a few cocci and a higher proportion of rods and filamentous-shaped bacteria, with some mineralized plaque. Onto e-PTFE speciments, only small colonies of a few cocci or no bacteria were observed, with empty spaces between the colonies and no plaque mineralization. The surface covered by bacteria on e-PTFE specimens was significantly lower than that of silk sutures. (22.1% ±4.96% vs 54.3% ± 7.9%; P =0.0001). The results of the present study suggest that multifilament structure of silk favours a greater bacterial adherence, proliferation, and persistence, so monofilament and e- PTFE suture should be preferred in oral surgery.


Assuntos
Seda , Suturas , Bactérias , Aderência Bacteriana , Humanos , Infecção da Ferida Cirúrgica
10.
NPJ Biofilms Microbiomes ; 7(1): 58, 2021 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-34244520

RESUMO

The low viability during gastrointestinal transit and poor mucoadhesion considerably limits the effectiveness of Ligilactobacillus salivarius Li01 (Li01) in regulating gut microbiota and alleviating inflammatory bowel disease (IBD). In this study, a delivery system was designed through layer-by-layer (LbL) encapsulating a single Li01cell with chitosan and alginate. The layers were strengthened by cross-linking to form a firm and mucoadhesive shell (~10 nm thickness) covering the bacterial cell. The LbL Li01 displayed improved viability under simulated gastrointestinal conditions and mucoadhesive function. Almost no cells could be detected among the free Li01 after 2 h incubation in digestive fluids, while for LbL Li01, the total reduction was around 3 log CFU/mL and the viable number of cells remained above 6 log CFU/mL. Besides, a 5-fold increase in the value of rupture length and a two-fold increase in the number of peaks were found in the (bacteria-mucin) adhesion curves of LbL Li01, compared to those of free Li01. Oral administration with LbL Li01 on colitis mice facilitated intestinal barrier recovery and restoration of the gut microbiota. The improved functionality of Li01 by LbL encapsulation could increase the potential for the probiotic to be used in clinical applications to treat IBD; this should be explored in future studies.


Assuntos
Técnicas Bacteriológicas , Lactobacillus/fisiologia , Animais , Aderência Bacteriana , Biomarcadores , Linhagem Celular , Colite/etiologia , Colite/metabolismo , Colite/patologia , Citocinas/metabolismo , Modelos Animais de Doenças , Suscetibilidade a Doenças , Humanos , Mediadores da Inflamação , Doenças Inflamatórias Intestinais/etiologia , Doenças Inflamatórias Intestinais/metabolismo , Camundongos , Viabilidade Microbiana , Probióticos/administração & dosagem
11.
Int J Mol Sci ; 22(12)2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-34208782

RESUMO

This paper concerns the physicochemical properties of chitosan/phenolic acid thin films irradiated by ultraviolet radiation with wavelengths between 200 and 290 nm (UVC) light. We investigated the preparation and characterization of thin films based on chitosan (CTS) with tannic (TA), caffeic (CA) and ferulic acid (FA) addition as potential food-packaging materials. Such materials were then exposed to the UVC light (254 nm) for 1 and 2 h to perform the sterilization process. Different properties of thin films before and after irradiation were determined by various methods such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimeter (DSC), mechanical properties and by the surface free energy determination. Moreover, the antimicrobial activity of the films and their potential to reduce the risk of contamination was assessed. The results showed that the phenolic acid improving properties of chitosan-based films, short UVC radiation may be used as sterilization method for those films, and also that the addition of ferulic acid obtains effective antimicrobial activity, which have great benefit for food packing applications.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Quitosana/química , Hidroxibenzoatos/química , Raios Ultravioleta , Aderência Bacteriana/efeitos dos fármacos , Varredura Diferencial de Calorimetria , Fenômenos Químicos , Fenômenos Mecânicos , Testes de Sensibilidade Microbiana , Microscopia de Força Atômica , Espectroscopia de Infravermelho com Transformada de Fourier
12.
Nat Commun ; 12(1): 4547, 2021 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-34315900

RESUMO

The human pathogen Neisseria meningitidis can cause meningitis and fatal systemic disease. The bacteria colonize blood vessels and rapidly cause vascular damage, despite a neutrophil-rich inflammatory infiltrate. Here, we use a humanized mouse model to show that vascular colonization leads to the recruitment of neutrophils, which partially reduce bacterial burden and vascular damage. This partial effect is due to the ability of bacteria to colonize capillaries, venules and arterioles, as observed in human samples. In venules, potent neutrophil recruitment allows efficient bacterial phagocytosis. In contrast, in infected capillaries and arterioles, adhesion molecules such as E-Selectin are not expressed on the endothelium, and intravascular neutrophil recruitment is minimal. Our results indicate that the colonization of capillaries and arterioles by N. meningitidis creates an intravascular niche that precludes the action of neutrophils, resulting in immune escape and progression of the infection.


Assuntos
Arteríolas/microbiologia , Derme/irrigação sanguínea , Neisseria meningitidis/crescimento & desenvolvimento , Neutrófilos/microbiologia , Adulto , Animais , Arteríolas/patologia , Aderência Bacteriana , Capilares/microbiologia , Capilares/patologia , Moléculas de Adesão Celular/metabolismo , Contagem de Colônia Microbiana , Selectina E/metabolismo , Endotélio Vascular/microbiologia , Endotélio Vascular/patologia , Feminino , Fímbrias Bacterianas/metabolismo , Xenoenxertos , Humanos , Inflamação/patologia , Masculino , Infecções Meningocócicas/microbiologia , Infecções Meningocócicas/patologia , Camundongos SCID , Pessoa de Meia-Idade , Infiltração de Neutrófilos , Fagocitose , Fatores de Tempo , Regulação para Cima , Adulto Jovem
13.
ACS Appl Mater Interfaces ; 13(27): 32205-32216, 2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34225456

RESUMO

Biofouling remains as a persistent problem impeding the applications of membranes for water and wastewater treatment. Green anti-biofouling of membranes made of natural and environmentally friendly materials and methods is a promising strategy to tackle this problem. Herein, we have developed a functionalized PVDF membrane with stimuli-responsive lysozyme nanocapsules (NCP). These nanocapsules can responsively release lysozyme according to environmental stimuli (pH and redox) induced by bacteria. Results showed that (i) the surface of the functionalized membrane with NCP had enhanced hydrophilicity, reduced roughness, and negative charge, (ii) a remarkable reduction of adsorption of proteins, polysaccharides, and bacteria was achieved by the functionalized membrane, and (iii) the colony forming unit (CFU) of bacteria on a membrane surface was reduced more than 80% within 24 h of contact. In addition, the NCP membrane showed excellent anti-biofouling activity regarding the bacterial viability being 12.5 and 8.3% on the membrane after filtration with 108 CFU mL-1 Escherichia coli and Staphylococcus aureus solution as feed, respectively. The coating layer and assembled nanocapsules endowed the membrane with improved lysozyme stability, anti-adhesion performance, and antibacterial activity. Stimuli-responsive lysozyme nanocapsule engineered microfiltration membranes show great potential for anti-biofouling in future practical application.


Assuntos
Incrustação Biológica/prevenção & controle , Engenharia , Filtração , Membranas Artificiais , Microtecnologia/métodos , Muramidase/química , Muramidase/farmacologia , Antibacterianos/química , Antibacterianos/farmacologia , Aderência Bacteriana/efeitos dos fármacos , Cápsulas , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Viabilidade Microbiana/efeitos dos fármacos , Nanoestruturas/química , Oxirredução , Propriedades de Superfície
14.
Arch Microbiol ; 203(7): 4221-4231, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34091701

RESUMO

The Escherichia coli (E. coli) nirC gene encodes a nitrite transporter, which involved in transporting toxic nitrite (NO2-) from the environment into the bacteria. Although the deletion of nirC gene could cause changes in motility, adhesion in the previous study, and the virulence involved in the specified mechanism for pathogenic E. coli remains to be known. In the present work, we aimed to evaluate the role of NirC in a serotype O2:K1:H7 avian pathogenic Escherichia coli (APEC) strain. For this purpose, we generated a NirC-deficient mutant of APEC XM strain and examined its biological characteristics. The nirC gene deletion mutant enhanced ability of motility, decreased in biofilm formation, and it markedly reduced ability to adhere mouse brain microvascular endothelial cell b.End3 cells. For understanding its mechanism, sequentially we detected and found the stress regulator rpoS and its downstream genes csrA were up-regulated in NirC-deficient mutant while diguanylate cyclase gene dgcT was down-regulated. By high-performance liquid chromatography (HPLC) experiment, we demonstrated the concentration of intracellular 3',5'-cyclic diguanosine monophosphate (c-di-GMP) significantly decrease in nirC gene deletion mutant. Taken data together, we may make a conclusion with a possible signal pathway clue, due to NirC mutation, environmental NO2- accumulation leads to nitrite stress and inactivates c-di-GMP synthesis by stimulating the stress regulator RpoS, resulting in changes of biological characteristics.


Assuntos
Proteínas de Transporte de Ânions/metabolismo , Proteínas de Escherichia coli/metabolismo , Animais , Proteínas de Transporte de Ânions/genética , Aderência Bacteriana/genética , Biofilmes , Linhagem Celular , Escherichia coli/genética , Escherichia coli/metabolismo , Infecções por Escherichia coli , Proteínas de Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Camundongos , Mutação , Proteínas de Ligação a RNA/genética , Proteínas Repressoras/genética , Virulência/genética
15.
Langmuir ; 37(25): 7720-7729, 2021 06 29.
Artigo em Inglês | MEDLINE | ID: mdl-34125547

RESUMO

Motivated by observations of cell orientation at biofilm-substrate interfaces and reports that cell orientation and adhesion play important roles in biofilm evolution and function, we investigated the influence of surface chemistry on the orientation of Escherichia coli cells captured from flow onto surfaces that were cationic, hydrophobic, or anionic. We characterized the initial orientations of nonmotile cells captured from gentle shear relative to the surface and flow directions. The broad distribution of captured cell orientations observed on cationic surfaces suggests that rapid electrostatic attractions of cells to oppositely charged surfaces preserve the instantaneous orientations of cells as they rotate in the near-surface shearing flow. By contrast, on hydrophobic and anionic surfaces, cells were oriented slightly more in the plane of the surface and in the flow direction compared with that on the cationic surface. This suggests slower development of adhesion at hydrophobic and anionic surfaces, allowing cells to tip toward the surface as they adhere. Once cells were captured, the flow was increased by 20-fold. Cells did not reorient substantially on the cationic surface, suggesting a strong cell-surface bonding. By contrast, on hydrophobic and anionic surfaces, increased shear forced cells to tip toward the surface and align in the flow direction, a process that was reversible upon reducing the shear. These findings suggest mechanisms by which surface chemistry may play a role in the evolving structure and function of microbial communities.


Assuntos
Aderência Bacteriana , Escherichia coli , Biofilmes , Interações Hidrofóbicas e Hidrofílicas , Propriedades de Superfície
16.
ACS Appl Mater Interfaces ; 13(24): 27774-27783, 2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34115463

RESUMO

Medical device-associated infections are an ongoing problem. Once an implant is infected, bacteria create a complex community on the surface known as a biofilm, protecting the bacterial cells against antibiotics and the immune system. To prevent biofilm formation, several coatings have been engineered to hinder bacterial adhesion or viability. In recent years, liquid-infused surfaces (LISs) have been shown to be effective in repelling bacteria due to the presence of a tethered liquid interface. However, local lubricant loss or temporary local displacement can lead to bacteria penetrating the lubrication layer, which can then attach to the surface, proliferate, and form a biofilm. Biofilm formation on biomedical devices can subsequently disrupt the chemistry tethering the slippery liquid interface, causing the LIS coating to fail completely. To address this concern, we developed a "fail-proof" multifunctional coating through the combination of a LIS with tethered antibiotics. The coatings were tested on a medical-grade stainless steel using contact angle, sliding angle, and Fourier transform infrared spectroscopy. The results confirm the presence of antibiotics while maintaining a stable and slippery liquid interface. The antibiotic liquid-infused surface significantly reduced biofilm formation (97% reduction compared to the control) and was tested against two strains of Staphylococcus aureus, including a methicillin-resistant strain. We also demonstrated that antibiotics remain active and reduce bacteria proliferation after subsequent coating modifications. This multifunctional approach can be applied to other biomaterials and provide not only a fail-safe but a fail-proof strategy for preventing bacteria-associated infections.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Aderência Bacteriana/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/química , Fluorcarbonetos/química , Glicopeptídeos/farmacologia , Humanos , Lubrificantes/química , Staphylococcus aureus Resistente à Meticilina/fisiologia , Testes de Sensibilidade Microbiana , Aço Inoxidável/química
17.
Int J Mol Sci ; 22(10)2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-34063332

RESUMO

Artificial sweeteners (AS) are synthetic sugar substitutes that are commonly consumed in the diet. Recent studies have indicated considerable health risks which links the consumption of AS with metabolic derangements and gut microbiota perturbations. Despite these studies, there is still limited data on how AS impacts the commensal microbiota to cause pathogenicity. The present study sought to investigate the role of commonly consumed AS on gut bacterial pathogenicity and gut epithelium-microbiota interactions, using models of microbiota (Escherichia coli NCTC10418 and Enterococcus faecalis ATCC19433) and the intestinal epithelium (Caco-2 cells). Model gut bacteria were exposed to different concentrations of the AS saccharin, sucralose, and aspartame, and their pathogenicity and changes in interactions with Caco-2 cells were measured using in vitro studies. Findings show that sweeteners differentially increase the ability of bacteria to form a biofilm. Co-culture with human intestinal epithelial cells shows an increase in the ability of model gut bacteria to adhere to, invade and kill the host epithelium. The pan-sweet taste inhibitor, zinc sulphate, effectively blocked these negative impacts. Since AS consumption in the diet continues to increase, understanding how this food additive affects gut microbiota and how these damaging effects can be ameliorated is vital.


Assuntos
Enterococcus faecalis/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Microbioma Gastrointestinal/efeitos dos fármacos , Edulcorantes/farmacologia , Aspartame/administração & dosagem , Aspartame/farmacologia , Aderência Bacteriana/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Células CACO-2 , Relação Dose-Resposta a Droga , Enterococcus faecalis/patogenicidade , Escherichia coli/patogenicidade , Microbioma Gastrointestinal/fisiologia , Hemólise/efeitos dos fármacos , Humanos , Sacarina/administração & dosagem , Sacarina/farmacologia , Sacarose/administração & dosagem , Sacarose/análogos & derivados , Sacarose/farmacologia , Edulcorantes/administração & dosagem
18.
Nano Lett ; 21(12): 5105-5115, 2021 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-34086465

RESUMO

For bacterial adhesion and biofilm formation, a thorough understanding of the mechanism and effective modulating is lacking due to the complex extracellular electron transfer (EET) at bacteria-surface interfaces. Here, we explore the adhesion behavior of a model electroactive bacteria under various metabolic conditions by an integrated electrochemical single-cell force microscopy system. A nonlinear model between bacterial adhesion force and electric field intensity is established, which provides a theoretical foundation for precise tuning of bacterial adhesion strength by the surface potential and the direction and flux of electron flow. In particular, based on quantitative analyses with equivalent charge distribution modeling and wormlike chain numerical simulations, it is demonstrated that the chain conformation and unfolding events of outer membrane appendages are dominantly impacted by the dynamic bacterial EET processes. This reveals how the anisotropy of bacterial conductive structure can translate into the desired adhesion behavior in different scenarios.


Assuntos
Aderência Bacteriana , Elétrons , Fenômenos Fisiológicos Bacterianos , Biofilmes , Condutividade Elétrica , Transporte de Elétrons
19.
Food Res Int ; 146: 110471, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34119244

RESUMO

The importance of various Lactobacillus strains and milk components, such as the milk fat globule membrane, has been studied from various perspectives and proven to have a positive role in human health. On one end, lactic acid bacteria produce metabolites with direct effect in the immune system, changes of pH in the gut, and antagonistic substances for pathogenic bacteria as well as competition. On the other end, the milk fat globule membrane improves gastrointestinal status by promoting cell proliferation, epithelial tight junction patterns, and development of intestinal epithelial cells. Interaction between beneficial bacteria and milk fat is a natural occurring phenomenon in dairy products; however, it has not been fully characterized. In this work, we studied the effect of milk phospholipids in the adhesion of Lactobacillus to mucus-producing Caco-2/Goblet cell co-cultures and found that treatment with phospholipids produced bacterial cells with increased surface electronegativity, which was correlated with increased bacterial cells adhered to the intestinal model. Moreover, we utilized an original means of characterizing the adhesion using quartz crystal microbalance. All strains studied, experienced modification of adhesion either physicochemical or kinetic parameters studied. Furthermore, by imaging bacterial cells by electron microscopy, we identified that some strains, such as L. acidophillus and L. casei, metabolized MPL, which improved their adhesion to hydrophilic surfaces such as gold. We identified another group of bacteria, such as L. delbrueckii and L. plantarum, that, instead of metabolizing MPL, kept the phospholipids bound irreversibly to the surface of the cell envelope thus decreasing their adherence to gold surfaces. One of the most important aspects of probiotic lactic acid bacteria -besides survival in the stomach-is the colonization and extended resident time in the intestine to effectively change the gut microbiome. We found that bacterial treatment with milk phospholipids enhances adhesion to intestinal models and will in turn, increase the residence time with the concomitant benefits to the consumer.


Assuntos
Lactobacillus , Fosfolipídeos , Aderência Bacteriana , Células CACO-2 , Glicolipídeos , Glicoproteínas , Células Caliciformes , Humanos , Gotículas Lipídicas , Muco
20.
Molecules ; 26(10)2021 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-34070126

RESUMO

Antimicrobial resistance is one of the major public health threats at the global level, urging the search for new antimicrobial molecules. The fluorene nucleus is a component of different bioactive compounds, exhibiting diverse pharmacological actions. The present work describes the synthesis, chemical structure elucidation, and bioactivity of new O-aryl-carbamoyl-oxymino-fluorene derivatives and the contribution of iron oxide nanoparticles to enhance the desired biological activity. The antimicrobial activity assessed against three bacterial and fungal strains, in suspension and biofilm growth state, using a quantitative assay, revealed that the nature of substituents on the aryl moiety are determinant for both the spectrum and intensity of the inhibitory effect. The electron-withdrawing inductive effect of chlorine atoms enhanced the activity against planktonic and adhered Staphylococcus aureus, while the +I effect of the methyl group enhanced the anti-fungal activity against Candida albicans strain. The magnetite nanoparticles have substantially improved the antimicrobial activity of the new compounds against planktonic microorganisms. The obtained compounds, as well as the magnetic core@shell nanostructures loaded with these compounds have a promising potential for the development of novel antimicrobial strategies.


Assuntos
Anti-Infecciosos/farmacologia , Biofilmes/efeitos dos fármacos , Fluorenos/farmacologia , Nanopartículas Magnéticas de Óxido de Ferro/química , Bactérias/efeitos dos fármacos , Aderência Bacteriana/efeitos dos fármacos , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Fluorenos/química , Fungos/efeitos dos fármacos , Nanopartículas Magnéticas de Óxido de Ferro/ultraestrutura , Magnetometria , Testes de Sensibilidade Microbiana , Plâncton/efeitos dos fármacos , Espectroscopia de Prótons por Ressonância Magnética , Espectroscopia de Infravermelho com Transformada de Fourier
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