RESUMO
Ralstonia pseudosolanacearum GMI1000 (Rpso GMI1000) is a soil-borne vascular phytopathogen that infects host plants through the root system causing wilting disease in a wide range of agro-economic interest crops, producing economical losses. Several features contribute to the full bacterial virulence. In this work we study the participation of light, an important environmental factor, in the regulation of the physiological attributes and infectivity of Rpso GMI1000. In silico analysis of the Rpso genome revealed the presence of a Rsp0254 gene, which encodes a putative blue light LOV-type photoreceptor. We constructed a mutant strain of Rpso lacking the LOV protein and found that the loss of this protein and light, influenced characteristics involved in the pathogenicity process such as motility, adhesion and the biofilms development, which allows the successful host plant colonization, rendering bacterial wilt. This protein could be involved in the adaptive responses to environmental changes. We demonstrated that light sensing and the LOV protein, would be used as a location signal in the host plant, to regulate the expression of several virulence factors, in a time and tissue dependent way. Consequently, bacteria could use an external signal and Rpsolov gene to know their location within plant tissue during the colonization process.
Assuntos
Proteínas de Bactérias/genética , Interações Hospedeiro-Patógeno/fisiologia , Ralstonia/fisiologia , Solanum lycopersicum/microbiologia , Aderência Bacteriana/fisiologia , Proteínas de Bactérias/metabolismo , Biofilmes/crescimento & desenvolvimento , Regulação Bacteriana da Expressão Gênica , Luz , Polissacarídeos Bacterianos/genética , Polissacarídeos Bacterianos/metabolismo , Ralstonia/patogenicidadeRESUMO
The estimation of growth or inactivation of bacterial population in fruits during preservation and storage provides useful information for the improvement of the safety of fresh-cut fruits and vegetables. This paper addressed the attachment to the surface and the growth in the flesh of apple fruits of four bacterial cultures (Escherichia coli, Bacillus cereus, Staphylococcus aureus and Pseudomonas aeruginosa). The growth of the bacterial cultures in apple flesh was monitored at particular time intervals, and Gompertz parameters, i.e. maximum number of bacteria (Pm), the maximum growth rate of bacteria rp,m, and lag time tl, were used to determine the growth kinetics. After the immersion, the highest number of P. aeruginosa and the lowest number of B. cereus adhered to the apples. After washing and swabbing, E. coli was reduced from the surface of apples to the highest extent (by 3.34 log cfu g-1), while the number of B. cereus was reduced to the lowest extent (1.66 log cfu g-1). Fitted curves of the Gompertz model corresponded quite well to the measured values of the number of microorganisms with R2 = 0.92-0.98. The values of the standard error (0.17-0.37) and extremely low p values of the Fischer test (p < 0.0001) indicated strict dependence between the model predicted and the maximum population density. The predicted values of the maximum number of microorganisms (Pm) correspond almost exactly to the actual values. A similar conclusion can be drawn for the maximum growth rate of microorganisms (rp,m), with the measured value being slightly higher than predicted values.
Assuntos
Bactérias/crescimento & desenvolvimento , Aderência Bacteriana/fisiologia , Malus/microbiologia , Modelos Teóricos , Anti-Infecciosos/análise , Anti-Infecciosos/farmacologia , Antioxidantes/análise , Antioxidantes/metabolismo , Bactérias/classificação , Bactérias/efeitos dos fármacos , Aderência Bacteriana/efeitos dos fármacos , Contagem de Colônia Microbiana , Frutas/microbiologia , Cinética , Malus/química , Viabilidade Microbiana/efeitos dos fármacosRESUMO
The adhesion of pathogenic bacteria to host cells and the extracellular matrix (ECM) is considered an important step in the pathogenesis of microorganisms. It has been described that Leptospira spp. bind to multiple receptors on host cells and to the ECM to initiate infection. Most studies of Leptospira adherence described until now have focused on the in vitro attachment of recombinant L. interrogans proteins to ECM components. These putative adhesins may be involved in the colonization of the host, contributing to the bacterial invasion process. Certainly, in vitro cell adhesion studies have contributed to the elucidation of leptospiral pathogenesis mechanisms. Here, we describe a cell adhesion assay that can be used for studying the interactions between putative leptospiral adhesins and host components.
Assuntos
Aderência Bacteriana/fisiologia , Proteínas de Bactérias/metabolismo , Adesão Celular/fisiologia , Interações Hospedeiro-Patógeno/fisiologia , Leptospira/patogenicidade , Leptospirose/microbiologia , Adesinas Bacterianas/metabolismo , Matriz Extracelular/metabolismo , Humanos , Leptospira/metabolismoRESUMO
Metal corrosion is a major global concern in many economic sectors. The degradation of metal surfaces is responsible for losses in values that account for about 3% of gross domestic product (GDP) only in the US. Parts of all corrosion processes described in different environments are present mainly in marine environments. The marine environment is characterized as favoring the corrosion processes of several metallic alloys, damaging structures used in the construction of ships, ports, oil pipelines, and others. Despite chemical corrosion being the most frequently described in these environments, studies show the participation of microorganisms in direct corrosion processes or in the acceleration/influence of the corrosive action, through the formation of complex biofilms. These structures create favorable conditions for microorganisms to degrade metal surfaces, causing damage known as pitting and crevices. Currently, diverse technicians are employed in biocorrosion research, e.g. electronic microscopy, and DNA sequencing. These techniques have clarified the dynamic process of the formation of biofilm structures, allowing understanding of the succession of different species during the evolution of the structure. Improving the understanding of how this interaction between biofilm and metallic surface occurs will enable better evaluation of strategies to avoid or decelerate the degradation of metallic structures in marine environments.
Assuntos
Biofilmes/crescimento & desenvolvimento , Água do Mar/microbiologia , Aço/química , Ligas/química , Bactérias/metabolismo , Aderência Bacteriana/fisiologia , Fenômenos Fisiológicos Bacterianos , Corrosão , Eletroquímica , Metais/química , Propriedades de SuperfícieRESUMO
Little is known about Salmonella biofilm assembly, making the prevention of the disease a challenge in the poultry production chain. The objective of the present study was then to evaluate biofilm formation from different serotypes of Salmonella spp. in both polystyrene plates and eggshells. Salmonella Gallinarum and S. Minnesota were both classified as producers of biofilms of moderate intensity. Interestingly, S. Gallinarum produces biofilm even though being a serotype without flagellum and not having the lux gene in its genome, suggesting that there might be other important structures and genes associated with biofilm formation. Regarding Enteritidis, Typhimurium, Typhimurium variant, and Heidelberg serotypes, despite having high counts, BFI (Biofilm Formation Index) showed low biofilm production, probably due to the scarcity of extracellular matrix produced by such strains. A turkey eggshell model was then used for S. Enteritidis and S. Heidelberg biofilm formation. The results from the microbial count and scanning electron microscopy showed that Salmonella serotypes were also able to generate biofilm in eggshells, suggesting the presence of biofilms in poultry producing farms, a main concern for the poultry production industry.
Assuntos
Biofilmes/crescimento & desenvolvimento , Aves Domésticas/microbiologia , Salmonelose Animal/microbiologia , Salmonella/classificação , Salmonella/crescimento & desenvolvimento , Animais , Aderência Bacteriana/fisiologia , Casca de Ovo/microbiologia , Fazendas , Microbiologia de AlimentosRESUMO
Conditions of the acrylic resin (AR) surface, such as roughness, can promote a favourable environment for the adhesion of micro-organisms, even on the surface of ocular prostheses. This study evaluated the influence of photopolymerized glaze application on the roughness of ARs and adhesion of Staphylococcus aureus and Staphylococcus epidermidis on ocular AR surfaces submitted to accelerated ageing. Two hundred and eighty-eight samples of white colour (N1) and colourless ARs were distributed in eight groups (n = 9), based on surface treatments (glaze or ARs submitted to only a final polishing), accelerated ageing (before and after) and periods of microbial growth (24- and 48-h). The roughness average (Ra) and total height of roughness profile (Rt) values were greater for the groups with glaze and increased for all groups after ageing. The microbial adhesion among the groups with and without glaze did not present a statistically significant difference. The ageing did not statistically affect the adhesion of Staph. epidermidis, but affected the adhesion of Staph. aureus, which presented an increase after 24 h of growth on only N1 AR with glaze. These results demonstrate that the glaze did not contribute to adhesion of Staph. aureus and Staph. epidermidis, which are responsible for most ocular prosthetic infections. SIGNIFICANCE AND IMPACT OF THE STUDY: Some recent evidence suggested that the surface finish of ocular prostheses influences the accumulation of deposits that can affect the interaction with pathogenic bacteria, increasing the probability of infections. In addition, surface deterioration over time can increase the roughness and, consequently, biofilm formation. Thus, a better understanding of the influence of surface finish on bacterial adhesion becomes extremely important. In this study, we tested a glaze for surface polishing compared to mechanical polishing, before and after ageing. The results suggest that the glaze did not contribute to microbial adhesion and might be useful in preventing possible prosthetic infections.
Assuntos
Resinas Acrílicas/química , Aderência Bacteriana/fisiologia , Olho Artificial/microbiologia , Staphylococcus aureus/metabolismo , Staphylococcus epidermidis/metabolismo , Propriedades de SuperfícieRESUMO
OBJECTIVES: The objective of this study was to evaluate the ability of Lactobacillus curvatus CRL705, CRL1532, and CRL1533 and Lactobacillus sakei CRL1613 to survive under simulated gastrointestinal conditions. Moreover, a microencapsulation approach was proposed to improve gastrointestinal survival. Finally, experiments were performed to demonstrate that Lactobacillus spp. can modulate the ability of Listeria monocytogenes FBUNT to adhere to and invade Caco-2 cells. RESULTS: Lactobacillus strains were encapsulated in alginate beads to enhance the survival of bacteria under in vitro gastrointestinal conditions. All strains hydrolyzed bile salts using chenodeoxycholic acid as a substrate and adhered to Caco-2 cells. Cell-free supernatants (CFSs) showed antimicrobial activity against L. monocytogenes as demonstrated by agar diffusion assays. The average percentages of L. monocytogenes adhesion decreased from 67.74 to 41.75 and 38.7% in the presence of 50 and 90% (v/v), respectively, for all CFSs tested. The highest concentrations of CFSs completely inhibited the L. monocytogenes invasion of Caco-2 cells. CONCLUSIONS: The studied Lactobacillus strains have protective effects against the adhesion and invasion of L. monocytogenes FBUNT. Alginate encapsulation of these bacteria improved gastrointestinal tolerance such that they could be further studied as potential probiotics against intestinal pathogenic bacteria.
Assuntos
Aderência Bacteriana/fisiologia , Lactobacillus/fisiologia , Listeria monocytogenes/patogenicidade , Interações Microbianas/fisiologia , Probióticos/farmacologia , Aderência Bacteriana/efeitos dos fármacos , Ácidos e Sais Biliares/metabolismo , Células CACO-2 , Humanos , Lactobacillus/metabolismo , Listeria monocytogenes/metabolismo , Listeria monocytogenes/fisiologiaRESUMO
This study aimed to assess the capability of 97 epidemic S. enterica strains belonging to 18 serovars to form biofilm. Five strains characterized as strong biofilm-producers, belonging to distinct serovars (S. Enteritidis 132, S. Infantis 176, S. Typhimurium 177, S. Heidelberg 281 and S. Corvallis 297) were assayed for adhesion/biofilm formation on stainless steel surfaces. The experiments were conducted in different combinations of NaCl (0, 2, 4, 5, 6, 8 and 10% w/v), pH (4, 5, 6 and 7) and temperatures (8⯰C, 12⯰C, 20⯰C and 35⯰C). Only adhesion was assumed to occur when S. enterica counts were ≥3 and <5â¯logâ¯CFU/cm2, whereas biofilm formation was defined as when the counts were ≥5â¯logâ¯CFU/cm2. The binary responses were used to develop models to predict the probability of adhesion/biofilm formation on stainless steel surfaces by five strains belonging to different S. enterica serovars. A total of 99% (96/97) of the tested S. enterica strains were characterized as biofilm-producers in the microtiter plate assays. The ability to form biofilm varied (Pâ¯<â¯0.05) within and among the different serovars. Among the biofilm-producers, 21% (20/96), 45% (43/96), and 35% (34/96) were weak, moderate and strong biofilm-producers, respectively. The capability for adhesion/biofilm formation on stainless steel surfaces under the experimental conditions studied varied among the strains studied, and distinct secondary models were obtained to describe the behavior of the five S. enterica tested. All strains showed adhesion at pHâ¯4 up to 4% of NaCl and at 20⯰C and 35⯰C. The probability of adhesion decreased when NaCl concentrations were >8% and at 8⯰C, as well as in pH valuesâ¯≤â¯5 and NaCl concentrationsâ¯>â¯6%, for all tested strains. At pHâ¯7 and 6, biofilm formation for S. Enteritidis, S. Infantis, S. Typhimurium, S. Heidelberg was observed up to 6% of NaCl at 35⯰C and 20⯰C. The predicted boundaries for adhesion were pH valuesâ¯<â¯5 and NaClâ¯≥â¯4% and at temperatures <20⯰C. For biofilm formation, the predicted boundaries were pH valuesâ¯<â¯5 and NaCl concentrationsâ¯≥â¯2% and at temperatures <20⯰C for all strains. The secondary models obtained describe the variability in boundaries of adhesion and biofilm formation on stainless steel by five strains belonging to different S. enterica serovars. The boundary models can be used to predict adhesion and biofilm formation ability on stainless steel by S. enterica as affected by pH, NaCl and temperature.
Assuntos
Aderência Bacteriana/fisiologia , Biofilmes , Salmonella enterica/fisiologia , Cloreto de Sódio , Aço Inoxidável , Temperatura , Aderência Bacteriana/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Salmonella enterica/classificação , Salmonella enterica/efeitos dos fármacos , Sorogrupo , Cloreto de Sódio/farmacologia , Especificidade da EspécieRESUMO
Staphylococcus aureus has become the most common opportunistic microorganism related to nosocomial infections due to the bacteria capacity to form biofilms on biomedical devices and implants. Since bacterial adhesion is the first step in this pathogenesis, it is evident that inhibiting such a process will reduce the opportunity for bacterial colonization on the devices. This work is aimed at optimizing a surface biofunctionalization strategy to inhibit the adhesion of S. aureus on solid substrates. The first part of the work deals with the albumin adsorption-desorption process, studied by a factorial design of experiments to explore a wide range of experimental factors (protein concentration, pH, flow rate and adsorption time) and responses (initial adsorption rate, adsorbed amount, desorbed extent) for hydrophilic and hydrophobic substrates, with a reduced number of experiments. This approach allows the simultaneous evaluation of the factors affecting the albumin adsorption-desorption process to find a qualitative correlation with the amount of alive S. aureus adhered on albumin biofunctionalized substrates. The results of this work point to a relationship between bacterial adhesion and the degree of albumin relaxation on the solid substrate. In fact, the inhibition of bacterial adhesion on albumin biofunctionalized substrates is due to the surface perturbation on the native structure of the protein. On this base, a biofunctionalization strategy was designed using a solution of thermally treated albumin molecules (higher ß-sheet or unordered secondary structure elements) to biofunctionalize solid substrates by dipping. With these albumin biofunctionalized substrates S. aureus adhesion was minimized.
Assuntos
Aderência Bacteriana/fisiologia , Soroalbumina Bovina/química , Albumina Sérica/química , Staphylococcus aureus/fisiologia , Adsorção , Animais , Aderência Bacteriana/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Bovinos , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Humanos , Staphylococcus aureus/efeitos dos fármacos , Propriedades de SuperfícieRESUMO
A biofilm is a very complex consortium formed by a mix of different microorganisms, which have become an important health problem, because its formation is a resistance mechanism used by bacteria against antibiotics or the immune system. In this work, we show differences between some physicochemical properties of biofilms in mono- and multi-species, formed by bacteria from clinical samples of infected chronic wounds. Of the most prevalent bacteria in wounds, two mono- and one multi-species biofilms were developed in vitro by Drip Flow Reactor: one biofilm was developed by S. aureus, other by P. aeruginosa, and a third one by the mix of both strains. With these biofilms, we determined microbial growth by plate counting, and their physicochemical characterization by Atomic Force Microscopy, Raman Micro-Spectroscopy and Scanning Electron Microscopy. We found that the viability of S. aureus was less than P. aeruginosa in multi-species biofilm. However, the adhesion force of S. aureus is much higher than that of P. aeruginosa, but it decreased while that of P. aeruginosa increased in the multi-species biofilm. In addition, we found free pyrimidines functional groups in the P. aeruginosa biofilm and its mix with S. aureus. Surprisingly, each bacterium alone formed single layer biofilms, while the mix bacteria formed a multilayer biofilm at the same observation time. Our results show the necessity to evaluate biofilms from clinically isolated strains and have a better understanding of the adhesion forces of bacteria in biofilm multispecies, which could be of prime importance in developing more effective treatments against biofilm formation.