RESUMO
Probiotics serve a very important role in human health. However, probiotics have poor stability during processing, storage, and gastrointestinal digestion. The gellan gum (GG) is less susceptible to enzymatic degradation and resistant to thermal and acidic environments. This study investigated the effect of casein (CS)-GG emulsions to encapsulate Lactiplantibacillus plantarum CICC 6002 (L. plantarum CICC 6002) on its storage stability, thermal stability, and gastrointestinal digestion. L. plantarum CICC 6002 was suspended in palm oil and emulsions were prepared using CS or CS-GG complexes. We found the CS-GG emulsions improved the viability of L. plantarum CICC 6002 after storage, pasteurization, and digestion compared to the CS emulsions. In addition, we investigated the influence of the gellan gum concentration on emulsion stability, and the optimal stability was observed in the emulsion prepared by CS-0.8% GG complex. This study provided a new strategy for the protection of probiotics based on CS-GG delivery system.
Assuntos
Caseínas , Emulsões , Lactobacillus plantarum , Polissacarídeos Bacterianos , Probióticos , Emulsões/química , Probióticos/química , Polissacarídeos Bacterianos/química , Caseínas/química , Humanos , Lactobacillus plantarum/química , Lactobacillus plantarum/metabolismo , Pasteurização , Trato Gastrointestinal/microbiologia , Trato Gastrointestinal/metabolismo , Viabilidade Microbiana/efeitos dos fármacos , Composição de Medicamentos , Digestão , Armazenamento de AlimentosRESUMO
Introduction: Our work aims at establishing a proof-of-concept for a method that allows the early prediction of the bactericidal and bacteriostatic effects of antibiotics on bacteria using scanning electron microscopy (SEM) as compared to traditional culture-based methods. Methods: We tested these effects using Imipenem (bactericidal) and Doxycycline (bacteriostatic) with several strains of sensitive and resistant Escherichia coli. We developed a SEM-based predictive score based on three main criteria: Bacterial Density, Morphology/Ultrastructure, and Viability. We determined the results for each of these criteria using SEM micrographs taken with the TM4000Plus II-Tabletop-SEM (Hitachi, Japan) following an optimized, rapid, and automated acquisition and analysis protocol. We compared our method with the traditional culture colony counting gold standard method and classic definitions of the two effects. Results: Our method revealed total agreement with the CFU method and classic definition by visualizing the effect of the antibiotic at 60 minutes and 120 minutes using SEM. Discussion: This early prediction allows a rapid and early identification of the bactericidal and bacteriostatic effects as compared to culture that would take a minimum of 18 hours. This has several future applications in the development of SEM-automated assays coupled to machine learning models that identify the antibiotic effect and facilitate determination of bacterial susceptibility.
Assuntos
Antibacterianos , Doxiciclina , Escherichia coli , Imipenem , Testes de Sensibilidade Microbiana , Viabilidade Microbiana , Microscopia Eletrônica de Varredura , Antibacterianos/farmacologia , Imipenem/farmacologia , Doxiciclina/farmacologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/ultraestrutura , Viabilidade Microbiana/efeitos dos fármacos , Contagem de Colônia MicrobianaRESUMO
Background: In the face of increasing antifungal resistance among Candida albicans biofilms, this study explores the efficacy of a combined treatment using Kangbainian lotion (KBN) and miconazole nitrate (MN) to address this challenge. Methods: Using UPLC-Q-TOF/MS Analysis for Identification of Active Compounds in KBN Lotion; FICI for synergy evaluation, XTT and ROS assays for biofilm viability and oxidative stress, fluorescence and confocal laser scanning microscopy (CLSM) for structural and viability analysis, and real-time fluorescence for gene expression. Conclusion: Our study indicates that the combined application of KBN and MN somewhat impacts the structural integrity of Candida albicans biofilms and affects the expression of several key genes involved in biofilm formation, including ALS1, ALS3, HWP1, HSP90, and CSH1. These preliminary findings suggest that there may be a synergistic effect between KBN and MN, potentially influencing not only the structural aspects of fungal biofilms but also involving the modulation of genetic pathways during their formation.
Assuntos
Antifúngicos , Biofilmes , Candida albicans , Farmacorresistência Fúngica , Sinergismo Farmacológico , Miconazol , Testes de Sensibilidade Microbiana , Biofilmes/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Antifúngicos/farmacologia , Miconazol/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Viabilidade Microbiana/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Extratos Vegetais/farmacologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , HumanosRESUMO
The primary aim of this study was to investigate the impact of treatment with low-temperature plasma (LTP) for varying exposure durations on a multispecies cariogenic biofilm comprising C. albicans, L. casei, and S. mutans, as well as on single-species biofilms of L. casei and C. albicans, cultured on hydroxyapatite discs. Biofilms were treated with LTP-argon at a 10 mm distance for 30 s, 60 s, and 120 s. Chlorhexidine solution (0.12%) and NaCl (0.89%) were used as positive (PC) and negative controls (NC), respectively. Argon flow only was also used as gas flow control (F). Colony-forming units (CFU) recovery and confocal laser scanning microscopy (CLSM) were used to analyze biofilm viability. LTP starting at 30 s of application significantly reduced the viability of multispecies biofilms by more than 2 log10 in all treated samples (p < 0.0001). For single-species biofilms, L. casei showed a significant reduction compared to PC and NC of over 1 log10 at all exposure times (p < 0.0001). In the case of C. albicans biofilms, LTP treatment compared to PC and NC resulted in a significant decrease in bacterial counts when applied for 60 and 120 s (1.55 and 1.90 log10 CFU/mL, respectively) (p < 0.0001). A significant effect (p ≤ 0.05) of LTP in single-species biofilms was observed to start at 60 s of LTP application compared to F, suggesting a time-dependent effect of LTP for the single-species biofilms of C. albicans and L. casei. LTP is a potential mechanism in treating dental caries by being an effective anti-biofilm therapy of both single and multispecies cariogenic biofilms.
Assuntos
Biofilmes , Candida albicans , Gases em Plasma , Streptococcus mutans , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Gases em Plasma/farmacologia , Candida albicans/fisiologia , Candida albicans/efeitos dos fármacos , Streptococcus mutans/efeitos dos fármacos , Streptococcus mutans/fisiologia , Cárie Dentária/microbiologia , Cárie Dentária/terapia , Lacticaseibacillus casei/fisiologia , Humanos , Viabilidade Microbiana/efeitos dos fármacos , Microscopia Confocal , Temperatura BaixaRESUMO
The preservation of microorganisms is pivotal in microbiological practice. Currently, cryopreservation is assumed to be an effective and inexpensive approach for the storage of microorganisms, including bacteria. The key point of cryopreservation is optimal cryoprotectant selection. In the present study, different cryoprotectant compositions were tested for long-term storage of 15 Enterobacterales bacterial strains at - 20 °C. The survival rates of the bacterial strains were evaluated in four different cryoprotectant solutions containing 70% glycerin only (cryoprotectants 1 and 4), 10% dimethyl sulfoxide (DMSO) with 70% glycerin (cryoprotectant 2), and 10% DMSO (cryoprotectant 3). In addition, cryoprotectants 1 and 2 contained peptone and yeast extract as nutritional supplements. The general survival rates of the bacterial strains were evaluated after 12 months of storage. After 12 months, the survival rates of the different cryoprotectants were as follows: cryoprotectant 1-88.87%; cryoprotectant 2-84.85%; cryoprotectant 3-83.50%; and cryoprotectant 4-44.81%. Thus, the composition of cryoprotectant 1 (70% glycerin with nutrient supplements) was optimal for preserving 15 tested strains of the order Enterobacterales. Despite these findings, the biochemical properties of the tested strains changed after cryopreservation for 12 months in the presence of 1 or 3 cryoprotectants. Alterations in the biochemical profile could be related to changes in environmental conditions and cold adaptation. We assume that the composition of cryoprotectant 1 can be optimal for storing the order Enterobacterales at - 20 °C. However, further investigations are needed to elucidate the problem of cryopreservation and to support our assumption.
Assuntos
Criopreservação , Crioprotetores , Enterobacteriaceae , Viabilidade Microbiana , Crioprotetores/farmacologia , Criopreservação/métodos , Viabilidade Microbiana/efeitos dos fármacos , Enterobacteriaceae/efeitos dos fármacos , Enterobacteriaceae/crescimento & desenvolvimento , Dimetil Sulfóxido/farmacologia , Glicerol/farmacologiaRESUMO
Acinetobacter species such as A. venetianus and A. guillouiae have been studied for various biotechnology applications, including bioremediation of recalcitrant and harmful environmental contaminants, as well as bioengineering of enzymes and diagnostic materials. Bacteria used in biotechnology are often combined with other microorganisms in mixtures to formulate efficacious commercial products. However, if the mixture contained a closely related Acinetobacter pathogen such as A. baumannii (Ab), it remains unclear whether the survival and virulence of Ab would be masked or augmented. This uncertainty poses a challenge in ensuring the safety of such biotechnology products, since Ab is one of the most significant pathogens for both hospital and community -acquired infections. This research aimed to investigate the growth and virulence of Ab within a mixture of 11 bacterial species formulated as a mock microbial mixture (MM). Growth challenges with environmental stressors (i.e., temperature, pH, sodium, iron, and antibiotics) revealed that Ab could thrive under diverse conditions except in the presence of ciprofloxacin. When cultured alone, Ab exhibited significantly more growth in the presence of almost all the environmental stressors than when it was co-incubated with the MM. During the exposure of A549 lung epithelial cells to the MM, Ab growth was stimulated compared to that in standard mammalian culture media. Cytotoxicity caused by Ab was suppressed in the presence of the MM. Lymphocytes were significantly reduced in mice exposed to Ab with or without MM via intravenous injection. The levels of the splenic cytokines IL-1α, IL-1ß, MCP-1, and MIP-1α were significantly reduced 24 h after exposure to Ab + MM. This study demonstrated that the presence of the MM marginally but significantly reduced the growth and virulence of Ab, which has implications for the safety of mixtures of microorganisms for biotechnological applications. Furthermore, these findings expand our understanding of the virulence of Ab during host-pathogen interactions.
Assuntos
Infecções por Acinetobacter , Acinetobacter baumannii , Animais , Acinetobacter baumannii/patogenicidade , Acinetobacter baumannii/crescimento & desenvolvimento , Acinetobacter baumannii/efeitos dos fármacos , Acinetobacter baumannii/genética , Virulência , Camundongos , Humanos , Infecções por Acinetobacter/microbiologia , Células A549 , Antibacterianos/farmacologia , Feminino , Citocinas/metabolismo , Viabilidade Microbiana/efeitos dos fármacosRESUMO
Agricultural yields are often limited by damage caused by pathogenic microorganisms, including plant-pathogenic bacteria. The chemical control options to cope with bacterial diseases in agriculture are limited, predominantly relying on copper-based products. These compounds, however, possess limited efficacy. Therefore, there is an urgent need to develop novel technologies to manage bacterial plant diseases and reduce food loss. In this study, a new antimicrobial agent was developed using a doping method that entraps small bioactive organic molecules inside copper as the metal matrix. The food preservative agent lauroyl arginate ethyl ester (ethyl lauroyl arginate; LAE) was chosen as the doped organic compound. The new composites were termed LAE@[Cu]. Bactericidal assays against Acidovorax citrulli, a severe plant pathogen, revealed that LAE and copper in the composites possess a synergistic interaction as compared with each component individually. LAE@[Cu] composites were further characterised in terms of chemical properties and in planta assays demonstrated their potential for further development as crop protection agents.
Assuntos
Cobre , Proteção de Cultivos , Doenças das Plantas , Cobre/química , Cobre/farmacologia , Proteção de Cultivos/métodos , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Comamonadaceae/efeitos dos fármacos , Comamonadaceae/química , Anti-Infecciosos/farmacologia , Anti-Infecciosos/química , Arginina/química , Arginina/farmacologia , Arginina/análogos & derivados , Antibacterianos/farmacologia , Antibacterianos/química , Viabilidade Microbiana/efeitos dos fármacosRESUMO
Bacteriophages have been proposed as biological controllers to protect plants against different bacterial pathogens. In this scenario, one of the main challenges is the low viability of phages in plants and under adverse environmental conditions. This work explores the use of 12 compounds and 14 different formulations to increase the viability of a phage mixture that demonstrated biocontrol capacity against Pseudomonas syringae pv. actinidiae (Psa) in kiwi plants. The results showed that the viability of the phage mixture decreases at 44 °C, at a pH lower than 4, and under UV radiation. However, using excipients such as skim milk, casein, and glutamic acid can prevent the viability loss of the phages under these conditions. Likewise, it was demonstrated that the use of these compounds prolongs the presence of phages in kiwi plants from 48 h to at least 96 h. In addition, it was observed that phages remained stable for seven weeks when stored in powder with skim milk, casein, or sucrose after lyophilization and at 4 °C. Finally, the phages with glutamic acid, sucrose, or skim milk maintained their antimicrobial activity against Psa on kiwi leaves and persisted within kiwi plants when added through roots. This study contributes to overcoming the challenges associated with the use of phages as biological controllers in agriculture.
Assuntos
Doenças das Plantas , Pseudomonas syringae , Pseudomonas syringae/virologia , Pseudomonas syringae/efeitos dos fármacos , Doenças das Plantas/virologia , Doenças das Plantas/prevenção & controle , Doenças das Plantas/microbiologia , Agricultura/métodos , Actinidia/química , Bacteriófagos/fisiologia , Viabilidade Microbiana/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Agentes de Controle Biológico/farmacologia , Excipientes/química , Excipientes/farmacologia , Folhas de Planta/virologia , Folhas de Planta/químicaRESUMO
Chlorine and its derivatives have been used as an antibacterial agent to reduce Salmonella contamination in poultry meat during processing. We evaluated the survival of 4 different Salmonella serotypes (Typhimurium, Enteritidis, Heidelberg, and Gaminara) in the presence of 50 ppm sodium hypochlorite (NaOCl) alone or with the addition of thiourea (radical scavenger) or Dip (iron chelator) to determine the contribution of reactive oxygen species (ROS) in the bactericidal activity of NaOCl. The result showed that for all four serotypes the addition of thiourea or Dip significantly increased the % survival as compared to the respective NaOCl treatment groups, while it was significantly higher with thiourea as compared to Dip (P < 0.05). We also evaluated the survival of 11 deletion mutants of S. Typhimurium, which were demonstrated to increase (∆atpC, ∆cyoA, ∆gnd, ∆nuoG, ∆pta, ∆sdhC, and ∆zwf) or decrease the production of ROS (∆edd, ∆fumB, ∆pykA, and ∆tktB) in Escherichia coli (E. coli), in the presence of 50 ppm. The results showed that only two (∆sdhC and ∆zwf) out of 7 ROS-increasing mutants showed reduced % survival as compared to the wild-type (P < 0.05), while all four deletion ROS-decreasing mutants showed significantly higher % survival as compared to the wild-type (P < 0.05). This work suggests that the production of ROS is a major component of the bactericidal activity of NaOCl against Salmonella serotypes and there might be a significant difference in the metabolic pathways involved in ROS production between Salmonella and E. coli.
Assuntos
Antibacterianos , Espécies Reativas de Oxigênio , Salmonella , Espécies Reativas de Oxigênio/metabolismo , Salmonella/efeitos dos fármacos , Salmonella/genética , Antibacterianos/farmacologia , Hipoclorito de Sódio/farmacologia , Cloro/farmacologia , Desinfetantes/farmacologia , Viabilidade Microbiana/efeitos dos fármacos , Tioureia/farmacologia , Tioureia/análogos & derivados , Animais , Escherichia coli/efeitos dos fármacos , Escherichia coli/genéticaRESUMO
Bacterial spores in materials and equipment pose significant biosecurity risks, making effective disinfection crucial. This study evaluated Ortho-phthalaldehyde (OPA) and a quaternary ammonia-glutaraldehyde solution (AG) for inactivating spores of Bacillus thuringiensis (BT), B. cereus (BC), and two strains of B. velezensis (BV1 and BV2). Spores of BV1 and BT were treated with 22.5 mg/m3 OPA by dry fumigation or 1 mg/mL AG by spray for 20 min, according to the manufacturer's recommendation. As no sporicidal effect was observed, OPA was tested at 112.5 mg/m3 for 40 min, showing effectiveness for BT but not for BV1. Minimum bactericidal concentration (MBC) tests revealed higher MBC values for glutaraldehyde, prompting an overnight test with 112.5 mg/m3 OPA by dry fumigation and 50 mg/mL AG by spray, using formaldehyde as a control. AG reduced all Bacillus strains, but with limited sporicidal effect. OPA was sporicidal for BT and BV1 but not for BC and BV2, indicating a strain-dependent effect. Formaldehyde performed better overall but did not completely inactivate BV2 spores. Our findings suggest that OPA and AG have potential as formaldehyde replacements in wet disinfection procedures.
Assuntos
Bacillus thuringiensis , Bacillus , Desinfetantes , Glutaral , Esporos Bacterianos , Desinfetantes/farmacologia , Esporos Bacterianos/efeitos dos fármacos , Bacillus/efeitos dos fármacos , Bacillus/fisiologia , Glutaral/farmacologia , Bacillus thuringiensis/efeitos dos fármacos , Bacillus thuringiensis/fisiologia , Testes de Sensibilidade Microbiana , o-Ftalaldeído/farmacologia , Bacillus cereus/efeitos dos fármacos , Viabilidade Microbiana/efeitos dos fármacos , Desinfecção/métodosRESUMO
To realize the health benefits of probiotic bacteria, they must withstand processing and storage conditions and remain viable after use. The encapsulation of these probiotics in the form of microspheres containing tapioca flour as a prebiotic and vehicle component in their structure or shell affords symbiotic effects that improve the survival of probiotics under unfavorable conditions. Microencapsulation is one such method that has proven to be effective in protecting probiotics from adverse conditions while maintaining their viability and functionality. The aim of the work was to obtain high-quality microspheres that can act as carriers of Lactobacillus casei bacteria and to assess the impact of encapsulation on the viability of probiotic microorganisms in alginate microspheres enriched with a prebiotic (tapioca flour) and additionally coated with hyaluronic acid, chitosan, or gelatin. The influence of the composition of microparticles on the physicochemical properties and the viability of probiotic bacteria during storage was examined. The optimal composition of microspheres was selected using the design of experiments using statistical methods. Subsequently, the size, morphology, and cross-section of the obtained microspheres, as well as the effectiveness of the microsphere coating with biopolymers, were analyzed. The chemical structure of the microspheres was identified by using Fourier-transform infrared spectrophotometry. Raman spectroscopy was used to confirm the success of coating the microspheres with the selected biopolymers. The obtained results showed that the addition of tapioca flour had a positive effect on the surface modification of the microspheres, causing the porous structure of the alginate microparticles to become smaller and more sealed. Moreover, the addition of prebiotic and biopolymer coatings of the microspheres, particularly using hyaluronic acid and chitosan, significantly improved the survival and viability of the probiotic strain during long-term storage. The highest survival rate of the probiotic strain was recorded for alginate-tapioca flour microspheres coated with hyaluronic acid, at 5.48 log CFU g-1. The survival rate of L. casei in that vehicle system was 89% after storage for 30 days of storage.
Assuntos
Alginatos , Lacticaseibacillus casei , Manihot , Microesferas , Probióticos , Lacticaseibacillus casei/química , Alginatos/química , Alginatos/farmacologia , Probióticos/química , Manihot/química , Farinha , Biopolímeros/química , Biopolímeros/farmacologia , Quitosana/química , Quitosana/farmacologia , Viabilidade Microbiana/efeitos dos fármacos , Ácido Hialurônico/química , Ácido Hialurônico/farmacologiaRESUMO
Lactobacillus acidophilus is a probiotic commonly used in aquaculture to enhance the growth and immune system of aquatic species through the synthesis of various enzymes, and antimicrobial compounds like lactic acid. Traditional method of growing L. acidophilus involes using the De Man-Rogosa-Sharpe (MRS) medium. However, L. acidophilus belongs to a non-spore forming group, which make it vulnerable to stress conditions, especially during the usage process. Therefore, the present study aimed to improve the survival rate, antibacterial activity, and enrich the polyunsaturated fatty acids (PUFAs) content of L. acidophilus LB when cultured in an algae-supplemented medium, thus increasing its benefits in aquaculture applications. Using different algae biomass species as an alternative to MRS medium for the growth of L. acidophilus LB, the results showed that Spirulina platensis promoted the highest density of L. acidophilus LB. When grown in (S. platensis + glucose) medium, L. acidophilus LB produced the highest lactic acid concentration of 18.24 ± 2.43 mg/mL and survived in extreme conditions such as 4% NaCl, pH 1.0-2.0, and 50 ºC, and inhibited 99.82 ± 0.24% of Vibrio parahaemolyticus population after 2 days of treatment. Additionally, it was observed that the PUFAs content, specifically omega-6, and -7, also increased in the fermentation mixture as compared to the control sample. These findings highlighted the potential of utilizing the cyanobacteria S. platensis as an alternative, eco-friendly growth substance for L. acidophilus LB to enhance its bioactivity and viability under extreme conditions.
Assuntos
Meios de Cultura , Lactobacillus acidophilus , Probióticos , Spirulina , Lactobacillus acidophilus/metabolismo , Lactobacillus acidophilus/crescimento & desenvolvimento , Spirulina/metabolismo , Spirulina/crescimento & desenvolvimento , Spirulina/química , Probióticos/metabolismo , Meios de Cultura/química , Meios de Cultura/metabolismo , Ácidos Graxos Ômega-6/metabolismo , Viabilidade Microbiana/efeitos dos fármacos , Antibacterianos/farmacologia , Ácidos Graxos Insaturados/metabolismo , Ácido Láctico/metabolismo , AquiculturaRESUMO
While probiotics have a wide range of beneficial properties, they can also negatively affect the taste or aroma of foods products by resulting in the phenomenon of post-acidification. Ultrasound (US) is a tool to modulate the metabolism of probiotic bacteria, counteracting post-acidification and improving the performance and functional properties of microorganisms without affecting their viability. The purpose of this paper was to evaluate the effect of 10 different combinations of power (20 and 40 %) and duration (2, 4, 6, 8 and 10 min) of US treatment on two functional strains of Lactiplantibacillus plantarum (c16 and c19) isolated from table olives, with the aim of understanding how, some of the main functional and technological traits (viability, acidification, growth profile under different conditions, antibiotic resistance, viability at pH 2.0 and 0.3 % bile salts), were affected. It was found that the effects were strain dependent, and the best results were obtained for strain c19 in the combinations at 20 % for 8 and 10 min and 40 % for 2 min, where an improvement in functional characteristics was found, with some effects on biofilm stability, inhibition of acidification, without adverse results on some technological properties.
Assuntos
Olea , Olea/microbiologia , Concentração de Íons de Hidrogênio , Biofilmes/efeitos dos fármacos , Ondas Ultrassônicas , Viabilidade Microbiana/efeitos dos fármacos , Lactobacillus plantarum/isolamento & purificação , Lactobacillus plantarum/fisiologia , Lactobacillus plantarum/metabolismo , ProbióticosRESUMO
Photodynamic inactivation is an emerging antimicrobial treatment that can be enhanced by employing exogenous photosensitizers to eradicate foodborne pathogens. This study investigated a novel combinatory strategy to eradicate Listeria monocytogenes using blackthorn fruit peel (BFP) and blue light (BL). Extracts of BFP were characterized in terms of polyphenolic content, individual constituents, and antioxidant and antimicrobial activity. The concentration of phenolic compounds and antioxidant activity were both found to be determinants of antimicrobial activity. It was further speculated that flavonols, predominantly quercetin and rutin, were responsible for the activity of BFP against L. monocytogenes. A combination of BFP and BL resulted in a rapid inactivation of the pathogen by up to 4 log CFU/mL at 58.5 J/cm2, corresponding to 15 min BL illumination. Flow cytometry analysis revealed that the bacterial cells lost activity and suffered extensive membrane damage, exceeding 90% of the population. After photosensitizing L. monocytogenes with the BFP constituents quercetin and rutin, a 1.3-log reduction was observed. When applied together, these compounds could inflict the same damaging effect on cells as they did individually when effects were added. Therefore, the results indicate that BFP represents a natural source of (pro-)photosensitizers, which act additively to create inactivation effects. This study may help identify more effective plant-based photosensitizers to control L. monocytogenes in food-related applications.
Assuntos
Frutas , Luz , Listeria monocytogenes , Fármacos Fotossensibilizantes , Extratos Vegetais , Polifenóis , Listeria monocytogenes/efeitos dos fármacos , Listeria monocytogenes/efeitos da radiação , Listeria monocytogenes/crescimento & desenvolvimento , Polifenóis/farmacologia , Extratos Vegetais/farmacologia , Extratos Vegetais/química , Frutas/química , Frutas/microbiologia , Fármacos Fotossensibilizantes/farmacologia , Crataegus/química , Antibacterianos/farmacologia , Antioxidantes/farmacologia , Quercetina/farmacologia , Viabilidade Microbiana/efeitos dos fármacos , Viabilidade Microbiana/efeitos da radiação , Luz AzulRESUMO
This study aimed to assess the impact of adaptation of ten strains of O157:H7 and non-O157 Escherichia coli to low pH (acid shock or slow acidification) and the effects of this exposure or not on the resistance of E. coli strains to UV radiation in orange juice (pH 3.5). The acid-shocked cells were obtained through culture in tryptic soy broth (TSB) with a final pH of 4.8, which was adjusted by hydrochloric, lactic, or citric acid and subsequently inoculated in orange juice at 4 °C for 30 days. No significant differences (p > 0.05) in survival in orange juice were observed between the serotypes O157:H7 and non-O157:H7 for acid-shocked experiments. After slow acidification, where the cells were cultured in TSB supplemented with glucose 1% (TSB + G), a significant increase (p < 0.05) in survival was observed for all strains evaluated. The D-values (radiation dose (J/cm2) necessary to decrease the microbial population by 90%) were determined as the inverse of the slopes of the regressions (k) obtained by plotting log (N/N0). The results show that among the strains tested, E. coli O157:H7 (303/00) and O26:H11 were the most resistant and sensitive strains, respectively. According to our results, the method of acid adaptation contributes to increasing the UV resistance for most of the strains tested.
Assuntos
Adaptação Fisiológica , Citrus sinensis , Escherichia coli O157 , Sucos de Frutas e Vegetais , Raios Ultravioleta , Escherichia coli O157/efeitos da radiação , Escherichia coli O157/crescimento & desenvolvimento , Escherichia coli O157/efeitos dos fármacos , Sucos de Frutas e Vegetais/microbiologia , Sucos de Frutas e Vegetais/análise , Citrus sinensis/microbiologia , Citrus sinensis/química , Concentração de Íons de Hidrogênio , Escherichia coli/efeitos da radiação , Escherichia coli/efeitos dos fármacos , Ácidos/farmacologia , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Viabilidade Microbiana/efeitos da radiação , Viabilidade Microbiana/efeitos dos fármacos , Irradiação de AlimentosRESUMO
This study proposes an affordable plasma device that utilizes a parallel-plate dielectric barrier discharge geometry with a metallic mesh electrode, featuring a straightforward 3D-printed design. Powered by a high-voltage supply adapted from a cosmetic plasma device, it operates on atmospheric air, eliminating the need for gas flux. Surface modification of polyethylene treated with this device was characterized and showed that the elemental composition after 15 min of plasma treatment decreased the amount of C to ~80 at% due to the insertion of O (~15 at%). Tested against Candida albicans and Staphylococcus aureus, the device achieved a reduction of over 99% in microbial load with exposure times ranging from 1 to 10 min. Simultaneously, the Vero cell viability remained consistently high, namely between 91% and 96% across exposure times. These results highlight this device's potential for the surface modification of materials and various infection-related applications, boasting affordability and facilitating effective antimicrobial interventions.
Assuntos
Candida albicans , Gases em Plasma , Staphylococcus aureus , Propriedades de Superfície , Candida albicans/efeitos dos fármacos , Gases em Plasma/química , Gases em Plasma/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Animais , Células Vero , Chlorocebus aethiops , Viabilidade Microbiana/efeitos dos fármacos , Polímeros/químicaRESUMO
The present study evaluates the in-vitro antibiofilm activity against the biofilm formed by Staphylococcus aureus, and the wound-healing efficacy of two different types of rhamnolipids produced by Pseudomonas aeruginosa strain JS29 in S.aureus infected wounds. The biosurfactant production was carried out in a mineral salt medium supplemented with 2 % Glucose and 2 % Glycerol individually and thus were designated as RL-Glu and RL-Gly respectively. 0.5 mg/ml of RL-Glu and RL-Gly demonstrated 90 % growth inhibition of S. aureus while exhibiting bactericidal activity at 4 mg/ml of RL-Glu and 1 mg/ml of RL-Gly. Both types of rhamnolipid cause changes in membrane permeability leading to pathogens' non-viability. 90 % inhibition of biofilm formation by S. aureus was observed at 2 mg/ml of RL-Glu and 0.5 mg/ml of RL-Gly, while 0.5 mg/ml of both rhamnolipid disrupted 90 % of the preformed biofilm. 0.5 mg/ml of RL-Glu and RL-Gly decreases the production of exopolysaccharides and also causes structural alteration. 0.5 mg/ml of RL-Glu and RL-Gly were found to exhibit effective wound healing efficacy in S. aureus infected wounds within 7 days of treatment. Histopathological studies of wound sites revealed efficient wound management by both the rhamnolipid. LCMS and GCMS characterization of the biosurfactant revealed that JS29 produces different rhamnolipid congeners when grown on different carbon sources, thereby influencing the antimicrobial, antibiofilm, and wound healing efficacy of rhamnolipid.
Assuntos
Antibacterianos , Biofilmes , Glicolipídeos , Pseudomonas aeruginosa , Staphylococcus aureus , Tensoativos , Cicatrização , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Glicolipídeos/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Tensoativos/farmacologia , Cicatrização/efeitos dos fármacos , Pseudomonas aeruginosa/efeitos dos fármacos , Antibacterianos/farmacologia , Infecções Estafilocócicas/tratamento farmacológico , Infecções Estafilocócicas/microbiologia , Animais , Testes de Sensibilidade Microbiana , Infecção dos Ferimentos/tratamento farmacológico , Infecção dos Ferimentos/microbiologia , Viabilidade Microbiana/efeitos dos fármacos , CamundongosRESUMO
Dental plaque, formed by a Streptococcus mutans biofilm, is a major contributor to cavity formation. While antimicrobial strategies exist, the growing risk of antibiotic resistance necessitates alternative therapeutic solutions. Polyserotonin nanoparticles (PSeNPs), recently recognized for their photothermal property and promising biomedical applications, open up a new avenue for antimicrobial use. Here, we introduced a UV-initiated synthetic route for PSeNPs with improved yield. Using these PSeNPs, a cocktail treatment to reduce the viability of this cavity-causing bacteria was developed. This cocktail comprises an S. mutans-targeting antimicrobial peptide (GH12), an intraspecies competence-stimulating peptide that triggers altruistic cell death in S. mutans, and laser-activated heating of PSeNPs. The "peptide + PSeNP + laser" combination effectively inhibits S. mutans growth in both planktonic and biofilm states. Moreover, the cocktail approach remains effective in reducing the viability of S. mutans in a more virulent dual-species biofilm with Candida albicans. Overall, our results reinforce the utility of a multipronged therapeutic strategy to reduce cariogenic bacteria in the complex model oral biofilm.
Assuntos
Biofilmes , Nanopartículas , Streptococcus mutans , Streptococcus mutans/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Nanopartículas/química , Candida albicans/efeitos dos fármacos , Antibacterianos/farmacologia , Antibacterianos/química , Peptídeos Antimicrobianos/farmacologia , Peptídeos Antimicrobianos/química , Humanos , Viabilidade Microbiana/efeitos dos fármacos , Testes de Sensibilidade MicrobianaRESUMO
Biofilm formation enhances bacterial survival and antibiotic tolerance, but the underlying mechanisms are incompletely understood. Here, we show that biofilm growth is accompanied by a reduction in bacterial energy metabolism and membrane potential, together with metabolic exchanges between the inner and outer regions in biofilms. More specifically, nutrient-starved cells in the interior supply amino acids to cells in the periphery, while peripheral cells experience a decrease in membrane potential and provide fatty acids to interior cells. Fatty acids facilitate the repair of starvation-induced membrane damage in inner cells and enhance their survival in the presence of antibiotics. Thus, metabolic exchanges between inner and outer cells contribute to survival of the nutrient-starved inner cells and contribute to antibiotic tolerance within the biofilm.
Assuntos
Antibacterianos , Biofilmes , Ácidos Graxos , Biofilmes/crescimento & desenvolvimento , Biofilmes/efeitos dos fármacos , Ácidos Graxos/metabolismo , Antibacterianos/farmacologia , Viabilidade Microbiana/efeitos dos fármacos , Metabolismo Energético , Potenciais da Membrana , Aminoácidos/metabolismoRESUMO
Respiratory diseases in ruminants are responsible for enormous economic losses for the dairy and meat industry. The main causative bacterial agent of pneumonia in ovine is Mannheimia haemolytica A2. Due to the impact of this disease, the effect of the antimicrobial protein, bovine lactoferrin (bLf), against virulence factors of this bacterium has been studied. However, its effect on biofilm formation has not been reported. In this work, we evaluated the effect on different stages of the biofilm. Our results reveal a decrease in biofilm formation when bacteria were pre-incubated with bLf. However, when bLf was added at the start of biofilm formation and on mature biofilm, an increase was observed, which was visualized by greater bacterial aggregation and secretion of biofilm matrix components. Additionally, through SDS-PAGE, a remarkable band of ~80 kDa was observed when bLf was added to biofilms. Therefore, the presence of bLf on the biofilm was determined through the Western blot and Microscopy techniques. Finally, by using Live/Dead staining, we observed that most of the bacteria in a biofilm with bLf were not viable. In addition, bLf affects the formation of a new biofilm cycle. In conclusion, bLf binds to the biofilm of M. haemolytica A2 and affects the viability of bacteria and the formation a new biofilm cycle.