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1.
J Photochem Photobiol B ; 203: 111730, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31855718

RESUMO

OBJECTIVE: To explore the effectiveness, biosafety, photobleaching and mechanism of antimicrobial photodynamic therapy (aPDT) using methylene blue (MB) plus potassium iodide (KI), for root canal infections. METHODS: Different combinations and concentrations of MB, KI and 660 nm LED light were used against E. faecalis in planktonic and in biofilm states by colony-forming unit (CFU), confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM). Human gingival fibroblasts (HGF) were used for safety testing by Cell Counting Kit-8 (CCK8) and fluorescence microscopy (FLM). The photobleaching effect and mechanisms were analyzed. RESULTS: KI could not only enhance MB aPDT on E. faecalis in both planktonic and biofilm states even in a hypoxic environment, but also produced a long-lasting bactericidal effect after end of the illumination. KI could accelerate photobleaching to reduce tooth staining by MB, and the mixture was harmless for HGFs. Mechanistic studies showed the generation of hydrogen peroxide and free iodine, and iodine radicals may be formed in hypoxia. CONCLUSION: aPDT with MB plus KI could be used for root canal disinfection and clinical studies are worth pursuing.


Assuntos
Biofilmes/efeitos dos fármacos , Cavidade Pulpar/microbiologia , Enterococcus faecalis/fisiologia , Azul de Metileno/farmacologia , Plâncton/efeitos dos fármacos , Iodeto de Potássio/farmacologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Enterococcus faecalis/efeitos dos fármacos , Humanos , Peróxido de Hidrogênio/metabolismo , Iodo/metabolismo , Luz , Microscopia Confocal , Microscopia Eletrônica de Varredura , Fotodegradação/efeitos dos fármacos
2.
Food Microbiol ; 86: 103337, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31703870

RESUMO

Coenzyme Q0 (CoQ0) has demonstrated antitumor, anti-inflammatory, and anti-angiogenic activities. Cronobacter sakazakii is an opportunistic foodborne pathogen associated with high mortality in neonates. In this study, the antimicrobial activity and possible antimicrobial mechanism of CoQ0 against C. sakazakii were investigated. Moreover, the inactivation effect of CoQ0 on C. sakazakii in biofilms was also evaluated. The minimum inhibitory concentration (MIC) of CoQ0 against C. sakazakii strains ranged from 0.1 to 0.2 mg/mL. Treatment caused cell membrane dysfunction, as evidenced by cell membrane hyperpolarization, decreased intracellular ATP concentration and cell membrane integrity, and changes in cellular morphology. CoQ0 combined with mild heat treatment (45, 50, or 55 °C) decreased the number of viable non-desiccated and desiccated C. sakazakii cells in a time- and dose-dependent manner in reconstituted infant milk. Furthermore, CoQ0 showed effective inactivation activity against C. sakazakii in biofilms on stainless steel, reducing the number of viable cells and damaging the structure of the biofilm. These findings suggest that CoQ0 has a strong inactivate effect on C. sakazakii and could be used in food production environments to effectively control C. sakazakii and reduce the number of illnesses associated with it.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Cronobacter sakazakii/efeitos dos fármacos , Ubiquinona/análogos & derivados , Membrana Celular/efeitos dos fármacos , Cronobacter sakazakii/crescimento & desenvolvimento , Cronobacter sakazakii/fisiologia , Fórmulas Infantis/análise , Fórmulas Infantis/microbiologia , Testes de Sensibilidade Microbiana , Plâncton/efeitos dos fármacos , Plâncton/crescimento & desenvolvimento , Plâncton/fisiologia , Ubiquinona/farmacologia
3.
Mar Pollut Bull ; 145: 316-324, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31590793

RESUMO

In 2020, the global cap of maximum allowable sulphur content in marine fuel will be reduced from the current 3.5% to 0.5%. Another way to reduce the sulphur emissions is to install a seawater scrubber that cleans exhausts but instead release acidic water containing nutrients and contaminants back to the marine environment. In the current study, scrubber washwater was tested on a Baltic Sea microplankton community. A significant increase in chlorophyll a, particulate organic phosphorus (POP), carbon (POC) and nitrogen (PON) were observed when the community was exposed to 10% scrubber washwater for 13 days as compared to the control. A laboratory experiment with the filamentous cyanobacteria Nodularia spumigena and the chain-forming diatom Melosira cf. arctica showed negative responses in photosynthetic activity (EC10 = 8.6% for N. spumigena) and increased primary productivity (EC10 = 5.5% for M. cf. arctica), implying species-specific responses to scrubber washwater discharge.


Assuntos
Plâncton/efeitos dos fármacos , Água do Mar/microbiologia , Emissões de Veículos/prevenção & controle , Poluição da Água/prevenção & controle , Países Bálticos , Clorofila A/análise , Cianobactérias/efeitos dos fármacos , Nitrogênio/análise , Nodularia/efeitos dos fármacos , Fósforo/análise , Fotossíntese/efeitos dos fármacos , Navios , Enxofre/toxicidade , Emissões de Veículos/toxicidade
4.
Int J Nanomedicine ; 14: 8133-8147, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31632023

RESUMO

Background: It is important to explore the interaction between antibacterial nanoparticles and microbes for understanding bactericidal activity and developing novel applications. It is possible that the nanoparticulate size can govern the antibacterial potency. Purpose: The purpose of this study was to evaluate the antimicrobial and antibiofilm properties of cetylpyridinium chloride (CPC)-decorated nanoemulsions against methicillin-resistant Staphylococcus aureus (MRSA). Methods: The droplet size could be adjusted by varying the percentage of squalene, the main ingredient of the oily core. Results: We fabricated cationic nanoemulsions of three different sizes, 55, 165, and 245 nm. The nanoemulsions showed greater storage stability than the self-assembled CPC micelles. The tested nanoemulsions exhibited more antimicrobial activity against Gram-positive bacteria than Gram-negative bacteria and fungi. The killing of MRSA was mainly induced by direct cell-membrane damage. This rupture led to the leakage of cytoplasmic DNA and proteins. The nanoemulsions might also degrade the DNA helix and disturb protein synthesis. The proteomic analysis indicated the significant downregulation of DNA-directed RNA polymerase (RNAP) subunits ß and ß'. The antibacterial effect of nanoemulsions increased with decreasing droplet size in the biofilm MRSA but not planktonic MRSA. The small-sized nanoemulsions had potent antibiofilm activity that showed a colony-forming unit (CFU) reduction of 10-fold compared with the control. The loss of total DNA concentration also negatively correlated with the nanoemulsion size. Conclusion: The present report established a foundation for the development of squalene@CPC nanosystems against drug-resistant S. aureus.


Assuntos
Anti-Infecciosos/farmacologia , Biofilmes/efeitos dos fármacos , Cetilpiridínio/farmacologia , Staphylococcus aureus Resistente à Meticilina/fisiologia , Nanopartículas/química , Plâncton/efeitos dos fármacos , Esqualeno/farmacologia , Antibacterianos/farmacologia , Cátions , Emulsões , Humanos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/genética , Micelas , Testes de Sensibilidade Microbiana , Nanopartículas/ultraestrutura , Proteômica
5.
Int J Nanomedicine ; 14: 5957-5976, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31440052

RESUMO

Background: Efficient localized cervicovaginal antibacterial therapy, enabling the delivery of antibiotic to the site of action at lower doses while escaping systemic drug effects and reducing the risk of developing microbial resistance, is attracting considerable attention. Liposomes have been shown to allow sustained drug release into vaginal mucosa and improve delivery of antibiotics to bacterial cells and biofilms. Azithromycin (AZI), a potent broad-spectrum macrolide antibiotic, has not yet been investigated for localized therapy of cervicovaginal infections, although it is administered orally for the treatment of sexually transmitted diseases. Encapsulation of AZI in liposomes could improve its solubility, antibacterial activity, and allow the prolonged drug release in the cervicovaginal tissue, while avoiding systemic side effects. Purpose: The objective of this study was to develop AZI-liposomes and explore their potentials for treating cervicovaginal infections. Methods: AZI-liposomes that differed in bilayer elasticity/rigidity and surface charge were prepared and evaluated under simulated cervicovaginal conditions to yield optimized liposomes, which were assessed for antibacterial activity against several planktonic and biofilm-forming Escherichia coli strains and intracellular Chlamydia trachomatis, ex vivo AZI vaginal deposition/penetration, and in vitro cytotoxicity toward cervical cells. Results: Negatively charged liposomes with rigid bilayers (CL-3), propylene glycol liposomes (PGL-2) and deformable propylene glycol liposomes (DPGL-2) were efficient against planktonic E. coli ATCC 700928 and K-12. CL-3 was superior for preventing the formation of E. coli ATCC 700928 and K-12 biofilms, with IC50 values (concentrations that inhibit biofilm viability by 50%) up to 8-fold lower than those of the control (free AZI). DPGL-2 was the most promising for eradication of already formed E. coli biofilms and for treating C. trachomatis infections. All AZI-liposomes were biocompatible with cervical cells and improved localization of the drug inside vaginal tissue compared with the control. Conclusion: The performed studies confirm the potentials of AZI-liposomes for localized cervicovaginal therapy.


Assuntos
Azitromicina/uso terapêutico , Infecções Bacterianas/tratamento farmacológico , Colo do Útero/microbiologia , Vagina/microbiologia , Animais , Antibacterianos/farmacologia , Azitromicina/farmacologia , Infecções Bacterianas/microbiologia , Infecções Bacterianas/patologia , Materiais Biocompatíveis/farmacologia , Biofilmes/efeitos dos fármacos , Chlamydia trachomatis/efeitos dos fármacos , Liberação Controlada de Fármacos , Escherichia coli/efeitos dos fármacos , Feminino , Células HeLa , Humanos , Lipossomos , Testes de Sensibilidade Microbiana , Tamanho da Partícula , Plâncton/efeitos dos fármacos , Suínos
6.
Environ Sci Pollut Res Int ; 26(26): 27112-27127, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31317435

RESUMO

In this study, we screened for the antifouling activity of 15 species plant extracts from Brazilian the Brazilian Caatinga Fabaceae against the initial colonization of natural marine bacterial biofilm. We also investigated the potential toxicity of extracts against planktonic and benthic non-target organisms. Aqueous extracts of plants collected in the Caatinga biome (PE, Brazil) were prepared and tested at different concentration levels (0, 0.5, 1, 2, 4, and 8 mg mL-1). Natural marine bacterial consortium was inoculated in multi-well plates and incubated with the different treatments for 48 h. The biofilm and planktonic bacterial density and biomass inhibition were evaluated along with biofilm biomass eradication. The extracts that showed the highest bacterial biofilm inhibition were evaluated for toxicity against microalgae and crustaceans. The biofilm and planktonic bacterial inhibition potential were evaluated through flow cytometry and spectrophotometry. The selected treatments were evaluated for their toxicity using the microalgae Chaetoceros calcitrans, the copepod Nitokra sp., and the brine shrimp Artemia salina as bioindicators. Our work demonstrates the biotechnological potential of Fabaceae plant compounds as a safe antifouling alternative. Anadenanthera colubrina var. cebil fruits and Apuleia leiocarpa leaf extracts showed antibiofilm activity (≥ 80%), while Myroxylon peruiferum and Dioclea grandiflora leaf extracts showed antibiotic activity. These extracts were safe to planktonic and benthic non-target organisms. The results of this study point to potential substitutes to highly toxic antifouling paints and shed light on the prospect of a yet to be explored biome for more sustainable alternatives in biofouling research.


Assuntos
Incrustação Biológica/prevenção & controle , Desinfetantes/farmacologia , Fabaceae/química , Extratos Vegetais/farmacologia , Animais , Antibacterianos/farmacologia , Antibacterianos/toxicidade , Artemia/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Brasil , Copépodes/efeitos dos fármacos , Diatomáceas/efeitos dos fármacos , Desinfetantes/toxicidade , Ecotoxicologia/métodos , Microalgas/efeitos dos fármacos , Pintura , Plâncton/efeitos dos fármacos , Plâncton/microbiologia , Extratos Vegetais/toxicidade
7.
Molecules ; 24(14)2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-31340472

RESUMO

In this study, the photothermal-induced bactericidal activity of phospholipid-decorated gold nanorods (DSPE-AuNR) suspension against Pseudomonas aeruginosa planktonic and biofilm cultures was investigated. We found that the treatment of planktonic culture of Pseudomonas aeruginosa with DSPE-AuNR suspension (0.25-0.03 nM) followed by a continuous laser beam exposure resulted in ~6 log cycle reduction of the bacterial viable count in comparison to the control. The percentage reduction of Pseudomonas aeruginosa biofilm viable count was ~2.5-6.0 log cycle upon laser excitation with different concentrations of DSPE-AuNR as compared to the control. The photothermal ablation activity of DSPE-AuNR (0.125 nM) loaded into poloxamer 407 hydrogel against Pseudomonas aeruginosa biofilm resulted in ~4.5-5 log cycle reduction in the biofilm viable count compared to the control. Moreover, transmission electron microscope (TEM) images of the photothermally-treated bacteria revealed a significant change in the bacterial shape and lysis of the bacterial cell membrane in comparison to the untreated bacteria. Furthermore, the results revealed that continuous and pulse laser beam modes effected a comparable photothermal-induced bactericidal activity. Therefore, it can be concluded that phospholipid-coated gold nanorods present a promising nanoplatform to eradicate Pseudomonas aeruginosa biofilm responsible for common skin diseases.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Ouro/farmacologia , Nanotubos/química , Plâncton/efeitos dos fármacos , Pseudomonas aeruginosa/efeitos dos fármacos , Antibacterianos/química , Biofilmes/crescimento & desenvolvimento , Biofilmes/efeitos da radiação , Contagem de Colônia Microbiana , Ouro/química , Hidrogéis/química , Terapia com Luz de Baixa Intensidade/métodos , Microscopia Eletrônica de Transmissão , Nanotubos/ultraestrutura , Fosfatidiletanolaminas/química , Plâncton/crescimento & desenvolvimento , Plâncton/efeitos da radiação , Poloxâmero/química , Pseudomonas aeruginosa/crescimento & desenvolvimento , Pseudomonas aeruginosa/efeitos da radiação , Pseudomonas aeruginosa/ultraestrutura
8.
Photodiagnosis Photodyn Ther ; 27: 218-226, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31163280

RESUMO

This study reports successful photodynamic inactivation of planktonic and biofilm cells of Enterococcus faecalis using Methylene Blue (MB) in combination with gold nanoparticles synthesized using the cell-free filtrate obtained from 3-day biomass of Trichoderma asperellum strain. Monodispersed colloidal gold nanoparticles were characterized by UV-vis absorption, TEM and DLS to be 13 ±â€¯3 nm spheres. Diode lasers with the peak-power wavelength ʎ = 660 nm (output power of 21, 41 and 68 mW; power density of 55, 108 and 179 mW∙cm-2, respectively, were used as a light source to study the effects of MB alone, the gold nanoparticles alone (AuNPs) and the MB + AuNPs mixture on the viability of E. faecalis cells. The lethal effect of planktonic cells was achieved for MB after 30 min of laser irradiation with energy fluence of 322 J∙cm-2. When MB + AuNPs mixture was used as photosensitizer, the lethal effect was achieved with energy fluence of 292 J∙cm-2. The biofilm culture was more resistant to photo-inactivation and the best bactericidal effect of MB as photosensitizer was found after light dose of 483 J∙cm-2. The bacterial cell viability was reduced by 99.92%. It was proved that MB + AuNPs mixture synergistically enhances the kill of the studied microorganism as the same light dose resulted in 99.991% kill.


Assuntos
Enterococcus faecalis/efeitos dos fármacos , Nanopartículas Metálicas/química , Azul de Metileno/farmacologia , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/farmacologia , Biofilmes/efeitos dos fármacos , Ouro , Humanos , Lasers Semicondutores , Viabilidade Microbiana/efeitos dos fármacos , Plâncton/efeitos dos fármacos
9.
PLoS One ; 14(6): e0217869, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31188854

RESUMO

Vibrio cholerae is an important human pathogen causing intestinal disease with a high incidence in developing countries. V. cholerae can switch between planktonic and biofilm lifestyles. Biofilm formation is determinant for transmission, virulence and antibiotic resistance. Due to the enhanced antibiotic resistance observed by bacterial pathogens, antimicrobial nanomaterials have been used to combat infections by stopping bacterial growth and preventing biofilm formation. In this study, the effect of the nanocomposites zeolite-embedded silver (Ag), copper (Cu), or zinc (Zn) nanoparticles (NPs) was evaluated in V. cholerae planktonic cells, and in two biofilm states: pellicle biofilm (PB), formed between air-liquid interphase, and surface-attached biofilm (SB), formed at solid-liquid interfaces. Each nanocomposite type had a distinctive antimicrobial effect altering each V. cholerae lifestyles differently. The ZEO-AgNPs nanocomposite inhibited PB formation at 4 µg/ml, and prevented SB formation and eliminated planktonic cells at 8 µg/ml. In contrast, the nanocomposites ZEO-CuNPs and ZEO-ZnNPs affect V. cholerae viability but did not completely avoid bacterial growth. At transcriptional level, depending on the nanoparticles and biofilm type, nanocomposites modified the relative expression of the vpsL, rbmA and bap1, genes involved in biofilm formation. Furthermore, the relative abundance of the outer membrane proteins OmpT, OmpU, OmpA and OmpW also differs among treatments in PB and SB. This work provides a basis for further study of the nanomaterials effect at structural, genetic and proteomic levels to understand the response mechanisms of V. cholerae against metallic nanoparticles.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Nanopartículas Metálicas/química , Nanocompostos/química , Plâncton/efeitos dos fármacos , Vibrio cholerae/efeitos dos fármacos , Antibacterianos/química , Proteínas da Membrana Bacteriana Externa/genética , Proteínas da Membrana Bacteriana Externa/metabolismo , Biofilmes/crescimento & desenvolvimento , Cobre/química , Película Dentária/efeitos dos fármacos , Película Dentária/microbiologia , Humanos , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana , Nanocompostos/ultraestrutura , Plâncton/crescimento & desenvolvimento , Prata/química , Transcrição Genética , Vibrio cholerae/crescimento & desenvolvimento , Vibrio cholerae/ultraestrutura , Zeolitas/química , Zinco/química
10.
Int J Nanomedicine ; 14: 3861-3874, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31213806

RESUMO

Purpose: Infections associated with medical devices that are caused by biofilms remain a considerable challenge for health care systems owing to their multidrug resistance patterns. Biofilms of Pseudomonas aeruginosa and Staphylococcus aureus can result in life-threatening situations which are tough to eliminate by traditional methods. Antimicrobial photodynamic inactivation (aPDT) constitutes an alternative method of killing deadly pathogens and their biofilms using reactive oxygen species (ROS). This study investigated the efficacy of enhanced in vitro aPDT of P. aeruginosa and S. aureus using malachite green conjugated to carboxyl-functionalized multi-walled carbon nanotubes (MGCNT). Both the planktonic cells and biofilms of test bacteria were demonstrated to be susceptible to the MGCNT conjugate. These MGCNT conjugates may thus be employed as a facile strategy for designing antibacterial and anti-biofilm coatings to prevent the infections associated with medical devices. Methods: Conjugation of the cationic dye malachite green to carbon nanotube was studied by UV-visible spectroscopy, high-resolution transmission electron microscopy, and Fourier transform infrared spectrometry. P. aeruginosa and S. aureus photodestruction were studied using MGCNT conjugate irradiated for 3 mins with a red laser of wavelength 660 nm and radiant exposure of 58.49 J cm-2. Results: Upon MGCNT treatment, S. aureus and P. aeruginosa were reduced by 5.16 and 5.55 log10 , respectively. Compared to free dye, treatment with MGCNT afforded improved phototoxicity against test bacteria, concomitant with greater ROS production. The results revealed improved biofilm inhibition, exopolysaccharide inhibition, and reduced cell viability in test bacteria treated with MGCNT conjugate. P. aeruginosa and S. aureus biofilms were considerably reduced to 60.20±2.48% and 67.59±3.53%, respectively. Enhanced relative MGCNT phototoxicity in test bacteria was confirmed using confocal laser scanning microscopy. Conclusion: The findings indicated that MGCNT conjugate could be useful to eliminate the biofilms formed on medical devices by S. aureus and P. aeruginosa.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Nanotubos de Carbono/química , Fotoquimioterapia , Plâncton/citologia , Plâncton/efeitos dos fármacos , Pseudomonas aeruginosa/fisiologia , Corantes de Rosanilina/farmacologia , Staphylococcus aureus/fisiologia , Cinética , Peroxidação de Lipídeos/efeitos dos fármacos , Viabilidade Microbiana/efeitos dos fármacos , Nanotubos de Carbono/ultraestrutura , Pseudomonas aeruginosa/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo , Staphylococcus aureus/efeitos dos fármacos
11.
J Appl Microbiol ; 127(2): 445-458, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31074075

RESUMO

AIMS: To synthesize silver nanoparticles (AgNPs) with cell free extract of Acinetobacter sp. and evaluate antifungal activity against planktonic and biofilm of Candida. Also, to study mechanism of antifungal action of AgNPs. METHODS AND RESULT: Acinetobacter spp were screened for synthesis of AgNPs. Physio-chemical parameters were optimized to obtained monodispersed nanoparticles. Optimized nanoparticles were characterized using spectroscopic, microscopic and diffraction techniques. Antifungal and biofilm disruption activity of AgNPs (10 ± 5 nm) were investigated against C. albicans. Mechanism of antifungal activity of nanosilver was deduced by growth curve, reactive oxygen species generation, thiol interaction and microscopic analysis. Acinetobacter sp. GWRFH 45 gave maximum synthesis of AgNPs. At optimized condition monodispersed, spherical nanoparticles were obtained which were crystalline with negative surface charge. AgNPs exhibited antifungal activity against planktonic cells and biofilm of Candida. AgNPs showed synergistic effect with amphotericin B as well as fluconazole against biofilm disruption. AgNPs were found to affect growth of Candida, generate reactive oxygen species and disrupt cellular morphology. CONCLUSIONS: Cell free extract of A. calcoaceticus GWRFH 45 has ability to synthesize AgNPs. AgNPs alone and in combination with drugs have potential to inhibit C. albicans. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report of bacteriogenic AgNPs used in combination with antifungal drugs against Candida.


Assuntos
Acinetobacter/metabolismo , Antifúngicos/farmacologia , Candida albicans/efeitos dos fármacos , Nanopartículas Metálicas , Prata/farmacologia , Anfotericina B/farmacologia , Biofilmes/efeitos dos fármacos , Candida albicans/metabolismo , Candida albicans/ultraestrutura , Sinergismo Farmacológico , Fluconazol/farmacologia , Nanopartículas Metálicas/ultraestrutura , Plâncton/efeitos dos fármacos , Plâncton/metabolismo , Espécies Reativas de Oxigênio/metabolismo
12.
Sci Total Environ ; 682: 324-332, 2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31125745

RESUMO

Anthropogenic activities can cause serious negative effects on ecosystems. Despite the ecological significance of bacterial communities, the integrated biogeography of planktonic and sedimentary bacterial communities in response to anthropogenic activities is not adequately understood. Here, we examined environmental parameters and the composition of planktonic and sedimentary bacteria in the Yulin River, a tributary of Three Gorges Reservoir, in response to changes in land use and dam construction. The results revealed that human-induced land use changes enhanced the nutrient concentrations in surface water and dam construction reduced the content of carbon and nitrogen in immediately downstream sediments. Intensified human-dominated land use showed a slight impact on sedimentary bacterial communities but largely reduced the diversity of planktonic bacterial communities. Moreover, human-induced land use changes increased the abundance of genes associated with denitrification, nitrification, and anammox in planktonic bacterial communities by 19.04%, 32.40% and 30.45%, respectively. In dam construction regions, the diversity and nutrient-related metabolic activity of sedimentary bacterial communities immediately downstream of the dam were decreased, whereas these changes were not observed in planktonic bacterial communities. Additionally, bacterial community composition was significantly related to nutrient concentrations variability and followed a distance-decay pattern. Furthermore, environmental effects explained more of the variation in planktonic bacterial community composition as compared with spatial effects did, whereas, sedimentary bacterial communities were more closely related to spatial effects. Our results demonstrated the distinct responses of planktonic and sedimentary bacterial communities to anthropogenic activities, and offered new insight for understanding their potential ecological influence on rivers.


Assuntos
Fenômenos Fisiológicos Bacterianos/efeitos dos fármacos , Monitoramento Ambiental , Sedimentos Geológicos/microbiologia , Plâncton/efeitos dos fármacos , Rios/microbiologia , Poluição Química da Água/efeitos adversos , China , Lagos/microbiologia , Plâncton/fisiologia , Microbiologia da Água
13.
Vet Res ; 50(1): 24, 2019 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-30971289

RESUMO

The impact of cortisol on Flavobacterium columnare biofilm formation was explored. Firstly, the dynamics of biofilm formation by one highly (HV) and one low virulent (LV) F. columnare isolate with and without the stress hormone cortisol under microfluidic flow conditions was characterized. This to confirm that F. columnare cells could form biofilm under cortisol supplementation, and to compare the temporal and structural differences between different treatment groups. One trial revealed that in both isolates cell aggregates resembling biofilms occurred within 7-h post-inoculation. Consequently, cell clusters were sloughed away, followed by a rebuilding of bacterial cell aggregates, suggestive for a high spreading capacity. While the HV isolate revealed cell aggregates formed upstream at all time-points, for the LV isolate this was only seen upon cortisol supplementation. Secondly, the transcriptional effect of genes (gldK, gldL, gldM, gldN, sprA, sprE, sprT, and porV) belonging to the Type IX secretion system involved in gliding motility was investigated in planktonic and biofilm cells of a HV and LV isolate to which no, a low (LD) or high (HD) dose of cortisol was added. Significantly lower expression of gliding genes gldK, gldL, gldM and gldN, and of protein secretion regulator porV was seen in the LV isolate planktonic cells supplemented with a HD-cortisol. The LV isolate biofilm cells treated with the HD-cortisol showed a significant upregulation of sprT, encoding mobile surface adhesion important in bacterial colonization. This is the first evidence for the co-regulatory effect of cortisol on biofilm formation and F. columnare gliding gene expression.


Assuntos
Aderência Bacteriana/genética , Biofilmes/crescimento & desenvolvimento , Flavobacterium/fisiologia , Expressão Gênica , Genes Bacterianos/fisiologia , Hidrocortisona/metabolismo , Animais , Biofilmes/efeitos dos fármacos , Carpas/microbiologia , Relação Dose-Resposta a Droga , Flavobacterium/efeitos dos fármacos , Flavobacterium/genética , Flavobacterium/patogenicidade , Hidrocortisona/administração & dosagem , Dispositivos Lab-On-A-Chip/veterinária , Plâncton/efeitos dos fármacos , Plâncton/crescimento & desenvolvimento , Virulência
14.
Lett Appl Microbiol ; 69(3): 168-174, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30929272

RESUMO

Antimicrobial resistance presents major global concerns to patient health. In this study, metal ions of molybdenum, rhenium, yttrium and thallium were tested against bacteria in planktonic and biofilm form using one strain of Klebsiella pneumoniae and Acinetobacter baumannii. The antimicrobial efficacy of the metal ions was evaluated against the planktonic bacterial strains using minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations, whilst the efficacy of the metal ions against biofilms was tested using a crystal violet biofilm assay. Live Dead staining was used to visualize the antimicrobial activity elicited by the metal ions on the bacterial cell. The results showed that higher concentrations of the metals were required to inhibit the growth of biofilms (72·9 mg l-1 to 416·7 mg l-1 ), in comparison to their planktonic counterparts. MICs of the metal ions (<46·9 mg l-1 ) (planktonic cells) did not affect biofilm formation. Overall, rhenium and yttrium were effective antimicrobial agents. Molybdenum demonstrated the greatest level of biotoxicity. When taking into account these results and the known toxicity of thallium, it is possible that rhenium or yttrium ions could be developed as effective biocidal formulations in order to prevent transmission in healthcare environments. SIGNIFICANCE AND IMPACT OF THE STUDY: The metal ions, molybdenum, rhenium, thallium and yttrium were tested against both Klebsiella pneumoniae and Acinetobacter baumannii in planktonic and biofilm forms. This research demonstrated that all the metal ions may be effective antimicrobial agents. However, molybdenum induced high levels of cytotoxicity, whilst, there was no significant difference in the toxicity of the other metal ions tested. When considering the results for the antimicrobial efficacy and biotoxicity of the metal ions, in conjunction with the known toxicity of thallium in certain chemical compositions, it was concluded that overall rhenium or yttrium ions may be effective antimicrobial agents, one potential application may be utilizing these metal ions in hospital surface cleaning formulations.


Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Klebsiella pneumoniae/efeitos dos fármacos , Molibdênio/farmacologia , Rênio/farmacologia , Tálio/farmacologia , Ítrio/farmacologia , Biofilmes/efeitos dos fármacos , Farmacorresistência Bacteriana/fisiologia , Humanos , Testes de Sensibilidade Microbiana , Plâncton/efeitos dos fármacos
15.
N Biotechnol ; 52: 35-41, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31026607

RESUMO

The accumulation of high amounts of petroleum-derived plastics in the environment has raised ecological and health concerns. The aim of this work was to study the biodegradative abilities of five bacterial strains, namely Pseudomonas chlororaphis, Pseudomonas citronellolis, Bacillus subtilis, Bacillus flexus and Chelatococcus daeguensis, towards polyethylene, polypropylene, polystyrene and polyvinyl chloride films under aerobic conditions. Preliminary screening resulted in the selection of P. citronellolis and B. flexus as potential PVC film degraders. Both strains were able to form a biofilm on the plastic film surface and to cause some modifications to the FTIR spectra of biomass-free PVC films. The two strains were then used to set up a PVC film biodegradation assay in 2-liter flasks. After 45 days incubation, fragmentation of the film was observed, suggesting that PVC biodegradative activity took place. Gel permeation chromatography analysis showed a reduction in average molecular weight of 10% for PVC incubated with P. citronellolis, with PVC polymer chains apparently attacked. Based on these results, the P. citronellolis strain was selected for biodegradation assays of two waste PVC films, used either nonsterile or subjected to ethanol sterilization. Chemical analyses on the incubated films confirmed the biodegradation of waste PVC plastics as shown by a gravimetric weight loss of up to about 19% after 30 days incubation. In summary, this work reports the biodegradation of PVC films by P. citronellolis and B. flexus. Both strains were shown to act mainly against PVC additives, exhibiting a low biodegradation rate of PVC polymer.


Assuntos
Bacillus/metabolismo , Cloreto de Polivinila/metabolismo , Pseudomonas/metabolismo , Bacillus/efeitos dos fármacos , Aderência Bacteriana/efeitos dos fármacos , Biodegradação Ambiental/efeitos dos fármacos , Plâncton/citologia , Plâncton/efeitos dos fármacos , Plásticos/farmacologia , Polietileno/metabolismo , Polipropilenos/metabolismo , Poliestirenos/metabolismo , Pseudomonas/efeitos dos fármacos , Termogravimetria
16.
Sci Total Environ ; 668: 1289-1297, 2019 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-31018468

RESUMO

Freshwater ecosystems face widespread diffuse and point-source contamination. Species Sensitivity Distributions (SSDs) have been used as a tool to determine chemical concentration benchmarks that represent protective levels for most species in the environment. Here we used a SSD approach to assess on the adequacy of standard planktonic organisms to reflect the response of benthic communities, critically supporting the structure and function of lotic ecosystems. For the purpose, SSDs reflecting non-lethal responses of standard planktonic and selected benthic organisms were built based on EC50 values (collected in the literature or estimated following testing herein) regarding three model contaminants: potassium dichromate (PD), 3,5-dichlorophenol (DCP) and lead chloride (LC). The derived HC5 estimates were discriminatory between chemicals and the uncertainty associated with the estimate was remarkably low. The HC5 estimates with corresponding uncertainty were generally within the same order of magnitude for the three chemicals tested, with better discrimination between chemicals regarding their hazardous potential being achieved for benthic organisms: DCP was clearly less hazardous than PD, but LC tends to be as hazardous as PD and DCP (assuming the confidence interval ranges). Moreover, benthic communities were more sensitive to both DCP and PD, in this later case the HC5 being lower by more than one order of magnitude than that found for planktonic communities; for LC, confidence intervals overlapped, preventing a feasible assumption regarding differential sensitivity of the compared communities. Microphytobenthos was highlighted as the most sensitive group to the three tested chemicals in SSDs covering the benthic compartment, while SSDs with planktonic organisms did not consistently show trends in sensitivity ordering. Overall, our results suggest that protective benchmarks retrieved from SSDs built with the responses of standard planktonic organisms (which are the most commonly used for regulation purposes) do not adequately protect benthic communities.


Assuntos
Benchmarking/métodos , Água Doce/química , Oligoquetos/efeitos dos fármacos , Plâncton/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Conservação dos Recursos Naturais/métodos , Ecossistema , Ecotoxicologia , Medição de Risco , Especificidade da Espécie , Poluentes Químicos da Água/análise
17.
J Med Microbiol ; 68(3): 493-502, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30882300

RESUMO

PURPOSE: This study aimed to explore daptomycin combined with fosfomycin or rifampin against the planktonic and adherent linezolid-resistant isolates of Enterococcus faecalis. METHODOLOGY: Four linezolid-resistant and four linezolid-sensitive isolates of E. faecalis which formed biofilms were collected for this study. Biofilm biomasses were detected by crystal violet staining and the adherent cells in the mature biofilms were quantified by c.f.u. determination. RESULTS: Daptomycin alone, or combined with fosfomycin or rifampin (4×MIC) demonstrated bactericidal activities on the planktonic cells, and daptomycin combined with fosfomycin killed more planktonic cells (at least 1-log10 c.f.u. ml-1) than daptomycin or fosfomycin alone. Daptomycin alone (16×MIC) showed anti-biofilm activities against the mature biofilms and bactericidal activities on the adherent cells, while daptomycin combined with fosfomycin (16×MIC) demonstrated significantly more anti-biofilm activities than daptomycin or fosfomycin alone and effectively killed the adherent cells in the mature biofilms. The high concentration of daptomycin (512 mg l-1 ) combined with fosfomycin indicated more bactericidal activities on the adherent cells and more anti-biofilm activities against the mature biofilms than daptomycin 64 mg l-1 (16×MIC) combined with fosfomycin. The addition of rifampin increased the anti-biofilm and bactericidal activities of daptomycin against the mature biofilms and the adherent cells of two isolates, however, which was not observed in other isolates. CONCLUSIONS: Daptomycin combined with fosfomycin demonstrated better effect on the planktonic and adherent linezolid-resistant isolates of E. faecalis than daptomycin or fosfomycin alone. The role of rifampin in the treatment of E. faecalis isolates is discrepant and needs more studies.


Assuntos
Antibacterianos/farmacologia , Aderência Bacteriana/efeitos dos fármacos , Daptomicina/farmacologia , Enterococcus faecalis/efeitos dos fármacos , Fosfomicina/farmacologia , Linezolida/farmacologia , Rifampina/farmacologia , Biofilmes/efeitos dos fármacos , Linhagem Celular , Farmacorresistência Bacteriana , Enterococcus faecalis/fisiologia , Infecções por Bactérias Gram-Positivas/microbiologia , Humanos , Testes de Sensibilidade Microbiana , Plâncton/efeitos dos fármacos , Plâncton/fisiologia
18.
Molecules ; 24(6)2019 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-30884874

RESUMO

Biofilm, naturally formed by microorganisms as integrated surface-bound communities, is one of the reasons for the development of antimicrobial resistance. Haemophilus spp. are common and representative opportunistic Gram-negative rods forming from the upper respiratory tract microbiota. The aim of this paper was to evaluate the influence of thiazolidine-2,4-dionebased azolidine and chlorophenylthiosemicarbazone hybrids against both planktonic and biofilm-forming Haemophilus spp. cells. The in vitro activity against planktonic and biofilm-forming cells of the tested compounds were evaluated by using the broth microdilution method. These activities were detected against reference and clinical strains of Haemophilus spp. on the basis of MICs (minimal inhibitory concentrations) and MBICs (minimal biofilm inhibitory concentrations). In addition, anti-adhesive properties of these compounds were examined. The target compounds showed potential activity against planktonic cells with MIC = 62.5⁻500 mg/L and biofilm-forming cells with MBIC = 62.5⁻1000 mg/L. The observed anti-adhesive properties of the tested compounds were reversible during long-term incubation in a lower concentration of compounds.


Assuntos
Antibacterianos/química , Biofilmes/efeitos dos fármacos , Haemophilus/efeitos dos fármacos , Tiossemicarbazonas/química , Antibacterianos/farmacologia , Biofilmes/crescimento & desenvolvimento , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/patogenicidade , Haemophilus/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Plâncton/efeitos dos fármacos , Tiazolidinedionas/química , Tiazolidinedionas/farmacologia , Tiossemicarbazonas/farmacologia
19.
Arch Microbiol ; 201(6): 747-755, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30838426

RESUMO

The present work aimed at studying physiological properties of Pseudomonas aeruginosa cells actively detached from biofilm formed on stainless steel and comparing them with their planktonic counterparts as a function of growth temperature (20 °C and 37 °C). The susceptibility of P. aeruginosa cells to benzalkonium chloride (BAC) was studied. Furthermore, the effect of BAC on the cell membrane integrity and the role of the cell membrane fluidity in the cell-scale-resistance mechanism were investigated. Our results showed that actively detached biofilm cells were more susceptible to BAC treatment than planktonic ones. A greater leakage of intracellular potassium after BAC addition was observed in actively detached biofilm cells, which reflects their membrane vulnerability. The rise of the growth temperature from 20 to 37 °C increased the membrane rigidity of planktonic cells comparatively to their actively detached biofilm ones. Under experimental conditions developed in this work, our data highlighted that actively biofilm-detached and planktonic P. aeruginosa cells have distinguishable phenotypes.


Assuntos
Antibacterianos/farmacologia , Compostos de Benzalcônio/farmacologia , Biofilmes/efeitos dos fármacos , Pseudomonas aeruginosa/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Membrana Celular/efeitos dos fármacos , Farmacorresistência Bacteriana , Plâncton/efeitos dos fármacos , Pseudomonas aeruginosa/fisiologia , Aço Inoxidável/análise , Temperatura
20.
Water Sci Technol ; 79(3): 526-536, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30924807

RESUMO

A model cooling tower system was experimentally seeded with Legionella pneumophila and real industrial cooling tower (CT) water has been run at the closest to full-scale system operating conditions. The water/biofilm samples were taken from the model system monthly, and the effectiveness of the different concentrations of Chloramine T trihydrate biocide was evaluated in terms of its ability to control both planktonic/sessile microbial populations. Although Chloramine T is a recommended commercial formulation for disinfecting CTs, there is a lack of published data on the efficacy of this compound against both planktonic and sessile populations in the cooling tower. Biocide response in both sessile/planktonic bacteria counts varied according to months. Tested biocide concentrations provided the clean tower conditions by reducing the concentration of heterotrophic plate count (HPC) below <104 cfu mL-1, L. pneumophila <10 cfu mL-1 and of adenosine triphosphate (ATP) values <300 relative light units (RLU), after 1, 3 and 24 h of exposure, during a 6-month period. There were no statistically significant differences in efficacy between concentrations in terms of reduction in the number of bacteria, decrease in ATP value and viability. The results revealed that Chloramine T can effectively control biofouling in cooling systems according to the limit values of the successful control program.


Assuntos
Cloraminas/toxicidade , Desinfetantes/toxicidade , Plâncton/efeitos dos fármacos , Compostos de Tosil/toxicidade , Microbiologia da Água , Purificação da Água/métodos , Bactérias/efeitos dos fármacos , Desinfecção/métodos , Legionella , Plâncton/fisiologia
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