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1.
Arq Neuropsiquiatr ; 81(11): 956-960, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-38035580

RESUMEN

BACKGROUND: The perception of family support in chronic disease can be relevant. OBJECTIVE: To assess the perception of family support in adult patients with epilepsy (PWEs) and relate it to quality of life (QoL) and clinical aspects. METHODS: Data from the Perceived Family Support Inventory (IPFS) of 130 PWEs were related to the clinical variables, QOLIE-31 scores, and the Neurological Disorders Depression Inventory for Epilepsy (NDDI-E) with statistical tests, with p < 0.05. RESULTS: The mean age was 49.9 ± 17.2 years, and the duration of epilepsy was 20.8 ± 15.4 years. The presence of depression (scores ≥ 15) was associated with lower family support. Being married and non-occurrence of depression were the variables associated with a higher IPFS score (R = 0.2112), in the multiple linear regression. CONCLUSION: The perception of greater family support was associated with demographic aspects, the absence of depression, and better QoL. Family relationships may play an essential role in health adjustment behaviors and QoL in epilepsy.


ANTECEDENTES: A percepção do suporte familiar nas doenças crônicas pode ser relevante. OBJETIVO: Avaliar em pacientes adultos com epilepsia (PCE) a percepção do suporte familiar e relacioná-la com os aspectos clínicos e com a qualidade de vida (QV). MéTODOS: Os dados do Inventário de Percepção de Suporte Familiar (IPSF) de 130 PCE foram relacionados com as variáveis clínicas, os escores do QOLIE-31 e com o Neurological Disorders Depression Inventory for Epilepsy (NDDI-E), com testes estatísticos, com p < 0.05. RESULTADOS: A idade média foi 49.9 ± 17.2 anos e o tempo de epilepsia foi de 20.8 ± 15.4 anos. Escores ≥ 15 no NDDI-E (presença de depressão) associaram-se a menor suporte familiar. Ser casado e não ter depressão são as variáveis associadas a maiores escores no IPSF (R = 0.2112), na regressão linear múltipla. CONCLUSãO: A percepção de maior suporte familiar associou-se à aspectos demográficos, a ausência de depressão e a melhor QV. As relações familiares podem ter papel essencial nos comportamentos de ajustamento na saúde e na QV na epilepsia.


Asunto(s)
Epilepsia , Calidad de Vida , Humanos , Adulto , Persona de Mediana Edad , Anciano , Depresión , Apoyo Familiar , Modelos Lineales
2.
RSC Adv ; 13(47): 33424-33429, 2023 Nov 07.
Artículo en Inglés | MEDLINE | ID: mdl-38025875

RESUMEN

This work presents a biosensor based on core-shell nanostructure formed by zinc oxide (ZnO) nanoparticles coated with gold (Au). The core-shell nanostructure served as a support for the immobilisation of tyrosinase on screen-printed carbon electrodes to measure dopamine using differential pulse voltammetry. While ZnO is a semiconductor with good electrical conductivity, Au offers high stability and biocompatibility, which is beneficial for maintaining enzyme activity. Atomic force microscopy (ATM), ultraviolet (UV) and infrared (IR) spectroscopy measurements confirmed that the core-shell was successfully formed. The biosensor comprising of ZnO@Au core-shell nanostructures with immobilised tyrosinase allowed the detection of dopamine in real samples with remarkable selectivity and accuracy with a relative error of 3.8%. The limit of detection and dynamic range of the biosensor for dopamine in real samples were 86 nmol L-1 and 0.1 to 500 µmol L-1, respectively. Thus, the results indicate that the proposed miniaturized biosensor device is promising for the monitoring of dopamine in real samples and can be used for disease diagnosis and prognosis. Furthermore, the reported electrochemical biosensor is of low-cost when compared to conventional techniques.

3.
An Acad Bras Cienc ; 95(suppl 1): e20220624, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37493695

RESUMEN

SARS-CoV-2 is a matter of concern. Here, biosensors were prepared using iron magnetic nanoparticles containing antibodies against the receptor binding domain (RBD) of the spike protein. Antibodies were adsorbed to nanoparticles in three configurations, including direct adsorption without functionalization (DANPs). Nanoparticles were added to a glassy carbon electrode and connected to an electrochemical cell. Electrochemical impedance spectroscopy and ELISA experiments indicated that antibodies were desorbed from the DANPs upon the addition of the RBD. DANPs-based biosensors produced linear curves with decreasing charge transfer resistance due to the removal of antibodies. Thus, a detection method can be based on antibody desorption.


Asunto(s)
COVID-19 , Nanopartículas de Magnetita , Humanos , SARS-CoV-2 , Espectroscopía Dieléctrica , Glicoproteína de la Espiga del Coronavirus , Hierro
4.
Environ Technol ; 44(3): 334-341, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34407726

RESUMEN

This work shows the efficiency of wash waters from lipopeptide production as a remediation strategy to treat urban water samples contaminated with p-cresol. The harvesting step in surfactin production involved a centrifugation step, generating a major soluble fraction and a fraction that is adsorbed to the biomass. The adsorbed fraction was recovered by washing steps. These wash waters containing lipopeptides (mostly surfactins), were successfully used to adsorb and solubilize p-cresol. The method of decontamination applied to an artificially contaminated natural water was monitored using a biosensor based on laccase/magnetic nanoparticles. Given the amount of surfactin within the wash water, the removal of p-cresol from artificially contaminated water was approximately 46.0%. This result confirms the successful and sustainable application of surfactin-rich wash waters to remove p-cresol from artificially contaminated natural water. The adsorption mechanism is potentially based on a multi-layer adsorption process, considering Langmuir and Freundlich adsorption isotherms.


Asunto(s)
Lipopéptidos , Contaminantes Químicos del Agua , Cresoles , Adsorción , Agua
5.
J Am Chem Soc ; 144(21): 9372-9379, 2022 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-35583956

RESUMEN

Harmful cyanobacterial blooms (cyanoHABs) cause recurrent toxic events in global watersheds. Although public health agencies monitor the causal toxins of most cyanoHABs and scientists in the field continue developing precise detection and prediction tools, the potent anticholinesterase neurotoxin, guanitoxin, is not presently environmentally monitored. This is largely due to its incompatibility with widely employed analytical methods and instability in the environment, despite guanitoxin being among the most lethal cyanotoxins. Here, we describe the guanitoxin biosynthesis gene cluster and its rigorously characterized nine-step metabolic pathway from l-arginine in the cyanobacterium Sphaerospermopsis torques-reginae ITEP-024. Through environmental sequencing data sets, guanitoxin (gnt) biosynthetic genes are repeatedly detected and expressed in municipal freshwater bodies that have undergone past toxic events. Knowledge of the genetic basis of guanitoxin biosynthesis now allows for environmental, biosynthetic gene monitoring to establish the global scope of this neurotoxic organophosphate.


Asunto(s)
Cianobacterias , Cianobacterias/genética , Cianobacterias/metabolismo , Toxinas de Cianobacterias , Monitoreo del Ambiente , Agua Dulce , Familia de Multigenes
6.
Environ Sci Pollut Res Int ; 29(6): 8767-8778, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-34491500

RESUMEN

Microcystin, a cyanotoxin produced by Microcystis aeruginosa growing in eutrophic waters, can promote liver tumors in people ingesting contaminated water. To date, water treatment systems have not been effective in removing or degrading these cyanotoxins. In this work, we investigated the inhibitory activity of surfactants on the growth of M. aeruginosa and their application to extract the intracellular produced cyanotoxins. The experiments involving growth inhibition and extraction of cyanotoxins were carried out using the non-biodegradable surfactant cetyl trimethyl ammonium bromide (CTAB) in addition to other biodegradable surfactants. These were Tween 80 and surfactants derived from amino acids and peptides, respectively, from arginine, SDA, and hydrolyzed peptone, SDP. We demonstrated that the tested surfactants could be used to inhibit the growth of M. aeruginosa. At this point, CTAB and SDA proved to be the most competent surfactants in reducing cyanobacterial growth. Moreover, microcystins have been successfully removed from the water employing a cloud point extraction protocol based on the use of these surfactants and ammonium sulfate.


Asunto(s)
Microcistinas , Microcystis , Aminoácidos , Toxinas de Cianobacterias , Humanos
7.
World J Microbiol Biotechnol ; 37(7): 123, 2021 Jun 23.
Artículo en Inglés | MEDLINE | ID: mdl-34160683

RESUMEN

Lipopeptides are important secondary metabolites produced by microbes. They find applications in environmental decontamination and in the chemical, pharmaceutical and food industries. However, their production is expensive. In the present work we propose three strategies to lower the production costs of surfactin. First, the coproduction of surfactin and arginase in a single growth. Second, extract the fraction of surfactin that adsorbs to the biomass and is removed from the growth medium through centrifugation. Third, use microbial biomass for the remediation of organic and inorganic contaminants. The coproduction of surfactin and arginase was evaluated by factorial design experiments using the LB medium supplemented with arginine. The best conditions for surfactin production were 22 h of growth at 37 °C using LB supplemented with arginine 7.3 g/L. Almost similar conditions were found to produce highest levels of arginase, 24 h and 6.45 g/L arginine. Decontamination of phenol and copper from artificial samples was attained by treatment with residues from lipopeptide production. Thus, cell suspensions and wash-waters used to extract surfactin from the biomass. Cell suspensions were used to successfully remove hydroquinone. Cell suspensions and wash-waters containing surfactin were successfully used to recover copper from solution. Specific monitoring methods were used for phenol and metal solutions, respectively a biosensor based on tyrosinase and either atomic absorption flame ionization spectrometry or absorbance coupled to the Arduino™ platform. Therefore, we report three alternative strategies to lower the production costs in lipopeptide production, which include the effective recovery of copper and phenol from contaminated waters using residues from surfactin production. Sustainable and profitable production of surfactin can be achieved by a coproduction strategy of lipopeptides and enzymes. Lipopeptides are collected in the supernatant and enzymes in the biomass. In addition, lipopeptides that coprecipitate with biomass can be recovered by washing. Lipopeptide wash-waters find applications in remediation and cells can also be used for environmental decontamination.


Asunto(s)
Arginasa/biosíntesis , Bacillus/enzimología , Bacillus/crecimiento & desarrollo , Bacillus/metabolismo , Lipopéptidos/biosíntesis , Péptidos Cíclicos/biosíntesis , Bacillus/genética , Proteínas Bacterianas/biosíntesis , Biomasa , Reactores Biológicos , Cobre/metabolismo , Medios de Cultivo , ADN Bacteriano , Microbiología Ambiental , Restauración y Remediación Ambiental , Hidroquinonas/metabolismo , Fenol/metabolismo
8.
Indian J Dent Res ; 31(4): 615-620, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33107465

RESUMEN

Currently, there is a growing interest in studying systemic conditions associated with periodontal disease such as autoimmune disorders. Periodontal disease is a destructive inflammatory disease of the dental supporting tissues. The microorganisms associated with periodontal disease constitute diverse species that can colonize the oral cavity and influence the emergence or evolution of autoimmunity, characterized by a breakdown in the mechanisms of tolerance to self-antigens. Here, we reviewed and discussed a possible correlation between periodontal disease and autoimmunity, placing periodontal-pathogenic microorganisms as orchestrators of these pathological conditions.


Asunto(s)
Enfermedades Autoinmunes , Enfermedades Periodontales , Autoinmunidad , Humanos
9.
Amino Acids ; 52(1): 25-33, 2020 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31781907

RESUMEN

Surfactins are important lipopeptides produced by Bacillus subtilis that present strong surface activity. These biosurfactants find applications in various fields, from environmental remediation to medicine. The use of surfactins in remediation is hampered by production costs; the medical applications are also reframed because of the hemolytic activity of the cyclic peptide. To reduce costs and working time, the present work focused on the design, chemical synthesis and characterization of simple linear variants of surfactins having only L-amino acids and lauric acid at the N-terminal. Carboxyl-free and amidated analogues with negative, null and positive net charges at physiological pH were successfully obtained. The synthetic isoforms of surfactins showed high surface activity and ability to inhibit both growth and adhesion of Streptococcus mutans cells. Therefore, these properties make these low-cost synthetic peptides relevant and promising new compounds for science, industry and, mainly, dental care.


Asunto(s)
Aminoácidos/química , Ácidos Láuricos/química , Lipopéptidos/química , Aminoácidos/síntesis química , Aminoácidos/farmacología , Bacillus subtilis/química , Atención Odontológica , Humanos , Concentración de Iones de Hidrógeno , Ácidos Láuricos/síntesis química , Ácidos Láuricos/farmacología , Lipopéptidos/síntesis química , Lipopéptidos/farmacología , Streptococcus mutans/efectos de los fármacos , Tensoactivos/síntesis química , Tensoactivos/química
10.
Amino Acids ; 51(8): 1233-1240, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31197572

RESUMEN

The aim of this study was to evaluate the effect of spreading the lipopeptide surfactin, for short time (10/20 s), on dentin wettability. Study groups were surfactin: 2.8; 1.4; 0.7; 0.35; and 0.175 mg/mL and a control group that received no treatment. Dentin discs (4 mm height) were prepared and polished with 600-grit SiC paper. Contact angle determinations were carried out after microbrush spreading of surfactin on dentin specimens for, respectively, 10 and 20 s. Excess liquid was removed, and after 60 s, the specimens were analyzed in a goniometer using the sessile drop method to measure the contact angle. Results were analyzed by two-way ANOVA (concentration × time) and t student, with α = 0.05. Lower contact angles were obtained for surfactin (0.7 mg/mL) spread for 10 s. However, no statistical difference was observed for surfactin (2.8 mg/mL) applied during 20 s. Higher contact angles were observed for surfactin (0.7 mg/mL) spread for 20 s. In conclusion, dentin wettability is dependent on spreading time and surfactin concentration.


Asunto(s)
Dentina/química , Lipopéptidos/administración & dosificación , Péptidos Cíclicos/administración & dosificación , Diente/química , Humectabilidad/efectos de los fármacos , Dentina/efectos de los fármacos , Humanos , Ensayo de Materiales , Propiedades de Superficie
11.
Biotechnol J ; 14(4): e1800314, 2019 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-30430761

RESUMEN

Lipopeptides, such as surfactins are important biosurfactants produced by Bacillus sp. that find applications in many areas (environment, medicine, and food industries). Giving their importance, the use of simple detection methods will facilitate screening and quantification. In the present work, the authors describe a completely automated workflow for the screening of lipopeptide-producing strains, including quantification. First, isolated colonies from environmental samples are automatically picked and inoculated in 96 wells growth plate. After overnight incubation, surfactin produced in the broth is quantified, using a new sensitive fluorescent method. The method uses fluorescein (FL), which is an anionic dye at neutral to alkaline pH and forms a stable complex with the cationic surfactant cetylpiridinium chloride (CPC), quenching fluorescence. Upon addition of surfactin or other lipopeptides, fluorescein is released from the CPC-FL complex and quantified. The robustness of this method is assessed by comparing the quantification results to those conventionally measured by RP-UPLC and the results of strain screening are confirmed by MALDI-ToF analysis. The authors report for the first time the successful application of this analytical method for high-throughput screening of novel lipopeptide-producing strains.


Asunto(s)
Cetilpiridinio/aislamiento & purificación , Lipopéptidos/química , Tensoactivos/aislamiento & purificación , Bacillus/química , Bacillus/genética , Cetilpiridinio/química , Fluorescencia , Lipopéptidos/biosíntesis , Lipopéptidos/aislamiento & purificación , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Tensoactivos/química
12.
World J Microbiol Biotechnol ; 34(6): 86, 2018 Jun 06.
Artículo en Inglés | MEDLINE | ID: mdl-29876752

RESUMEN

The oral pathogen Streptococcus mutans is involved in tooth decay by a process that initiates with biofilm adhesion and caries development. The presence of other microbes such as Candida albicans may worsen the demineralization process. Since both microbes are virulent to the host and will proliferate under specific host immune deficiencies and systemic diseases, it is important to study antimicrobial substances and their effects on both pathogens. There are several antiseptic agents used to reduce plaque biofilm and its outcome (dental caries and/or periodontal disease). However, some of these have undesired effects. In the current study we investigated the antimicrobial and anti-adhesion properties of micellar solutions of surfactants and the plant natural product terpinen-4-ol (TP). The results revealed an increase in antimicrobial properties of the synthetic surfactants, cetylpyridinium chloride (CPC) and cetyltrimethylammonium bromide (CTAB), when mixed with TP. In addition, although surfactin, a biosurfactant, has little antimicrobial activity, it was demonstrated that it enhanced the effect of TP both as antimicrobial and anti-adhesion compound. Surfactin and the synthetic surfactants promote the antimicrobial activity of TP against S. mutans, the causal agent of tooth decay, suggesting specificity for membrane interactions that may be facilitated by surfactants. This is the first report on the successful use of surfactin in association with TP to inhibit the growth and adhesion of microbial pathogens. Surfactin has other beneficial properties besides being biodegradable, it has antiviral and anti-mycoplasma activities in addition to adjuvant properties and encapsulating capacity at low concentration.


Asunto(s)
Antibacterianos/farmacología , Adhesión Bacteriana/efectos de los fármacos , Compuestos de Cetrimonio/farmacología , Cetilpiridinio/farmacología , Streptococcus mutans/efectos de los fármacos , Tensoactivos/farmacología , Terpenos/farmacología , Biopelículas , Candida albicans/efectos de los fármacos , Cetrimonio , Caries Dental/microbiología , Pruebas Antimicrobianas de Difusión por Disco , Humanos , Streptococcus mutans/fisiología
13.
ACS Chem Biol ; 12(3): 769-778, 2017 03 17.
Artículo en Inglés | MEDLINE | ID: mdl-28085246

RESUMEN

Cyanobacteria produce a broad range of natural products, many of which are potent protease inhibitors. Biosynthetic gene clusters encoding the production of novel protease inhibitors belonging to the spumigin and anabaenopeptin family of nonribosomal peptides were identified in the genome of the bloom-forming cyanobacterium Sphaerospermopsis torques-reginae ITEP-024. The genetic architecture and gene organization of both nonribosomal peptide biosynthetic clusters were compared in parallel with their chemical structure variations obtained by liquid chromatography (LC-MS/MS). The spumigin (spu) and anabaenopeptin (apt) gene clusters are colocated in the genomes of S. torques-reginae ITEP-024 and Nodularia spumigena CCY9414 and separated by a 12 kb region containing genes encoding a patatin-like phospholipase, l-homophenylalanine (l-Hph) biosynthetic enzymes, and four hypothetical proteins. hphABCD gene cluster encoding the production of l-Hph was linked to all eight apt gene clusters investigated here. We suggest that while the HphABCD enzymes are an integral part of the anabaenopeptin biosynthetic pathway, they provide substrates for the biosynthesis of both anabaenopeptins and spumigins. The organization of the spu and apt suggests a plausible model for the biosynthesis of the 4-(4-hydroxyphenyl)-2-acid (Hpoba) precursor of spumigin variants in S. torques-reginae ITEP-024 based on the acceptable substrates of HphABCD enzymes.


Asunto(s)
Cianobacterias/metabolismo , Familia de Multigenes , Oligopéptidos/biosíntesis , Péptidos Cíclicos/química , Cianobacterias/genética , Filogenia
14.
Can J Microbiol ; 63(1): 46-60, 2017 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-27912317

RESUMEN

Biosurfactants are important in many areas; however, costs impede large-scale production. This work aimed to develop a global sustainable strategy for the production of biosurfactants by a novel strain of Bacillus amyloliquefaciens. Initially, Bacillus sp. strain 0G was renamed B. amyloliquefaciens subsp. plantarum (syn. Bacillus velezensis) after analysis of the gyrA and gyrB DNA sequences. Growth in modified Landy's medium produced 3 main recoverable metabolites: surfactin, fengycin, and acetoin, which promote plant growth. Cultivation was studied in the presence of renewable carbon (as glycerol) and nitrogen (as arginine) sources. While diverse kinetics of acetoin production were observed in different media, similar yields (6-8 g·L-1) were obtained after 72 h of growth. Glycerol increased surfactin-specific production, while arginine increased the yields of surfactin and fengycin and increased biomass significantly. The specific production of fengycin increased ∼10 times, possibly due to a connecting pathway involving arginine and ornithine. Adding value to crude extracts and biomass, both were shown to be useful, respectively, for the removal of p-xylene from contaminated water and for biodiesel production, yielding ∼70 mg·g-1 cells and glycerol, which could be recycled in novel media. This is the first study considering circular bioeconomy to lower the production costs of biosurfactants by valorisation of both microbial cells and their primary and secondary metabolites.


Asunto(s)
Bacillus amyloliquefaciens/metabolismo , Biocombustibles/análisis , Medios de Cultivo/metabolismo , Contaminantes Químicos del Agua/metabolismo , Xilenos/metabolismo , Bacillus amyloliquefaciens/genética , Bacillus amyloliquefaciens/crecimiento & desarrollo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Biodegradación Ambiental , Biomasa , Glicerol/metabolismo , Lipopéptidos/metabolismo , Péptidos Cíclicos/metabolismo
15.
Microbiol Res ; 166(3): 161-75, 2011 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-20630723

RESUMEN

Cyanobacterial strains isolated from terrestrial and freshwater habitats in Brazil were evaluated for their antimicrobial and siderophore activities. Metabolites of fifty isolates were extracted from the supernatant culture media and cells using ethyl acetate and methanol, respectively. The extracts of 24 isolates showed antimicrobial activity against several pathogenic bacteria and one yeast. These active extracts were characterized by Q-TOF/MS. The cyanobacterial strains Cylindrospermopsis raciborskii 339-T3, Synechococcus elongatus PCC7942, Microcystis aeruginosa NPCD-1, M. panniformis SCP702 and Fischerella sp. CENA19 provided the most active extracts. The 50 cyanobacterial strains were also screened for the presence of non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) genes and microcystin production. Putative fragment genes coding for NRPS adenylation domains and PKS keto-synthase domains were successfully PCR amplified from 92% and 80% of cyanobacterial strains, respectively. The potential therapeutical compounds siderophores were detected in five cyanobacterial isolates. Microcystin production was detected by ELISA test in 26% of the isolates. Further a protease inhibitor substance was detected by LC-MS/MS in the M. aeruginosa NPLJ-4 extract and the presence of aeruginosin and cyanopeptolin was confirmed by PCR amplification using specific primers, and sequenced. This screening study showed that Brazilian cyanobacterial isolates are a rich source of natural products with potential for pharmacological and biotechnological applications.


Asunto(s)
Antiinfecciosos/farmacología , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/farmacología , Cianobacterias/metabolismo , Sideróforos/metabolismo , Antiinfecciosos/aislamiento & purificación , Antiinfecciosos/metabolismo , Proteínas Bacterianas/química , Brasil , Cianobacterias/química , Cianobacterias/genética , Cianobacterias/aislamiento & purificación , Descubrimiento de Drogas , Ensayo de Inmunoadsorción Enzimática , Variación Genética , Espectrometría de Masas , Pruebas de Sensibilidad Microbiana , Microcistinas/biosíntesis , Péptido Sintasas/genética , Sintasas Poliquetidas/genética , Sintasas Poliquetidas/metabolismo , Reacción en Cadena de la Polimerasa , Inhibidores de Proteasas/análisis , Inhibidores de Proteasas/aislamiento & purificación , Sideróforos/aislamiento & purificación
16.
Arch Microbiol ; 190(6): 611-22, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18654762

RESUMEN

Lipopeptides produced by Bacillus subtilis are known for their high antifungal activity. The aim of this paper is to show that at high concentration they can damage the surface ultra-structure of bacterial cells. A lipopeptide extract containing iturin and surfactin (5 mg mL(-1)) was prepared after isolation from B. subtilis (strain OG) by solid phase extraction. Analysis by atomic force microscope (AFM) showed that upon evaporation, lipopeptides form large aggregates (0.1-0.2 microm(2)) on the substrates silicon and mica. When the same solution is incubated with fungi and bacteria and the system is allowed to evaporate, dramatic changes are observed on the cells. AFM micrographs show disintegration of the hyphae of Phomopsis phaseoli and the cell walls of Xanthomonas campestris and X. axonopodis. Collapses to fungal and bacterial cells may be a result of formation of pores triggered by micelles and lamellar structures, which are formed above the critical micelar concentration of lipopeptides. As observed for P. phaseoli, the process involves binding, solubilization, and formation of novel structures in which cell wall components are solubilized within lipopeptide vesicles. This is the first report presenting evidences that vesicles of uncharged and negatively charged lipopeptides can alter the morphology of gram-negative bacteria.


Asunto(s)
Antibacterianos/farmacología , Antifúngicos/farmacología , Bacillus subtilis/metabolismo , Pared Celular/efectos de los fármacos , Lipopéptidos/farmacología , Bacillus subtilis/química , Bacillus subtilis/clasificación , Pared Celular/ultraestructura , Bacterias Gramnegativas/efectos de los fármacos , Bacterias Gramnegativas/ultraestructura , Lipopéptidos/ultraestructura , Microscopía de Fuerza Atómica , Filogenia , Xanthomonas campestris/efectos de los fármacos
17.
Microsc Res Tech ; 71(2): 112-8, 2008 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-17943987

RESUMEN

Connectivity of the glycocalyx covering of small communities of Acidithiobacillus ferrooxidans bacteria deposited on hydrophilic mica plates was imaged by atomic force microscopy. When part of the coverage was removed by water rinsing, an insoluble structure formed by corrals surrounding each individual bacterium was observed. A collective ring structure with clustered bacteria (>or=3) was observed, which indicates that the bacteria perceived the neighborhood in order to grow a protective structure that results in smaller production of exopolysaccharides material. The most surprising aspect of these collective corral structures was that they occur at a low bacterial cell density. The deposited layers were also analyzed by confocal Raman microscopy and shown to contain polysaccharides, protein, and glucoronic acid.


Asunto(s)
Acidithiobacillus/fisiología , Glicocálix/química , Glicocálix/microbiología , Microscopía de Fuerza Atómica/métodos , Percepción de Quorum/fisiología , Proteínas Bacterianas/análisis , Ácido Glucárico/análisis , Microscopía Confocal , Polisacáridos Bacterianos/análisis
18.
Microbiol Res ; 161(3): 263-72, 2006.
Artículo en Inglés | MEDLINE | ID: mdl-16765843

RESUMEN

Xylella fastidiosa is a pathogenic bacterium found in several plants. These bacteria secrete extracellular proteases into the culture broth as visualized in sodium-dodecyl-sulfate polyacrylamide activity gels containing gelatin as a copolymerized substrate. Three major protein bands were produced by the citrus strain with molar masses (MM) of 122, 84 and 65 kDa. Grape strain 9,713 produced two bands of approximately 84 and 64 kDa. These organisms produced zones of hydrolysis in agar plates amended with gelatin, casein and hemoglobin. Gelatin was the best substrate for these proteases. Sodium dodecyl sulfate-polyacrylamide electrophoresis (SDS-PAGE) activity gel indicated that the protease of Xylella fastidiosa from citrus and grape were completely inhibited by PMSF and partially inhibited by EDTA. The optimal temperature for protease activity was 30 degrees C with an optimal pH of 7.0. Among the proteolytic enzymes secreted by the phytopathogen, chitinase and beta-1,3-glucanase activities were also detected in cultures of Xylella fastidiosa (citrus). From these results, it is suggested that proteases produced by strains of Xylella fastidiosa from citrus and grape, belong to the serine- and metallo-protease group, respectively.


Asunto(s)
Péptido Hidrolasas/metabolismo , Xylella/metabolismo , Quitinasas/metabolismo , Citrus/microbiología , Ácido Edético/farmacología , Glucano 1,3-beta-Glucosidasa/metabolismo , Concentración de Iones de Hidrógeno , Peso Molecular , Péptido Hidrolasas/química , Péptido Hidrolasas/efectos de los fármacos , Fluoruro de Fenilmetilsulfonilo/farmacología , Enfermedades de las Plantas/microbiología , Especificidad de la Especie , Especificidad por Sustrato , Temperatura , Vitis/microbiología , Xylella/crecimiento & desarrollo
19.
Genet. mol. biol ; 29(1): 137-141, 2006. tab
Artículo en Inglés | LILACS | ID: lil-424750

RESUMEN

Bacterial production of siderophores may involve specific genes related to nonribosomal peptide and polyketide biosynthesis, which have not been fully identified in the genome of Xylella fastidiosa strain 9a5c. However, a search for siderophore-related genes in strain 9a5c indicated five membrane receptors, including siderophore, ferrichrome-iron and hemin receptors. All these biomolecules are thought to be associated with iron transport and utilization. Eighty isolates obtained from citrus orchards containing trees that developed citrus variegated chlorosis (CVC) were screened for siderophore production. The results demonstrated that only 10 of the isolates did not produce siderophores. Additional strains obtained from coffee, almond, mulberry, elm, ragweed, periwinkle and grape also infected by X. fastidiosa were also shown by the chromeazurol bioassay to produce siderophores. In order to correlate siderophore production with the presence of siderophore-related genes, a polymerase chain reaction (PCR) was developed using specific primers for the catechol-type ferric enterobactin receptor (pfeA) and the hydroxamate-type ferrisiderophore receptor (fiuA) genes of strain 9a5c. The PCR results confirmed our hypothesis by demonstrating that amplification products were detected in all strains except for those isolates that did not produce siderophores.


Asunto(s)
Animales , Complejos Multienzimáticos , Biosíntesis de Péptidos Independientes de Ácidos Nucleicos , Xylella/genética , Enfermedades de las Plantas/microbiología , Enterobactina , Bacterias Gramnegativas , Reacción en Cadena de la Polimerasa
20.
Microbiol Res ; 159(4): 425-37, 2004.
Artículo en Inglés | MEDLINE | ID: mdl-15646388

RESUMEN

The genomes of the plant pathogens Xanthomonas axonopodis (Xac) and Xanthomonas campestris (Xcc) were analysed with the aim of deducing their ability to produce nonribosomal peptides. Nonribosomal peptide synthetase (NRPS) genes were identified in two separate loci of Xac. While the genes of locus 1 are common to both strains, locus 2 was only found in Xac. Dissection and phylogenetic analysis of the condensation and thioesterase domains of the NRPSs of loci 1 and 2 of Xac revealed homology, respectively, with siderophore and lipopeptide synthetases. Further analysis of locus 1 revealed genes related to polyketide and polyamine biosynthesis that could be involved in the assembly of substrates for siderophore biosynthesis in both strains. In vitro production of siderophores by both Xac and Xcc was confirmed. Since bacterial siderophores and lipopeptides can be pathogenic and are typically produced nonribosomally, these results suggest that the identified genes could be involved in phytotoxin production.


Asunto(s)
Proteínas Bacterianas/biosíntesis , Lipoproteínas/biosíntesis , Biosíntesis de Péptidos Independientes de Ácidos Nucleicos , Péptido Sintasas/genética , Sideróforos/biosíntesis , Xanthomonas/genética , Proteínas Bacterianas/genética , Hierro/metabolismo , Lipoproteínas/genética , Macrólidos/metabolismo , Estructura Molecular , Filogenia , Poliaminas/metabolismo , Estructura Terciaria de Proteína , Homología de Secuencia , Sideróforos/genética , Xanthomonas/enzimología
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