Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 62
Filtrar
Más filtros

Bases de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
J Korean Med Sci ; 38(10): e73, 2023 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-36918027

RESUMEN

BACKGROUND: The epidemiology of pathogenic bacteria varies according to the socioeconomic status and antimicrobial resistance status. However, longitudinal epidemiological studies to evaluate the changes in species distribution and antimicrobial susceptibility of pathogenic bacteria nationwide are lacking. We retrospectively investigated the nationwide trends in species distribution and antimicrobial susceptibility of pathogenic bacteria over the last 20 years in Korea. METHODS: From 1997 to 2016, annual cumulative antimicrobial susceptibility and species distribution data were collected from 12 university hospitals in five provinces and four metropolitan cities in South Korea. RESULTS: The prevalence of Staphylococcus aureus was the highest (13.1%) until 2012 but decreased to 10.3% in 2016, consistent with the decrease in oxacillin resistance from 76.1% in 2008 to 62.5% in 2016. While the cefotaxime resistance of Escherichia coli increased from 9.0% in 1997 to 34.2% in 2016, E. coli became the most common species since 2013, accounting for 14.5% of all isolates in 2016. Pseudomonas aeruginosa and Acinetobacter baumannii rose to third and fifth places in 2008 and 2010, respectively, while imipenem resistance increased from 13.9% to 30.8% and 0.7% to 73.5% during the study period, respectively. Streptococcus agalactiae became the most common pathogenic streptococcal species in 2016, as the prevalence of Streptococcus pneumoniae decreased since 2010. During the same period, pneumococcal penicillin susceptibility decreased to 79.0%, and levofloxacin susceptibility of S. agalactiae decreased to 77.1% in 2016. CONCLUSION: The epidemiology of pathogenic bacteria has changed significantly over the past 20 years according to trends in antimicrobial resistance in Korea. Efforts to confine antimicrobial resistance would change the epidemiology of pathogenic bacteria and, consequently, the diagnosis and treatment of infectious diseases.


Asunto(s)
Antibacterianos , Escherichia coli , Humanos , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Estudios Retrospectivos , Farmacorresistencia Bacteriana , Bacterias , Pruebas de Sensibilidad Microbiana , Bacterias Gramnegativas
2.
Mil Psychol ; 34(1): 1-11, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-38536245

RESUMEN

The current study examined correlates of life satisfaction among Korean Vietnam War Veterans. The sample included 450 male Veterans from the Korean Vietnam War Veterans Study, surveyed by mail in 2013 (Mean age = 67.4 years old, SD = 3.0). A hierarchical analysis was conducted by entering four blocks of variables: first demographic factors, and then pre-military service, military service, and post-military service variables. Each successive regression analysis showed a significant additional contribution to the variance in life satisfaction. In the final model, Korean Veterans had higher life satisfaction when they were married, had higher monthly income and poorer childhood family environment, appraised their military service in a positive light, and had less stressors after homecoming and better perceived physical health. However, combat exposure and social support after homecoming were not independently associated with life satisfaction in the final model. These results imply that both pre- and post-military service factors, as well as cognitive appraisals of military service, should be considered in understanding the subjective well-being of Korean Vietnam War Veterans in later life.

3.
Bioprocess Biosyst Eng ; 44(4): 891-899, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33486578

RESUMEN

Cadaverine, 1,5-diaminopentane, is one of the most promising chemicals for biobased-polyamide production and it has been successfully produced up to molar concentration. Pyridoxal 5'-phosphate (PLP) is a critical cofactor for inducible lysine decarboxylase (CadA) and is required up to micromolar concentration level. Previously the regeneration of PLP in cadaverine bioconversion has been studied and salvage pathway pyridoxal kinase (PdxY) was successfully introduced; however, this system also required a continuous supply of adenosine 5'-triphosphate (ATP) for PLP regeneration from pyridoxal (PL) which add in cost. Herein, to improve the process further a method of ATP regeneration was established by applying baker's yeast with jhAY strain harboring CadA and PdxY, and demonstrated that providing a moderate amount of adenosine 5'-triphosphate (ATP) with the simple addition of baker's yeast could increase cadaverine production dramatically. After optimization of reaction conditions, such as PL, adenosine 5'-diphosphate, MgCl2, and phosphate buffer, we able to achieve high production (1740 mM, 87% yield) from 2 M L-lysine. Moreover, this approach could give averaged 80.4% of cadaverine yield after three times reactions with baker's yeast and jhAY strain. It is expected that baker's yeast could be applied to other reactions requiring an ATP regeneration system.


Asunto(s)
Adenosina Trifosfato/metabolismo , Cadaverina/química , Escherichia coli/metabolismo , Fosfato de Piridoxal/metabolismo , Saccharomyces cerevisiae , Agar/química , Biotecnología/métodos , Biotransformación , Cadaverina/metabolismo , Carboxiliasas , Fermentación , Microbiología Industrial/instrumentación , Microbiología Industrial/métodos , Lisina/química , Lisina/metabolismo , Polímeros/química , Piridoxal , Regeneración
4.
J Ind Microbiol Biotechnol ; 47(12): 1045-1057, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33259029

RESUMEN

Psychrophilic bacteria, living at low and mild temperatures, can contribute significantly to our understanding of microbial responses to temperature, markedly occurring in the bacterial membrane. Here, a newly isolated strain, Pseudomonas sp. B14-6, was found to dynamically change its unsaturated fatty acid and cyclic fatty acid content depending on temperature which was revealed by phospholipid fatty acid (PLFA) analysis. Genome sequencing yielded the sequences of the genes Δ-9-fatty acid desaturase (desA) and cyclopropane-fatty acid-acyl-phospholipid synthase (cfa). Overexpression of desA in Escherichia coli led to an increase in the levels of unsaturated fatty acids, resulting in decreased membrane hydrophobicity and increased fluidity. Cfa proteins from different species were all found to promote bacterial growth, despite their sequence diversity. In conclusion, PLFA analysis and genome sequencing unraveled the temperature-related behavior of Pseudomonas sp. B14-6 and the functions of two membrane-related enzymes. Our results shed new light on temperature-dependent microbial behaviors and might allow to predict the consequences of global warming on microbial communities.


Asunto(s)
Ácidos Grasos Insaturados , Pseudomonas , Secuencia de Aminoácidos , Bacterias/metabolismo , Secuencia de Bases , Ciclopropanos , Escherichia coli/metabolismo , Ácido Graso Desaturasas/genética , Ácido Graso Desaturasas/metabolismo , Ácido Graso Sintasas/genética , Ácidos Grasos/análisis , Ácidos Grasos Insaturados/metabolismo , Pseudomonas/metabolismo , Temperatura
5.
Int J Syst Evol Microbiol ; 66(7): 2573-2577, 2016 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-27088668

RESUMEN

A Gram-stain-positive, catalase-positive, facultatively anaerobic, non-motile, coryneform bacterium, designated strain 32T, was isolated from a closed pus sample from a patient having finger necrosis in Korea. Strain 32T was considered as representing a novel species according to its initial identification by matrix-assisted laser desorption/ionization-time-of-flight MS. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 32T belonged to the genus Dermabacter and was closely related to Dermabacter hominis DSM 7083T (=ATCC 49369T) (98.34 % similarity). Optimal growth was observed at 30-40 °C and pH 7. Growth occurred in the presence of 0-6 % (w/v) NaCl. Menaquinones MK-8, MK-7 and MK-9 were the major respiratory quinones. The major polar lipids were phosphatidylethanolamine, phosphatidylcholine, glycolipid and two unknown lipids. The major cellular fatty acids were anteiso-C17 : 0, anteiso-C15 : 0, iso-C16 : 0 and iso-C15 : 0. The DNA G+C content of strain 32T was 62.58 mol%, and the mean level of DNA-DNA relatedness between strain 32T and D. hominis ATCC 49369T was 49±1.6 %. Based on the phenotypic and genotypic characteristics, strain 32T is confirmed to represent a novel species of the genus Dermabacter, for which the name Dermabacter jinjuensis sp. nov. is proposed. The type strain is 32T (=NCCP 16133T=DSM 101003T).


Asunto(s)
Actinomycetales/clasificación , Dedos/microbiología , Filogenia , Supuración/microbiología , Actinomycetales/genética , Actinomycetales/aislamiento & purificación , Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano/genética , Ácidos Grasos/química , Dedos/patología , Humanos , Necrosis , Hibridación de Ácido Nucleico , Fosfolípidos/química , ARN Ribosómico 16S/genética , República de Corea , Análisis de Secuencia de ADN , Vitamina K 2/química
6.
J Clin Microbiol ; 51(9): 3063-5, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23784123

RESUMEN

We assessed the accuracy of yeast bloodstream isolate identification performed over a 1-year period at 10 South Korean hospitals, using the matrix-assisted laser desorption ionization-time of flight (MALDI-TOF)-based Vitek MS system. The overall phenotypic misidentification rate was 3.4% (18/533), with considerable variation between hospitals (0.0% to 19.0%), compared to 1.1% (6/533) for the Vitek MS system.


Asunto(s)
Fungemia/diagnóstico , Fungemia/microbiología , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , Levaduras/clasificación , Levaduras/aislamiento & purificación , Errores Diagnósticos/estadística & datos numéricos , Hospitales Universitarios , Humanos , República de Corea , Levaduras/química
7.
J Korean Med Sci ; 28(1): 62-6, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23341713

RESUMEN

The aim of this study was to determine antimicrobial susceptibility of recent clinical Stenotrophomonas maltophilia isolates from Korea, and to compare the activity levels of several combinations of antimicrobials. A total of 206 non-duplicate clinical isolates of S. maltophilia was collected in 2010 from 11 university hospitals. Antimicrobial susceptibility testing was performed using the Clinical Laboratory Standards Institute agar dilution method. In vitro activity of antimicrobial combinations was tested using the checkerboard method. The susceptibility rates to trimethoprim-sulfamethoxazole and minocycline were 96% and 99%, respectively. The susceptibility rate to levofloxacin was 64%. All of four antimicrobial combinations showed synergy against many S. maltophilia isolates. A combination of trimethoprim-sulfamethoxazole plus ticarcillin-clavulanate was most synergistic among the combinations. None of the combinations showed antagonistic activity. Therefore, some of the combinations may be more useful than individual drugs in the treatment of S. maltophilia infection. Further clinical studies are warranted to validate our in vitro test results.


Asunto(s)
Antiinfecciosos/farmacología , Stenotrophomonas maltophilia/efectos de los fármacos , Infecciones por Bacterias Gramnegativas/microbiología , Hospitales Universitarios , Humanos , Levofloxacino , Pruebas de Sensibilidad Microbiana , Minociclina/farmacología , Ofloxacino/farmacología , República de Corea , Stenotrophomonas maltophilia/aislamiento & purificación , Combinación Trimetoprim y Sulfametoxazol/farmacología
8.
J Clin Microbiol ; 50(9): 3129-32, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22760051

RESUMEN

We report a multidrug-resistant strain of Leclercia adecarboxylata responsible for catheter-related bacteremia in a 47-year-old female with breast cancer. The isolated strain was resistant to several ß-lactams, aminoglycosides, and folate pathway inhibitors and harbored bla(TEM-1) and bla(CTX-M) group 1 and intl1 genes (dfrA12-orfF-aadA2) as genetic determinants for resistance. Based on a review of the L. adecarboxylata literature, there have been only 4 reports of antibiotic-resistant strains. To our knowledge, this is the first report of an L. adecarboxylata strain with simultaneous resistance to ß-lactams, aminoglycosides, and sulfonamides.


Asunto(s)
Bacteriemia/diagnóstico , Neoplasias de la Mama/complicaciones , Infecciones Relacionadas con Catéteres/diagnóstico , Infecciones por Enterobacteriaceae/diagnóstico , Enterobacteriaceae/aislamiento & purificación , Antibacterianos/farmacología , Bacteriemia/microbiología , Bacteriemia/patología , Infecciones Relacionadas con Catéteres/microbiología , Infecciones Relacionadas con Catéteres/patología , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Farmacorresistencia Bacteriana Múltiple , Enterobacteriaceae/clasificación , Enterobacteriaceae/genética , Infecciones por Enterobacteriaceae/microbiología , Infecciones por Enterobacteriaceae/patología , Femenino , Genes Bacterianos , Genotipo , Humanos , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Datos de Secuencia Molecular , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , beta-Lactamasas/genética
9.
J Gerontol B Psychol Sci Soc Sci ; 77(4): e64-e69, 2022 04 01.
Artículo en Inglés | MEDLINE | ID: mdl-33881504

RESUMEN

OBJECTIVES: We examined sources of vulnerability and resilience among older adults early in the coronavirus disease 2019 (COVID-19) pandemic. METHODS: We surveyed 235 respondents, 51-95 years old (M = 71.35; SD = 7.39; 74% female), including 2 open-ended questions concerning COVID-19-related difficulties and positive experiences during the past week. Using inductive coding, we found 9 final codes for difficulties and 12 for positives and grouped them into socioecological levels: personal, interpersonal, and societal. RESULTS: Difficulties were reported by 94% of the sample, while 63% described positives. Difficulties and positive responses were made at all socioecological levels and illustrated a dialectic between personal-level constraints and opportunities, interpersonal-level social isolation and integration, and societal-level outrage, sorrow, and social optimism. DISCUSSION: Respondents described sources of vulnerabilities and resilience that supported a socioecological approach to understand resilience during this pandemic. A notable example was resilience derived from witnessing and contributing to the community and social solidarity, highlighting the potential of older adults as resources to their communities during the global pandemic.


Asunto(s)
COVID-19 , Pandemias , Anciano , Anciano de 80 o más Años , COVID-19/epidemiología , Femenino , Humanos , Masculino , SARS-CoV-2 , Encuestas y Cuestionarios
10.
J Microbiol Biotechnol ; 32(6): 730-739, 2022 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-35586930

RESUMEN

Methicillin-resistant Staphylococcus aureus (MRSA) causes severe infections and poses a global healthcare challenge. The utilization of novel molecules which confer synergistical effects to existing MRSA-directed antibiotics is one of the well-accepted strategies in lieu of de novo development of new antibiotics. Thymol is a key component of the essential oil of plants in the Thymus and Origanum genera. Despite the absence of antimicrobial potency, thymol is known to inhibit MRSA biofilm formation. However, the anti-MRSA activity of thymol analogs is not well characterized. Here, we assessed the antimicrobial activity of several thymol derivatives and found that 4-chloro-2-isopropyl-5-methylphenol (chlorothymol) has antimicrobial activity against MRSA and in addition it also prevents biofilm formation. Chlorothymol inhibited staphyloxanthin production, slowed MRSA motility, and altered bacterial cell density and size. This compound also showed a synergistic antimicrobial activity with oxacillin against highly resistant S. aureus clinical isolates and biofilms associated with these isolates. Our results demonstrate that chlorinated thymol derivatives should be considered as a new lead compound in anti-MRSA therapeutics.


Asunto(s)
Antiinfecciosos , Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Antibacterianos/farmacología , Antiinfecciosos/farmacología , Biopelículas , Humanos , Pruebas de Sensibilidad Microbiana , Fenoles , Infecciones Estafilocócicas/microbiología , Timol/farmacología
11.
Antibiotics (Basel) ; 11(8)2022 Jul 29.
Artículo en Inglés | MEDLINE | ID: mdl-36009888

RESUMEN

Bacteria can evade antibiotics by acquiring resistance genes, as well as switching to a non-growing dormant state without accompanying genetic modification. Bacteria in this quiescent state are called persisters, and this non-inheritable ability to withstand multiple antibiotics is referred to as antibiotic tolerance. Although all bacteria are considered to be able to form antibiotic-tolerant persisters, the antibiotic tolerance of extremophilic bacteria is poorly understood. Previously, we identified the psychrotolerant bacterium Pseudomonas sp. B14-6 from the glacier foreland of Midtre Lovénbreen in High Arctic Svalbard. Herein, we investigated the resistance and tolerance of Pseudomonas sp. B14-6 against aminoglycosides at various temperatures. This bacterium was resistant to streptomycin and susceptible to apramycin, gentamicin, kanamycin, and tobramycin. The two putative aminoglycoside phosphotransferase genes aph1 and aph2 were the most likely contributors to streptomycin resistance. Notably, unlike the mesophilic Pseudomonas aeruginosa PA14, this cold-adapted bacterium demonstrated reduced susceptibility to all tested aminoglycosides in a temperature-dependent manner. Pseudomonas sp. B14-6 at a lower temperature formed the persister cells that shows tolerance to the 100-fold minimum inhibitory concentration (MIC) of gentamicin, as well as the partially tolerant cells that withstand 25-fold MIC gentamicin. The temperature-dependent gentamicin tolerance appears to result from reduced metabolic activity. Lastly, the partially tolerant Pseudomonas sp. B14-6 cells could slowly proliferate under the bactericidal concentrations of aminoglycosides. Our results demonstrate that Pseudomonas sp. B14-6 has a characteristic ability to form cells with a range of tolerance, which appears to be inversely proportional to its growth rate.

12.
J Clin Microbiol ; 49(7): 2572-7, 2011 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-21562112

RESUMEN

Multilocus sequence typing (MLST) has been successfully applied to the epidemiology of Candida albicans isolates not only within the hospital setting but also in multiple locations nationwide. We performed MLST to investigate the genetic relatedness among bloodstream infection (BSI) isolates of C. albicans recovered from 10 Korean hospitals over a 12-month period. The 156 isolates yielded 112 unique diploid sequence types (DSTs). While 95 DSTs were each derived from a single isolate, 17 DSTs were shared by 61 isolates (39.1%). Interestingly, 111 (71.1%) isolates clustered within previously known clades, and 29 (18.6%) clustered within a new clade that includes strains of Asian origin previously typed as singletons. This MLST study was complemented by restriction endonuclease analysis of genomic DNA using BssHII (REAG-B) in order to evaluate whether strains with identical DSTs and originating from the same hospital corresponded to nosocomial clusters. Importantly, only those isolates with a strong epidemiological relationship showed ≥95% identical REAG-B types. Our results indicate that REAG-B typing can be complementary to MLST but should be limited to the investigation of isolates of identical DSTs and when interhuman transmission is suspected.


Asunto(s)
Candida albicans/clasificación , Candidiasis/microbiología , Fungemia/microbiología , Variación Genética , Tipificación de Secuencias Multilocus , Técnicas de Tipificación Micológica , Polimorfismo de Longitud del Fragmento de Restricción , Candida albicans/genética , Candida albicans/aislamiento & purificación , Candidiasis/epidemiología , Análisis por Conglomerados , ADN de Hongos/genética , Fungemia/epidemiología , Genotipo , Humanos , Epidemiología Molecular , República de Corea/epidemiología
13.
Int J Biol Macromol ; 190: 722-729, 2021 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-34506862

RESUMEN

Phasin (PhaP), one of the polyhydroxyalkanoate granule-associated protein, enhances cell growth and polyhydroxybutyrate (PHB) biosynthesis by regulating the number and size of PHB granules. However, few studies have applied phasins to various PHB production conditions. In this study, we identified novel phasin genes from the genomic data of Arctic soil bacterium Pseudomonas sp. B14-6 and determined the role of phaP1Ps under different PHB production conditions. Transmission electron microscopy and gel permeation chromatography revealed small PHB granules with high-molecular weight, while differential scanning calorimetry showed that the extracted PHB films had similar thermal properties. The phasin protein derived from Pseudomonas sp. B14-6 revealed higher PHB production and exhibited higher tolerance to several lignocellulosic biosugar-based inhibitors than the phasin protein of Ralstonia eutropha H16 in a recombinant Escherichia coli strain. The increased tolerance to propionate, temperature, and other inhibitors was attributed to the introduction of phaP1Ps, which increased PHB production from lignocellulosic hydrolysate (2.39-fold) in the phaP1Ps strain. However, a combination of phasin proteins isolated from two different sources did not increase PHB production. These findings suggest that phasin could serve as a powerful means to increase robustness and PHB production in heterologous strains.


Asunto(s)
Hidroxibutiratos/metabolismo , Lectinas de Plantas/farmacología , Pseudomonas/química , Rastreo Diferencial de Calorimetría , Carbono/farmacología , Escherichia coli/metabolismo , Hidrólisis , Lignina/metabolismo , Filogenia , Lectinas de Plantas/genética , Temperatura , Factores de Tiempo
14.
Ann Dermatol ; 33(6): 572-576, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34858010

RESUMEN

Nontuberculous mycobacteria are ubiquitous environmental organisms that are rare pathogens in immunocompetent individuals. However, cutaneous nontuberculous mycobacteria infections have been increasingly associated with invasive procedures, including surgery, liposuction, filler injection, intramuscular injection, mesotherapy, piercing, acupuncture, and cupping therapy. Herein, we report the first case of cutaneous nontuberculous mycobacteria infection caused by the East-Asian traditional treatment 'Gua Sha', also known as scraping, coining or spooning in English. A 35-year-old healthy female presented with widespread, painful skin nodules and pustules on her upper and lower extremities that had developed after Gua Sha treatment for body contouring. Histopathologic examination of the lesions revealed granulomatous inflammation in the dermis and the culture isolates were identified as Mycobacterium massiliense with molecular identification. The patient was successfully treated with intermittent incision and drainage of persistent nodules and oral clarithromycin based on antimicrobial susceptibility testing. We recommend implementation of a standard safety protocol for Gua Sha practitioners to minimize the risk of infection transmission.

15.
Sci Total Environ ; 781: 146636, 2021 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-33784526

RESUMEN

The present investigation deals with the adsorptive removal of crude petroleum oil from the water surface using coconut oil-modified pinewood biochar. Biochar generated at higher pyrolysis temperature (700 °C) revealed higher fatty acid-binding efficiency responsible for the excellent hydrophobicity of the biochar. Fatty acids composition attached to the biochar produced at 700 °C was (mg g-1 BC) lauric acid (9.024), myristic acid (5.065), palmitic acid (2.769), capric acid (1.639), oleic acid (1.362), stearic acid (1.114), and linoleic acid (0.130). Simulation of the experimental adsorption data of pristine and modified pinewood biochar generated at 700 °C offered the best fit to pseudo-first-order kinetics (R2 > 0.97) and Langmuir isotherm model (R2 > 0.99) based on the highest regression coefficients. Consequently, the adsorption process was mainly driven by surface hydrophobic interactions including π-π electron-donor-acceptor between electron-rich (π-donor) polycyclic aromatic hydrocarbons from the crude oil and biochar (π-acceptor). A maximum adsorption capacity (Qmax) of 5.315 g g-1 was achieved by modified floating biochar within 60 min. Whereas the reusability testing revealed 49.39% and 51.40% was the adsorption efficiency of pristine and modified biochar at the fifth adsorption-desorption cycle.


Asunto(s)
Petróleo , Pinus , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico , Aceite de Coco , Ácidos Grasos , Cinética , Ácidos Láuricos , Agua , Contaminantes Químicos del Agua/análisis
16.
Int J Biol Macromol ; 167: 151-159, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33249160

RESUMEN

Poly(3-hydroxybutyrate) (PHB) is a common polyhydroxyalkanoate (PHA) with potential as an alternative for petroleum-based plastics. Previously, we reported a new strain, Halomonas sp. YLGW01, which hyperproduces PHB with 94% yield using fructose. In this study, we examined the PHB production machinery of Halomonas sp. YLGW01 in more detail by deep-genome sequencing, which revealed a 3,453,067-bp genome with 65.1% guanine-cytosine content and 3054 genes. We found two acetyl-CoA acetyltransferases (Acetoacetyl-CoA thiolase, PhaA), one acetoacetyl-CoA reductase (PhaB), two PHB synthases (PhaC1, PhaC2), PHB depolymerase (PhaZ), and Enoyl-CoA hydratase (PhaJ) in the genome, along with two fructose kinases and fructose transporter systems, including the phosphotransferase system (PTS) and ATP-binding transport genes. We then examined the PHB production by Halomonas sp. YLGW01 using high-fructose corn syrup (HFCS) containing fructose, glucose, and sucrose in sea water medium, resulting in 7.95 ± 0.11 g/L PHB (content, 67.39 ± 0.34%). PHB was recovered from Halomonas sp. YLGW01 using different detergents; the use of Tween 20 and SDS yielded micro-sized granules with high purity. Overall, these results reveal the distribution of PHB synthetic genes and the sugar utilization system in Halomonas sp. YLGW01 and suggest a possible method for PHB recovery.


Asunto(s)
Medios de Cultivo , Fermentación , Halomonas/metabolismo , Hidroxibutiratos/metabolismo , Poliésteres/metabolismo , Azúcares/química , Azúcares/metabolismo , Biomasa , Vías Biosintéticas/genética , Biología Computacional/métodos , Genoma Bacteriano , Halomonas/genética , Anotación de Secuencia Molecular , Secuenciación Completa del Genoma
17.
J Microbiol Biotechnol ; 31(1): 115-122, 2021 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-33046680

RESUMEN

Phenol-soluble modulins (PSMs) are responsible for regulating biofilm formation, persister cell formation, pmtR expression, host cell lysis, and anti-bacterial effects. To determine the effect of psm deletion on methicillin-resistant Staphylococcus aureus, we investigated psm deletion mutants including Δpsmα, Δpsmß, and Δpsmαß;. These mutants exhibited increased ß-lactam antibiotic resistance to ampicillin and oxacillin that was shown to be caused by increased Nacetylmannosamine kinase (nanK) mRNA expression, which regulates persister cell formation, leading to changes in the pattern of phospholipid fatty acids resulting in increased anteiso-C15:0, and increased membrane hydrophobicity with the deletion of PSMs. When synthetic PSMs were applied to Δpsmα and Δpsmß mutants, treatment of Δpsmα with PSMα1-4 and Δpsmß with PSMß1-2 restored the sensitivity to oxacillin and slightly reduced the biofilm formation. Addition of a single fragment showed that α1, α2, α3, and ß2 had an inhibiting effect on biofilms in Δpsmα; however, ß1 showed an enhancing effect on biofilms in Δpsmß. This study demonstrates a possible reason for the increased antibiotic resistance in psm mutants and the effect of PSMs on biofilm formation.


Asunto(s)
Toxinas Bacterianas/farmacología , Farmacorresistencia Bacteriana/efectos de los fármacos , Farmacorresistencia Bacteriana/genética , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/genética , Antibacterianos/farmacología , Biopelículas/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Genes Bacterianos/genética , Mutación , Infecciones Estafilocócicas
18.
Polymers (Basel) ; 13(7)2021 Mar 29.
Artículo en Inglés | MEDLINE | ID: mdl-33805577

RESUMEN

Polyhydroxyalkanoates (PHAs) are attractive new bioplastics for the replacement of plastics derived from fossil fuels. With their biodegradable properties, they have also recently been applied to the medical field. As poly(3-hydroxybutyrate) produced by wild-type Ralstonia eutropha has limitations with regard to its physical properties, it is advantageous to synthesize co- or terpolymers with medium-chain-length monomers. In this study, tung oil, which has antioxidant activity due to its 80% α-eleostearic acid content, was used as a carbon source and terpolymer P(53 mol% 3-hydroxybytyrate-co-2 mol% 3-hydroxyvalerate-co-45 mol% 3-hydroxyhexanoate) with a high proportion of 3-hydroxyhexanoate was produced in R. eutropha Re2133/pCB81. To avail the benefits of α-eleostearic acid in the tung oil-based medium, we performed partial harvesting of PHA by using a mild water wash to recover PHA and residual tung oil on the PHA film. This resulted in a film coated with residual tung oil, showing antioxidant activity. Here, we report the first application of tung oil as a substrate for PHA production, introducing a high proportion of hydroxyhexanoate monomer into the terpolymer. Additionally, the residual tung oil was used as an antioxidant coating, resulting in the production of bioactive PHA, expanding the applicability to the medical field.

19.
J Microbiol Biotechnol ; 31(8): 1060-1068, 2021 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-34226408

RESUMEN

Community-associated Methicillin-Resistant Staphylococcus aureus (CA-MRSA) is notorious as a leading cause of soft tissue infections. Despite several studies on the Agr regulator, the mechanisms of action of Agr on the virulence factors in different strains are still unknown. To reveal the role of Agr in different CA-MRSA, we investigated the LACΔagr mutant and the MW2Δagr mutant by comparing LAC (USA300), MW2 (USA400), and Δagr mutants. The changes of Δagr mutants in sensitivity to oxacillin and several virulence factors such as biofilm formation, pigmentation, motility, and membrane properties were monitored. LACΔagr and MW2Δagr mutants showed different oxacillin sensitivity and biofilm formation compared to the LAC and MW2 strains. Regardless of the strain, the motility was reduced in Δagr mutants. And there was an increase in the long chain fatty acid in phospholipid fatty acid composition of Δagr mutants. Other properties such as biofilm formation, pigmentation, motility, and membrane properties were different in both Δagr mutants. The Agr regulator may have a common role like the control of motility and straindependent roles such as antibiotic resistance, biofilm formation, change of membrane, and pigment production. It does not seem easy to control all MRSA by targeting the Agr regulator only as it showed strain-dependent behaviors.


Asunto(s)
Proteínas Bacterianas/metabolismo , Staphylococcus aureus Resistente a Meticilina/fisiología , Transactivadores/metabolismo , Proteínas Bacterianas/genética , Biopelículas/crecimiento & desarrollo , Membrana Celular/química , Membrana Celular/metabolismo , Infecciones Comunitarias Adquiridas/microbiología , Farmacorresistencia Bacteriana/genética , Ácidos Grasos/química , Locomoción/genética , Staphylococcus aureus Resistente a Meticilina/genética , Staphylococcus aureus Resistente a Meticilina/metabolismo , Mutación , Fosfolípidos/química , Pigmentación/genética , Infecciones Estafilocócicas/microbiología , Transactivadores/genética
20.
Polymers (Basel) ; 13(9)2021 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-33925903

RESUMEN

Arctic bacteria employ various mechanisms to survive harsh conditions, one of which is to accumulate carbon and energy inside the cell in the form of polyhydroxyalkanoate (PHA). Whole-genome sequencing of a new Arctic soil bacterium Pseudomonas sp. B14-6 revealed two PHA-production-related gene clusters containing four PHA synthase genes (phaC). Pseudomonas sp. B14-6 produced poly(6% 3-hydroxybutyrate-co-94% 3-hydroxyalkanoate) from various carbon sources, containing short-chain-length PHA (scl-PHA) and medium-chain-length PHA (mcl-PHA) composed of various monomers analyzed by GC-MS, such as 3-hydroxybutyrate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, 3-hydroxydodecenoic acid, 3-hydroxydodecanoic acid, and 3-hydroxytetradecanoic acid. By optimizing the PHA production media, we achieved 34.6% PHA content using 5% fructose, and 23.7% PHA content using 5% fructose syrup. Differential scanning calorimetry of the scl-co-mcl PHA determined a glass transition temperature (Tg) of 15.3 °C, melting temperature of 112.8 °C, crystallization temperature of 86.8 °C, and 3.82% crystallinity. In addition, gel permeation chromatography revealed a number average molecular weight of 3.6 × 104, weight average molecular weight of 9.1 × 104, and polydispersity index value of 2.5. Overall, the novel Pseudomonas sp. B14-6 produced a polymer with high medium-chain-length content, low Tg, and low crystallinity, indicating its potential use in medical applications.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA