Development of an LB cloning system and its application in expression of fusion genes in Sphingomonas sp. WG / 生物工程学报

In order to overcome the challenges of insufficient restriction enzyme sites, and construct a fusion-expression vector with flexible fusion direction, we designed an LB cloning system based on the type IIS and type IIT restriction enzymes LguⅠ and BbvCⅠ. The LB cloning system is constructed by inserting the LB fragment (GCTCTTCCTCAGC) into the multiple cloning site region of the broad-host plasmid pBBR1MCS-3 using PCR. The LB fragment contains partially overlapped recognition sites of LguⅠ and BbvCⅠ. Therefore, the same non-palindromic sequence will be generated by these two restriction endonucleases digestion. This feature can be used to quickly and flexibly insert multiple genes into the expression vector in a stepwise and directed way. In order to verify the efficacy of the cloning system, two glycosyltransferase genes welB and welK of Sphingomonas sp. WG were consecutively fused to the LB cloning vector, and the recombinant plasmid was transferred into Sphingomonas sp. WG by triparental mating. The results showed that gene fusion expression has little effect on sphingan titer, but enhanced the viscosity of sphingan. The viscosity of the sphingan produced by recombinant strain Sphingomonas sp. WG/pBBR1MCS-3-LB-welKB was 24.7% higher than that of the wild strain after fermentation for 84 h, which would be beneficial for its application. In conclusion, the application of LB cloning system were verified using Sphingomonas sp. WG. The LB cloning system may provide an efficient tool for fusion expression of target genes.

Enzymatic preparation of manno-oligosaccharides from locust bean gum and palm kernel cake, and investigations into its prebiotic activity

BACKGROUND: Manno-oligosaccharides (MOS) is known as a kind of prebiotics. Mannanase plays a key role for the degradation of mannan to produce MOS. In this study, the mannanases of glycoside hydrolase (GH) families 5 Man5HJ14 and GH26 ManAJB13 were employed to prepare MOS from locust bean gum (LBG) and palm kernel cake (PKC). The prebiotic activity and utilization of MOS were assessed in vitro using the probiotic Lactobacillus plantarum strain. RESULTS: Galactomannan from LBG was converted to MOS ranging in size from mannose up to mannoheptose by Man5HJ14 and ManAJB13. Mannoheptose was got from the hydrolysates produced by Man5HJ14, which mannohexaose was obtained from LBG hydrolyzed by ManAJB13. However, the same components of MOS ranging in size from mannose up to mannotetrose were observed between PKC hydrolyzed by the mannanases mentioned above. MOS stability was not affected by high-temperature and high-pressure condition at their natural pH. Based on in vitro growth study, all MOS from LBG and PKC was effective in promoting the growth of L. plantarum CICC 24202, with the strain preferring to use mannose to mannotriose, rather than above mannotetrose. CONCLUSIONS: The effect of mannanases and mannan difference on MOS composition was studied. All of MOS hydrolysates showed the stability in adversity condition and prebiotic activity of L. plantarum, which would have potential application in the biotechnological applications.

A Case of Chryseobacterium hominis Isolated from Human Blood Drawn Through Peripherally Inserted Central Catheter

Chryseobacterium hominis is non-fermenting Gram-negative rod that was first identified as a novel species in 2007. Here, we report the first clinical case of C. hominis bacteremia, which was confirmed by MALDI-TOF MS and 16S rRNA gene sequencing. A 16-year-old boy diagnosed with acute lymphoblastic leukemia was hospitalized for three months. Two sets of blood culture test through a peripherally inserted central catheter (PICC), which was inserted a month ago, was performed when his white blood cell count declined and he had a high fever. Colonies of medium sizes that looked round, mucoid, sticky, and grayish on blood and chocolate agar plates were observed. Identification of bacteria using the VITEK MALDI-TOF MS system (BioMérieux, France) was not successful and the VITEK 2 system (BioMérieux, USA) indicated Sphingomonas paucimobilis, with a questionable level of confidence (92%). However, Microflex LT Biotyper (Bruker Daltonics, Germany) showed C. homins (log score: 1.81) and sequence of 16S rRNA showed a 100% identity with C. hominis. Piperacillin-tazobactam was administered since the isolate was susceptible to piperacillin-tazobactam but C. hominis showed growth in the next four follow-up culture of blood drawn through PICC. The fever subsided only after PICC was changed. The clinical prognosis and antimicrobial susceptibility test of C. hominis should be further studied.

Rizobacterias promotoras de crecimiento en Guarianthe skinneri (Orchidaceae) / Growth-promoting rhizobacteria from Guarianthe skinneri (Orchidaceae)

Resumen La orquídea Guarianthe skinneri está incluida en la norma NOM-059-ECOL-2010 de México como una especie amenazada. Con el fin de estudiar las BPCV (bacterias promotoras del crecimiento vegetal) en esta orquídea, se recolectaron 10 raíces de diferentes plantas para aislar bacterias asociadas a las raíces, que se analizaron mediante pruebas in vitro como: producción de AIA, fijación de nitrógeno, interacción con el hongo micorrízico Thanatephorus sp. cepa RG26 y solubilización de fosfato. De los 71 aislados bacterianos se caracterizaron 10 cepas mediante secuenciación con el marcador 16s rADN y se identificaron seis cepas: Sphingomonas sp., Sinorhizobium sp., Bacillus sp., Nocardia cerradoensis, Bacillus megaterium y Burkholderia phytofirmans. Se observó que la bacteria Sinorhizobium sp. produjo mayor cantidad de AIA (69.189 µg/ml) y Bacillus sp. presentó mayor reducción de acetileno (10.251 nmol cultivo/96 h). En las interacciones de las bacterias y el hongo RG26 se presentaron cuatro categorías (sumamente positivo, positivo, antagonismo 50-50 e inhibición). En relación a la solubilización de fosfato, la bacteria Burkholderia phytofirmans presentó mayor IS a las 48 y 96 hr con IS de 3.11 y 3.48, respectivamente. Los resultados indican que Bacillus sp. pudiera tener las mejores características para promover el desarrollo de la orquídea G. skinneri mediante la inoculación de semillas y plántulas.

Abstract The Guarianthe skinneri orchid is included in NOM-059-ECOL-2010, Mexico standard as an endangered species. In order to study PGPR (promoting growth plant rhizobacteria) from this orchid, 10 roots were collected from different plants to isolate bacteria associated with the roots, which were analyzed by in vitro tests such as: production of AIA, nitrogen fixation, interaction with the mycorrhizal fungus Thanatephorus sp. strain RG26 and phosphate solubilization. We obtain 71 bacterial isolates, 10 strains of them were characterized by sequencing with the 16d rDNA marker identifying six bacteria: Sphingomonas sp. Sinorhizobium sp. Bacillus sp. Nocardia cerradoensis, Bacillus megaterium and Burkholderia phytofirmans. We observed that the bacterium Sinorhizobium sp. produced a greater amount of AIA (69.189 μg/ml) and Bacillus sp. performed greater acetylene reduction (10.251 nmol cultivo/96h). In the interactions of the bacteria and the fungus RG26, four categories were presented (extremely positive, positive, antagonism 50-50 and inhibition). In relation to the solubilization of phosphate, Burkholderia phytofirmans presented higher IS after 48 and 96 hr with an IS of 3.11 and 3.48, respectively. The results indicate that Bacillus sp. it could have the best characteristics to promote the development of the G. skinneri orchid by inoculating seeds and seedlings. Rev. Biol. Trop. 66(3): 953-968. Epub 2018 September 01.

Adhesion and Biofilm Formation Abilities of Bacteria Isolated from Dental Unit Waterlines / 치위생과학회지

The purpose of our study is to compare the adhesion and biofilm formation abilities of isolates from water discharged from dental unit waterlines (DUWLs). Bacteria were isolated from a total of 15 DUWLs. Twelve isolates were selected for the experiment. To confirm the adhesion ability of the isolates, each isolate was attached to a glass coverslip using a 12-well plate. Plates were incubated at 26℃ for 7 days, and the degree of adhesion of each isolate was scored. To verify the biofilm formation ability of each isolate, biofilms were allowed to form on a 96-well polystyrene flat-bottom microtiter plate. The biofilm accumulations of all isolates formed at 26℃ for 7 days were identified and compared. A total of 56 strains were isolated from 15 water samples including 12 genera and 31 species. Of the 56 isolates, 12 isolates were selected according to the genus and used in the experiment. Sphingomonas echinoides, Methylobacterium aquaticum, and Cupriavidus pauculus had the highest adhesion ability scores of +3 among 12 isolates. Among these three isolates, the biofilm accumulation of C. pauculus was the highest and that of S. echinoides was the third-most abundant. The lowest biofilm accumulations were identified in Microbacterium testaceum and M. aquaticum. Most isolates with high adhesion ability also exhibited high biofilm formation ability. Analysis of adhesion and biofilm formation of the isolates from DUWLs can provide useful information to understand the mechanism of DUWL biofilm formation and development.

Perfil de resistencia antimicrobiana en bacilos Gram negativos no fermentadores aislados en fuentes hídricas / Antimicrobial resistance profile in non-fermenting gram negative bacilli isolated in water resources

La amplia distribución de los bacilos gram negativos no fermentadores en medios ambientales como el agua y especies vegetales cobra importancia al ser reconocidos como agentes causales de enfermedades en pacientes inmunocomprometidos, de allí la relevancia del porque debemos conocer la prevalencia y perfil de susceptibilidad de estos microorganismos en ambientes no hospitalarios. Materiales y Métodos: Estudio transversal, realizado en muestras hídricas de fuentes naturales y artificiales de almacenamiento para el consumo humano en la ciudad de Bogotá y municipios aledaños. La identificación se realizó a través de pruebas IMVIC y el perfil de resistencia a través del método de kirby bauer o E-TEST®. Resultados: Se obtuvieron 42 muestras, 7 (16,6%) con aislamientos de interés: 3 (60%) Pseudomonas spp, 2 (20%) Acinetobacter spp, 1 (10%) Sphingomonas paucimobilis y 1 (10%) Pantoea spp. El 70% presento resistencia a la ceftriaxona, el 30% a cefoxitina, 20% a gentamicina, 10% a ciprofloxacina y 10% a piperacilina-tazobactam. No se presentó resistencia a imipenem. Conclusión: 5 de 7 aislamientos revelaron un BGNNF de importancia en infección en humanos, siendo importante la resistencia encontrada a la ceftriaxona.

The wide distribution of non-fermenting gram negative bacilli in environmental media such as water and plants becomes important as they are recognized a cause of diseases in immunocompromised patients, that’s the reason why we should to know the prevalence and the susceptibility profile of these microorganisms in non-hospital environments. Materials and Methods: Cross-sectional study done with samples of natural and artificial water storage for human consumption in the city of Bogotá and surrounding municipalities. The identification was made through IMVIC tests and the resistance profile through the kirby bauer or E-TEST® method. Results: 42 samples were obtained, 7 (16.6%) with isolates of interest: 3 (60%) Pseudomonas spp, 2 (20%) Acinetobacter spp, 1 (10%) Sphingomonas paucimobilis and 1 (10%) Pantoea spp. The 70% had resistance to ceftriaxone, 30% to cefoxitin, 20% to gentamicin, 10% to ciprofloxacin and 10% to piperacillin-tazobactam. No resistance to imipenem was shown. Conclusion: 5 of 7 isolates revealed a BGNNF of importance in infection in humans, with an important resistance to ceftriaxone.

Biocontrol Activity of Volatile-Producing Bacillus megaterium and Pseudomonas protegens against Aspergillus flavus and Aflatoxin Production on Stored Rice Grains

In our previous study, three bacterial strains, Bacillus megaterium KU143, Microbacterium testaceum KU313, and Pseudomonas protegens AS15, were selected as effective biocontrol agents against Aspergillus flavus on stored rice grains. In this study, we evaluated the inhibitory effects of the volatiles produced by the strains on A. flavus growth and aflatoxin production on stored rice grains. The three strains significantly reduced mycelial growth of A. flavus in dual-culture assays compared with the negative control strain, Sphingomonas aquatilis KU408, and an untreated control. Of these tested strains, volatiles produced by B. megaterium KU143 and P. protegens AS15 markedly inhibited mycelial growth, sporulation, and conidial germination of A. flavus on agar medium and suppressed the fungal populations in rice grains. Moreover, volatiles produced by these two strains significantly reduced aflatoxin production in the rice grains by A. flavus. To our knowledge, this is the first report of the suppression of A. flavus aflatoxin production in rice grains using B. megaterium and P. protegens volatiles.

Sphingomonas Paucimobilis: A Rare Infectious Agent Found in Cerebrospinal Fluid

Sphingomonas paucimobilis (S. paucimobilis) is a gram negative bacillus. It has existed in soil, drinking water and plants. It has been isolated from distilled water tanks, respirators, and hemodialysis devices at the hospital setting. Patients with chronic disorders or immune suppression may be susceptible to infections with it. This microorganism has also been reported to infect healthy persons. Both nosocomial and community-acquired infections have been reported. So far, a variety of infections have been reported, including sepsis, septic pulmonary embolism, septic arthritis, peritonitis, and endophthalmitis. Only 2 cases of meningitis have been reported so far in the literature. So far, no previous reports of culture proliferation have been reported in patients with external ventricular drains, as was the case in our patient. Therefore, our case is the first to have S. paucimobilis proliferation in cerebrospinal fluid culture during intensive care unit stay for an external ventricular drain.

Sphingomonas from petroleum-contaminated soils in Shenfu, China and their PAHs degradation abilities

Abstract Members of the Sphingomonas genus are often isolated from petroleum-contaminated soils due to their unique abilities to degrade polycyclic aromatic hydrocarbons (PAHs), which are important for in situ bioremediation. In this study, a combined phenotypic and genotypic approach using streptomycin-containing medium and Sphingomonas -specific PCR was developed to isolate and identify culturable Sphingomonas strains present in petroleum-contaminated soils in the Shenfu wastewater irrigation zone. Of the 15 soil samples examined, 12 soils yielded yellow streptomycin-resistant colonies. The largest number of yellow colony-forming units (CFUs) could reach 105 CFUs g-1 soil. The number of yellow CFUs had a significant positive correlation (p < 0.05) with the ratio of PAHs to total petroleum hydrocarbons (TPH), indicating that Sphingomonas may play a key role in degrading the PAH fraction of the petroleum contaminants at this site. Sixty yellow colonies were selected randomly and analyzed by colony PCR using Sphingomonas -specific primers, out of which 48 isolates had PCR-positive signals. The 48 positive amplicons generated 8 distinct restriction fragment length polymorphism (RFLP) patterns, and 7 out of 8 phylotypes were identified as Sphingomonas by 16S rRNA gene sequencing of the representative strains. Within these 7 Sphingomonas strains, 6 strains were capable of using fluorene as the sole carbon source, while 2 strains were phenanthrene-degrading Sphingomonas. To the best of our knowledge, this is the first report to evaluate the relationship between PAHs contamination levels and culturable Sphingomonas in environmental samples.

Epizootiological characteristics of viable bacteria and fungi in indoor air from porcine, chicken, or bovine husbandry confinement buildings

Microorganisms found in bioaerosols from animal confinement buildings not only foster the risk of spreading diseases among livestock buildings, but also pose health hazards to farm workers and nearby residents. This study identified the various microorganisms present in the air of swine, chicken, and cattle farms with different kinds of ventilation conditions in Korea. Microbial air samples were collected onto Petri dishes with bacterial or fungal growth media using a cascade impactor. Endotoxin levels in total dust were determined by the limulus amebocyte lysate kinetic QCL method. Prevalent Gram-positive bacteria were Staphylococcus (S.) lentus, S. chromogenes, Bacillus (B.) cereus, B. licheniformis, and Enterococcus faecalis, while the dominant fungi and Gram-negative bacteria were Candida albicans and Sphingomonas paucimobilis, respectively. Considering no significant relationship between the indoor dust endotoxin levels and the isolation of Gram-negative bacteria from the indoor air, monitoring the indoor airborne endotoxin level was found to be also critical for risk assessment on health for animals or workers. The present study confirms the importance of microbiological monitoring and control on animal husbandry indoor air to ensure animal and worker welfare.

Endoftalmitis poscirugía de catarata por Sphingomonas paucimobilis / Sphingomonas paucimobilis-induced endophthalmitis after cataract surgery

Se presenta la caracterización y manejo terapéutico de un caso de endoftalmitis bacteriana posoperatoria causada por el germen Sphingomonas paucimobilis. La endoftalmitis es la inflamación de los tejidos intraoculares, considerada como la más devastadora de las complicaciones posoperatorias; posee pronóstico visual muy reservado y un elevado riesgo de secuela. Las Sphingomonas paucimobilis son bacterias gramnegativas con forma de bacilo, quimioheterótrofa y estrictamente aerobias que causan enfermedades en los seres humanos, principalmente infecciones hospitalarias que típicamente son tratadas fácilmente con antibióticos. Por sus capacidades biodegradantes y biosintéticas, son pocos los reportes hallados de infección intraocular por este germen. El pronóstico visual es favorable con un diagnóstico precoz y la aplicación del tratamiento adecuado. En este artículo se presentan un caso de endoftalmitis poscirugía de catarata por Sphingomonas paucimobilis reportado en Cuba en el mes de septiembre de 2009.

The characterization and therapeutic management of a case of postsurgery bacterial endophthalmitis caused by Shingomonas paucimobilis was presented. Endophthalmitis is the inflammation of the intraocular tissues and considered as the most devastating postoperative complication. The visual prognosis of this disease is very reserved judgement and high risk of sequelae. Sphingomonas paucimobilis are bacillus-shaped, chemoheterotrophic and strictly aerobic Gramnegative bacteria that cause diseases in the human being, mainly nosocomial infections that are typically treated with antibiotics. Based on its biodegrading and biosynthetic capacities, there are few reports on intraocular infections caused by this germ. The visual prognosis is favourable when the disease is early diagnosed and adequately managed. A case of endophthalmitis following a cataract surgery and caused by Shingomonas paucimobilis in Cuba in September 2009 was presented in this article.

Intestinal Microbial Community Profiles of a Newborn Preterm Infant Using Pyrosequencing Analysis: Pilot Study

DNA pyrosequencing, one of the advanced methods for DNA sequencing, has been employed for phylogenetic analysis of bacterial communities using the conserved 16S rRNA gene. We performed a pilot study on a mother-neonate pair utilizing the DNA pyrosequencing assays to investigate the diversity of microbial communities in maternal amniotic fluid (AF), vagina, and rectum and newborn gastric fluid (GF) and stool. Phylum level analysis revealed that bacterial community was dominated by Firmicutes (63.2%) in maternal feces, and Actinobacteria (84.9%) in maternal vaginal swab. The bacterial communities in both the AF and GF were dominated by Proteobacteria (67.8%). Interestingly, the bacterial community in the newborn's meconium was quite similar to that in the AF. However, the composition of the bacterial community in newborn's feces was different on day 14 and dominated by Firmicutes (91.1%). Genus-level analysis revealed that the bacterial community in maternal feces was dominated by Anaerococcus (19.5%) and Prevotella (18.7%), whereas that in the maternal vaginal swab was dominated by Atopobium (83.6%). The bacterial communities in both the AF and GF were dominated by Sphingomonas (38.5%). The bacterial community in the newborn's meconium was quite similar to that in the AF, which was dominated by Sphingomonas (45.2%). However, the composition of bacterial community in the newborn's feces on day 14 was relatively different. Future studies with a large number of infants are needed to determine the factors involved in the changing profile of newborn's fecal bacterial communities.

Characteristic of bacterial flora from the uterus in HanWoo cattle / 대한수의학회지

Uterine sterilization is important for improving fertility in cattle. This study compared bacterial flora in the uterus between healthy and repeat breeder cows (RBCs). The uterine flushing of six heifers, 13 healthy HanWoo cows and eight RBCs (HanWoo) were sampled, and 15 frozen semen samples were selected. Overall, 35 bacteria were identified from in HanWoo uterine flushing and semen. The bacterial genera identified from HanWoo uterine flushing were Alloiococcus, Bacillus, Enterobacter, Enterococcus, Erysipelothrix, Gardnerella, Granulicatella, Kocuria, Pantoea, Pasteurella, Rothia, Serratia, Sphingomonas, Staphylococcus, Stenotrophomonas and Streptococcus. The bacterial genera identified from HanWoo semen were Bacillus, Escherichia, Kocuria, Oligella, Pseudomonas, Serratia, Sphingomonas, Staphylococcus, Stenotrophomonas and Streptococcus. The prevalence and presence of the identified bacteria between healthy cows and RBCs differed significantly. Further studies are needed to determine the role of these bacteria in the uterus of HanWoo cattle with reproductive disorder.

A case of peritoneal dialysis-associated peritonitis caused by Sphingomonas paucimobilis

Sphingomonas paucimobilis is an aerobic Gram-negative bacillus found in soil and water. Knowledge regarding the role of this infectious agent is limited because it is rarely isolated from human material. Furthermore, it is an unusual pathogen in cases of peritoneal dialysis (PD)-associated peritonitis. The clinical courses and outcomes of peritonitis caused by S. paucimobilis are variable. Whereas some patients were cured with appropriate antibiotic therapy, others required catheter removal. Cases of PD-associated peritonitis caused by S. paucimobilis have been reported worldwide, and there was a case report of coinfection with S. paucimobilis and Chryseobacterium indologenes in Korea. However, there has been no case caused by S. paucimobilis as a single pathogen. We report a case of PD-associated peritonitis due to S. paucimobilis in which the patient recovered after catheter removal.

Hydrocarbon degrading microflora in a tropical fuel-contaminated aquifer: assessing the feasibility of PAH bioremediation

An aquifer located within a petroleum processing plant in Moin, Costa Rica, suffers hydrocarbon pollution. This study aimed to determine the ability of indigenous microorganisms from this site to degrade polycyclic aromatic hydrocarbons [PAHs] to evaluate the feasibility of an eventual bioremediation process. Aerobic conditions were found in the aquifer, while microbial analyses of the groundwater indicated the presence of important hydrocarbon-degrading populations. Sixteen PAH-degrading strains were isolated with the ability to grow on naphthalene [5 strains], phenanthrene [3], fluorene [6] and pyrene [2]. Most of the identified isolates belonged to the genus Pseudomonas, although, Comamonas, Sphingomonas Stenotrophomonas and Delftia were also found. A mixture of selected strains was evaluated by its performance of PAH degradation in soil-slurry systems, where efficiency of removal was naphthalene > fluorene > phenanthrene > pyrene. This study is an initial approach to evaluate the feasibility of applying a bioremediation process in the contaminated site

Monitoring of antibiotic resistance in bacteria isolated from laboratory animals / 한국실험동물학회지

The drug resistance of microorganisms isolated from laboratory animals never treated with antibiotics is being reported consistently, while the number of laboratory animals used in medicine, pharmacy, veterinary medicine, agriculture, nutrition, and environmental and health science has increased rapidly in Korea. Therefore, this study examined the development of antimicrobial resistance in bacteria isolated from laboratory animals bred in Korea. A total of 443 isolates (7 species) containing 5 Sphingomonas paucimobilis, 206 Escherichia coli, 60 Staphylococcus aureus, 15 Staphylococcus epidermidis, 77 Enterococcus faecalis, 27 Citrobacter freundii, 35 Acinetobacter baumannii were collected from the nose, intestine, bronchus and reproductive organs of ICR mice and SD rats. Of these species, Acinetobacter baumannii and Enterococcus faecalis showed significant antimicrobial resistance according to the minimum inhibition concentration (MIC) in E-test. In case of Acinetobacter baumannii, several isolates showed MIC values 16-128 microg/mL for cefazolin and cefoxitin, and higher resistance (128-512 microg/mL) to nitrofurantoin than that of standard type. Resistance to cefazolin, cefoxitin and nitrofurantoin was detected in 17.14, 20.00, and 8.57% of the Acinetobacter baumannii isolates, respectively. In addition, 44.1% of the Enterococcus faecalis isolates collected from the laboratory animals were resistant to oxacillin concentration of 16-32 microg/mL range, while MIC value of standard type was below oxacillin concentration of 6 microg/mL. These results suggest that in rodent species of laboratory animals, Acinetobacter baumannii are resistance to cefazolin, cefoxitin and nitrofurantoin, whereas those of Enterococcus faecalis were resistance to oxacillin.

A survey of the bacterial diversity in the cup filler of dental chair units

Water from the cup filler of dental chair units (CFDC) was observed to contain sphingomonads, environmental mycobacteria and methylobacteria, among other minor bacteria. Some of the bacteria detected are recognized opportunistic pathogens. Some of these, tended to persist over time.

Efecto de la inoculación de la cepa Sphingomonas paucimobilis 20006FA sobre la composición de un consorcio bacteriano degradador de fenantreno / Effect of the inoculant strain Sphingomonas paucimobilis 20006FA on the bacterial composition of a phenanthrene-degrading consortium

Se estudió el efecto de la inoculación con la cepa Sphingomonas paucimobilis 20006FA sobre la composición bacteriana de un consorcio degradador de fenantreno en cultivos discontinuos (batch) con 8 repiques sucesivos. El consorcio original se obtuvo a partir de un suelo prístino. A los fines del estudio, se obtuvieron y mantuvieron dos consorcios: uno inoculado (F200+I) y otro sin inocular (F200). Se estudió la diversidad bacteriana de los consorcios mediante el análisis de microorganismos cultivables (por caracterización fenotípica y genotípica) y totales (por PCR-DGGE). A lo largo de los repiques sucesivos pudo observarse en ambos consorcios una tendencia a la pérdida de la capacidad degradadora de fenantreno, acompañada por una disminución de la diversidad bacteriana. Si bien la inoculación no produjo cambios significativos en la capacidad degradadora de fenantreno de los consorcios (29,9% para F200 y 27,6% para F200+I hacia el tercer repique), sí produjo cambios en la composición bacteriana, ya que los perfiles de DGGE revelaron una dinámica estructural diferente en el consorcio inoculado. En ambos consorcios se pudo observar la presencia de una banda intensa posicionada a la misma altura que el ADN del inóculo en el gel de DGGE; sin embargo, los cultivos aislados de los consorcios que presentaban idéntica posición de banda en el perfil PCR-DGGE que la cepa S. paucimobilis 20006FA mostraron baja similitud con la cepa inoculada mediante la técnica de RAPD.

The effect of the inoculant strain Sphingomonas paucimobilis 20006FA on the bacterial composition of a phenanthrene-degrading consortium obtained from a pristine soil in sequencing batch cultures was studied. Inoculated (F200+I) and non-inoculated (F200) phenanthrene-degrading consortia, were obtained. Bacterial diversity of consortia was studied at cultivable (phenotype and genotype characterization) and non-cultivable (PCR-DGGE) levels. During the successive cultures, a loss in the phenanthrene-degrading capacity and a decrease in the bacterial diversity were observed in both consortia. Although inoculation did not produce any significant changes in the consortia phenanthrene-degrading capacity (29.9% F200 and 27.6% F200+I), it did produce changes in the bacterial composition, showing a differential structural dynamics in the DGGE profiles of the inoculated consortium. In both consortia, a dominant band placed at the same position as that of the DNA of the inoculant strain in the DGGE gel could be observed. However, isolated cultures from the consortia which had an identical band position to that of S. paucimobilis 20006FA in the PCR-DGGE profile showed low similarity with respect to the inoculant strain (RAPD).

A Case of Postoperative Sphingomonas paucimobilis Endophthalmitis After Cataract Extraction

PURPOSE: To report a case of an acute onset of delayed postoperative endophthalmitis that was caused by Sphingomonas paucimobilis. METHODS: This case demonstrates an acute onset of delayed postoperative endophthalmitis at 3 months after uneventful cataract extraction and posterior chamber intraocular lens implantation. We performed vitrectomy, intraocular lens and capsular bag removal, and intravitreal antibiotics injection. On the smear stains from the aspirated vitreous humor, gram-negative bacilli were detected and S. paucimobilis was found in culture. RESULTS: At three months after vitrectomy, the best corrected visual acuity was 20/300. Fundus examination showed mild pale color of optic disc and macular degeneration. CONCLUSIONS: Vitrectomy with intravitreal ceftazidime injection had contributed to the favorable result in case of an acute onset of delayed postoperatire endophthalmitis caused by S. paucimobilis.

A Case of Postoperative Sphingomonas paucimobilis Endophthalmitis After Cataract Extraction

PURPOSE: To report a case of an acute onset of delayed postoperative endophthalmitis that was caused by Sphingomonas paucimobilis. METHODS: This case demonstrates an acute onset of delayed postoperative endophthalmitis at 3 months after uneventful cataract extraction and posterior chamber intraocular lens implantation. We performed vitrectomy, intraocular lens and capsular bag removal, and intravitreal antibiotics injection. On the smear stains from the aspirated vitreous humor, gram-negative bacilli were detected and S. paucimobilis was found in culture. RESULTS: At three months after vitrectomy, the best corrected visual acuity was 20/300. Fundus examination showed mild pale color of optic disc and macular degeneration. CONCLUSIONS: Vitrectomy with intravitreal ceftazidime injection had contributed to the favorable result in case of an acute onset of delayed postoperatire endophthalmitis caused by S. paucimobilis.