Use of modified Richards model to predict isothermal and non-isothermal microbial growth

Abstract Mathematical models are often used to predict microbial growth in food products. An important class of these models involves the adaptation of classical sigmoid functions, such as the Gompertz and logistic functions. This study aimed to validate the use of the modified Richards model in various situations, which have not previously been tested. The model was obtained through solving a system of two differential equations and could be applied to both isothermal and non-isothermal environments. To test and validate this model, we used published datasets containing data for the growth of Pseudomonas spp. in fish products. The results obtained after fitting the model showed that it could be effectively used to describe and predict the Pseudomonas growth curves under various temperature regimens. However, the influence of the shape parameter on the growth curve is an issue that needs further evaluation.

Alginate overproduction and biofilm formation by psychrotolerant Pseudomonas mandelii depend on temperature in Antarctic marine sediments

Background: In recent years, Antarctica has become a key source of biotechnological resources. Native microorganisms have developed a wide range of survival strategies to adapt to the harsh Antarctic environment, including the formation of biofilms. Alginate is the principal component of the exopolysaccharide matrix in biofilms produced by Pseudomonas, and this component is highly demanded for the production of a wide variety of commercial products. There is a constant search for efficient alginate-producing organisms. Results: In this study, a novel strain of Pseudomonas mandelii isolated from Antarctica was characterized and found to overproduce alginate compared with other good alginate producers such as Pseudomonas aeruginosa and Pseudomonas fluorescens. Alginate production and expression levels of the alginate operon were highest at 4°C. It is probable that this alginate-overproducing phenotype was the result of downregulated MucA, an anti-sigma factor of AlgU. Conclusion: Because biofilm formation is an efficient bacterial strategy to overcome stressful conditions, alginate overproduction might represent the best solution for the successful adaptation of P. mandelii to the extreme temperatures of the Antarctic. Through additional research, it is possible that this novel P. mandelii strain could become an additional source for biotechnological alginate production.

Enriquecimiento diferencial de Pseudomonas spp. en el rizoplano de distintas especies cultivadas / Selective enrichment of Pseudomonas spp. in the rhizoplane of different plant species

En contraste con la simbiosis entre rizobios y leguminosas, la especificidad de las Pseudomonas en la colonización radicular parece menos estricta. Sin embargo, estudios sobre la diversidad bacteriana del nicho rizosférico resaltan la influencia de la especie vegetal en la selección específica de ciertos microorganismos a partir de la flora residente del suelo. Para evaluar el efecto que los cultivos extensivos de nuestro país tienen sobre la estructura de las comunidades de Pseudomonas, se realizaron experimentos con plantas trampa, partiendo de semillas de trigo, maíz y soja desinfectadas superficialmente y sembradas en un mismo suelo prístino. A partir de las suspensiones representativas de la microflora del rizoplano, se realizaron recuentos en placa en medio selectivo para Pseudomonas. El conjunto de colonias originado a partir de los distintos rizoplanos se utilizó como fuente de ADN para analizar la estructura de comunidad a través del perfil de restricción de amplicones de los genes oprF y gacA. El análisis comparativo de estos perfiles agrupó a las muestras por especie de planta y las distinguió del patrón obtenido a partir del suelo prístino. La secuenciación parcial del gen 16S ADNr de aislamientos bacterianos representativos confirmó la existencia de genotipos enriquecidos diferencialmente en el rizoplano de cada especie vegetal. Estos resultados apoyan la hipótesis de la existencia de mecanismos de selección específica de estirpes de Pseudomonas a partir de la flora nativa del suelo en la interacción cooperativa entre estas PGPR y las raíces de diferentes cultivos como trigo, soja y maíz

In contrast to rhizobia-legume symbiosis, the specificity for root colonization by pseudomonads seems to be less strict. However, several studies about bacterial diversity in the rhizosphere highlight the influence of plant species on the selective enrichment of certain microorganisms from the bulk soil community. In order to evaluate the effect that different crops have on the structure of pseudomonad community on the root surface, we performed plant trap experiments, using surface-disinfected maize, wheat or soybean seeds that were sown in pots containing the same pristine soil as substrate. Rhizoplane suspensions were plated on a selective medium for Pseudomonas, and pooled colonies served as DNA source to carry out PCR-RFLP community structure analysis of the pseudomonads-specific marker genes oprF and gacA. PCR-RFLP profiles were grouped by plant species, and were distinguished from those of bulk soil samples. Partial sequencing of 16S rDNA genes of some representative colonies of Pseudomonas confirmed the selective enrichment of distinctive genotypes in the rhizoplane of each plant species. These results support the idea that the root systems of agricultural crops such as soybean, maize and wheat, select differential sets of pseudomonads from the native microbial repertoire inhabiting the bulk soil

Bacteria in combination with fertilizers promote root and shoot growth of maize in saline-sodic soil

Salinity is the leading abiotic stress hampering maize (Zea mays L.) growth throughout the world, especially in Pakistan. During salinity stress, the endogenous ethylene level in plants increases, which retards proper root growth and consequent shoot growth of the plants. However, certain bacteria contain the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which converts 1-aminocyclopropane-1-carboxylic acid (an immediate precursor of ethylene biosynthesis in higher plants) into ammonia and α-ketobutyrate instead of ethylene. In the present study, two Pseudomonas bacterial strains containing ACC-deaminase were tested separately and in combinations with mineral fertilizers to determine their potential to minimize/undo the effects of salinity on maize plants grown under saline-sodic field conditions. The data recorded at 30, 50 and 70 days after sowing revealed that both the Pseudomonas bacterial strains improved root and shoot length, root and shoot fresh weight, and root and shoot dry weight up to 34, 43, 35, 71, 55 and 68%, respectively, when applied without chemical fertilizers: these parameter were enhanced up to 108, 95, 100, 131, 100 and 198%, respectively, when the strains were applied along with chemical fertilizers. It can be concluded that ACC-deaminase Pseudomonas bacterial strains applied alone and in conjunction with mineral fertilizers improved the root and shoot growth of maize seedlings grown in saline-sodic soil.

Percepção dos receptores sanguíneos quanto ao processo transfusional / Blood transfusion receivers' perception of the transfusion process / Percepción de transfusión de sangre en el caso de los receptores

Pesquisa qualitativa, exploratória descritiva, que objetivou conhecer a percepção dos receptores sanguíneos quanto ao processo transfusional. A pesquisa foi realizada em uma unidade de hemoterapia de um município da região sul do Brasil e os dados foram analisados por meio do Discurso do Sujeito Coletivo. Foram entrevistados, por meio de instrumento semiestruturado, onze pacientes, homens e mulheres entre 30 e 95 anos, em recuperação pós-cirúrgica de cirurgia cardíaca, submetidos à transfusão sanguínea. Emergiram quatro Ideias Centrais: Perda e reposição sanguínea; Preservação da vida; Reconhecimento do processo transfusional e Segurança transfusional. A percepção sobre a mudança que os pós-transfundidos começam a vivenciar a partir do processo transfusional traz à tona uma ressignificação da própria vida. Este estudo mostrou que os pacientes transfundidos percebem o processo transfusional como uma alternativa de sobrevivência e, mesmo tendo conhecimento sobre o processo e seus significados, permanecem receios e angústias que podem ser minimizados pela equipe multiprofissional.

Qualitative research, descriptive exploratory, aimed to know the perception of blood transfusion recipients as to the process. The research was carried out at a blood bank in a city in southern Brazil, and the data were analyzed using the Collective Subject Discourse. Were interviewed using a semistructured instrument, eleven patients, men and women between 30 and 95 years, post-surgical recovery of cardiac surgery, underwent blood transfusion. Four central ideas emerged: loss and blood replacement; Preservation of life; Recognition of the transfusion process; and transfusion safety. The perception about the change that post-transfusion begin to live from the transfusion process raises a reframing of life itself. This study showed that transfused patients perceive the transfusion process as a means of survival, and even having knowledge about the process and their meanings, there is the permanence of fears and anxieties that can be minimized by the multidisciplinary team.

Investigación cualitativa, de tipo exploratorio descriptivo, con el objetivo de conocer la percepción de los receptores de transfusiones de sangre en cuanto al proceso. La investigación se llevó a cabo en un banco de sangre en una ciudad en el sur de Brasil, y los datos fueron analizados utilizando el Discurso del Sujeto Colectivo. Fueron entrevistados mediante un instrumento semi-estructurado, once pacientes, hombres y mujeres de entre 30 y 95 años de recuperación post-quirúrgica de la cirugía cardíaca, se sometió a una transfusión de sangre. Cuatro ideas centrales surgieron: la pérdida y reemplazo de sangre; La preservación de la vida; Reconocimiento del proceso de transfusión; y seguridad de las transfusiones. La percepción sobre el cambio que después de la transfusión comenzar a vivir desde el proceso de transfusión plantea una reformulación de la vida misma. Este estudio mostró que los pacientes transfundidos perciben el proceso de transfusión como un medio de supervivencia, e incluso tener conocimiento sobre el proceso y sus significados, no es la permanencia de los temores y ansiedades que pueden minimizarse por el equipo multidisciplinario.

Necessidades e preocupações dos pais em diferentes etapas do ciclo vital / Parents' needs and concerns at different stages of the life cycle / Necesidades y preocupaciones de los padres en diferentes etapas del ciclo vital

Objetivo: identificar as necessidades e as preocupações prioritárias, manifestadas pelos pais no desempenho do seu papel, em três etapas do ciclo vital: adolescência, idade produtiva e idade madura. Metodologia: estudo exploratório com abordagem qualitativa, desenvolvido com quatorze pais residentes em um município no extremo sul do Brasil. Os dados foram coletados entre maio e agosto de 2011, por meio de entrevista em profundidade. Através da técnica da análise textual discursiva e da matriz construída com base na teoria bioecológica de Bronfenbrenner, foram construídas três categorias: Necessidades/preocupações do pai, geradas em sua relação com o mundo do trabalho; Necessidades/preocupações que emergem da relação de cuidado com os filhos e Preocupações dos pais com relação ao futuro dos filhos. Conclusão: identificou-se que a preocupação com o futuro dos filhos foi apontada por pais de todas as faixas-etárias investigadas. .

Objective: this study aimed to identify priority needs and concerns expressed by fathers in the performance of their role in three stages of the life cycle: adolescence, productive age, and mature age. Methodology: this is an exploratory study with a qualitative approach, conducted with fourteen fathers residing in a municipality in the extreme south of Brazil. The data were collected between May and August 2011 by means of the in-depth interview. Through the technique of written discourse analysis and the array built upon Bronfenbrenner's bioecological theory, we obtained three categories: fathers' needs/concerns, generated in their relationship with the world of work; needs/concerns that emerged from the relationship of care with the children; and fathers' concerns about the future of the children. Conclusions: we identified that the concern with the future of the children was pointed out by fathers of all age groups investigated. .

Objetivo: identificar las necesidades y preocupaciones prioritarias, manifestadas por los padres en el desempeño de su función, en tres etapas del ciclo de vida: adolescencia, edad productiva y edad madura. Metodología: estudio exploratorio con abordaje cualitativo, desarrollado con catorce padres residentes en un municipio en el extremo sur de Brasil. Los datos fueran colectados entre mayo y agosto de 2011, a través de entrevistas en profundidad. A través de la técnica de análisis textual y discursiva e de la matriz construida basada en la teoria bioecologica de Bronfenbrenner, fueran construidas tres categorías: Necesidades/ preocupaciones de lo padre, generado en suya relación con el mundo de lo trabajo; Necesidades/preocupaciones que emergen de la relación de cuidado con hijos e preocupaciones de los padres con lo futuro de los hijos. Conclusión: Se identifico que la preocupación con el futuro de los hijos fue apuntado por los padres de todas las edades averiguadas. .

Effectiveness of halo-tolerant, auxin producing Pseudomonas and Rhizobium strains to improve osmotic stress tolerance in mung bean (Vigna radiata L.)

Halo-tolerant, auxin producing bacteria could be used to induce salt tolerance in plants. A number of Rhizobium and auxin producing rhizobacterial strains were assessed for their ability to tolerate salt stress by conducting osmoadaptation assay. The selected strains were further screened for their ability to induce osmotic stress tolerance in mung bean seedlings under salt-stressed axenic conditions in growth pouch/jar trials. Three most effective strains of Rhizobium and Pseudomonas containing ACC-deaminase were evaluated in combination, for their ability to induce osmotic stress tolerance in mung bean at original, 4, and 6 dS m-1 under axenic conditions. Results showed that sole inoculation of Rhizobium and Pseudomonas strains improved the total dry matter up to 1.4, and 1.9 fold, respectively, while the increase in salt tolerance index was improved up to 1.3 and 2.0 fold by the Rhizobium and Pseudomonas strains, respectively. However, up to 2.2 fold increase in total dry matter and salt tolerance index was observed due to combined inoculation of Rhizobium and Pseudomonas strains. So, combined application of Rhizobium and Pseudomonas strains could be explored as an effective strategy to induce osmotic stress tolerance in mung bean.

Isolation, molecular characterization and growth-promotion activities of a cold tolerant bacterium Pseudomonas sp. NARs9 (MTCC9002) from the Indian Himalayas

A bacterium that grows and expresses plant growth promotion traits at 4°C was isolated from the rhizospheric soil of Amaranth, cultivated at a high altitude location in the North Western Indian Himalayas. The isolate was Gram negative and the cells appeared as rods (2.91 x 0.71 μm in size). It grew at temperatures ranging from 4 to 30°C, with a growth optimum at 28°C. It exhibited tolerance to a wide pH range (5-10; optimum 8.0) and salt concentrations up to 6 percent (wt/vol). Although it was sensitive to Rifampicin (R 20 μg mi-1), Gentamicin (G 3 μg mi-1), and Streptomycin (S 5 μg mi-1), it showed resistance to higher concentrations of Ampicillin (A 500 μg mi-1), Penicillin (P 300 μg mi-1), Polymixin B sulphate (Pb 100 μg mi-1) and Chloramphenicol (C 200 μg mi-1). The 16S rRNA sequence analysis revealed maximum identity with Pseudomonas lurida. The bacterium produced indole Acetic Acid (IAA) and solubilizes phosphate at 4, 15 and 28°C. It also retained its ability to produce rhamnolipids and siderophores at 15°C. Seed bacterization with the isolate enhanced the germination, shoot and root lengths of thirty-day-old wheat seedlings by 19.2, 30.0 & 22.9 percent respectively, as compared to the un-inoculated controls.

Contact lens-associated microbial keratitis / Ceratites microbianas relacionadas a lente de contato

PURPOSE: Contact lens-associated microbial keratitis is a severe condition with sight-threatening potential and increasing incidence. Information regarding the etiological agents is essential in guiding management and may vary geographically. The aim of this study was to analyze the microbiological results of corneal scrapings collected from patients presenting with contact lens-associated microbial keratitis. METHODS: Retrospective analysis of the records of all patients who were clinically diagnosed with contact lens-associated microbial keratitis and had corneal scrapings sent to the Laboratory of Ocular Microbiology, UNIFESP/EPM during a 5-year period from January 2002 to December 2007. RESULTS: The etiological agent was identified in 239 patients. Bacterial isolates accounted for 166 (69.46 percent) cases, Acanthamoeba for 95 (39.75 percent) cases and fungi for 4 (1.67 percent) cases. Among the bacterial infections, coagulase-negative Staphylococcus was demonstrated in 74 cases, while Pseudomonas spp was found in 32 patients. All coagulase negative Staphylococcus and Pseudomonas were susceptible to ciprofloxacin and ofloxacin. Resistance to gentamicin was documented in a single case of Pseudomonas. Fourth-generation flouoroquinolone resistance was not observed among Pseudomonas cases. CONCLUSION: Coagulase-negative Staphylococcus was the most frequent isolate, and such data must be considered when determining empiric treatment. Second-generation fluoroquinolones ciprofloxacin and ofloxacin and fourth-generation fluoroquinolones moxifloxacin and gatifloxacin showed a good antibacterial profile and therefore could be good options for initial management.

OBJETIVO: A ceratite microbiana associada ao uso de lente de contato é uma condição clínica grave, com risco de perda visual e cuja incidência vem aumentando progressivamente. Os principais agentes etiológicos podem variar geograficamente e informações referentes aos agentes causais são essenciais para tratamento apropriado. Este estudo se propõe a analisar os resultados microbiológicos de raspados de córnea coletados de pacientes usuários de lente de contato com quadro de ceratite microbiana. MÉTODOS: Foi realizada análise retrospectiva de todos os estudos microbiológicos de pacientes usuários de lente de contato com diagnóstico clínico de ceratite microbiana que tiveram material corneal enviado para o Laboratório de Microbiologia Ocular UNIFESP durante o período de 5 anos de janeiro de 2002 a dezembro de 2007. RESULTADOS: Dos 239 pacientes em que foi possível identificação, o agente era bactéria em 166 (69,46 por cento), Acanthamoeba em 95 (39,75 por cento) e fungo em 4 (1,67 por cento). Staphylococcus coagulase negativo foi encontrado em 74 casos, dos quais todos eram sensíveis tanto a ciprofloxacino quanto a ofloxacino. Dois casos de resistência a quinolonas de quarta geração (gatifloxacino e moxifloxacino) foram identificados entre os casos de Staphylococcus coagulase negativo. Pseudomonas spp foi isolada em 32 pacientes, dos quais todos eram sensíveis a quinolonas de segunda geração (ciprofloxacino e ofloxacino) e de quarta geração. Foi encontrado um único caso de Pseudomonas resistente a gentamicina. CONCLUSÃO: Staphylococcus coagulase negativo foi isolado em um número de casos superior a Pseudomonas, o agente tradicionalmente considerado o principal de ceratites microbianas associadas ao uso de lente de contato. Aminoglicosídeos, fluorquinolonas de segunda e de quarta geração apresentaram um perfil antibiótico satisfatório para o tratamento empírico de ceratites microbianas em usuários de lente de contato.

Enhanced crude oil biodegradation and rhamnolipid production by Pseudomonas stutzeri strain G11 in the presence of Tween-80 and Triton X-100.

In this study, the growth of sixty-one bacterial strains in crude oil were determined spectrophotometrically at 620 nm. Pseudomonas aeruginosa G1, Pseudomonas fluorescens G6, Pseudomonas stutzeri G11 and Pseudomonas putida G15 were chosen for the study based on the efficiency of crude oil utilisation. At 1% (v/v) crude oil concentration, P. stutzeri G11 strain degraded a maximum of 69%. The percentage of degradation by the P. stutzeri G11 strain decreased from 69% to 59% as the concentration of crude oil was increased from 1% (v/v) to 2.5% (v/v). Strain G11 was selected to determine the effects of surfactants (Tween-80 and TritonX-100) on the biodegradation of crude oil. While strain G11 showed 76% degradation at mineral salts medium (MSM) containing 1% (v/v) crude oil + 1% (v/v) TritonX-100, it showed 61% degradation at MSM containing 2.5% (v/v) crude oil + 2.5% (v/v) TritonX-100. Also, degradation rate of this strain was 96% in the presence of 1% (v/v) crude oil + 1% (v/v) Tween-80, while degradation rate was 48% in the presence of 25% (v/v) crude oil+ 2.5% (v/v) Tween-80. Additionally, we investigated the rhamnolipid production of P. stutzeri G11 strain both in crude oil and in crude oil + two different surfactants (TritonX-100 and Tween-80, separately). These results suggest that surfactants have improved both crude oil degradation and rhamnolipid production and the degradation rates have depended very much on the chemical structure of surfactants.

Metabolic characteristics of an aerobe isolated from a methylotrophic methanogenic enrichment culture.

An anaerobic methylotrophic methanogenic enrichment culture, with sustained metabolic characteristics, including that of methanation for over a decade, was the choice of the present study on interspecies interactions. Growth and methanation by the enrichment were suppressed in the presence of antibiotics, and no methanogen grown on methanol could be isolated using stringent techniques. The present study confirmed syntrophic metabolic interactions in this enrichment with the isolation of a strain of Pseudomonas sp. The organism had characteristic metabolic versatility in metabolizing a variety of substrates including alcohols, aliphatic acids, amino acids, and sugars. Anaerobic growth was favoured with nitrate in the growth medium. Cells grown anaerobically with methanol, revealed maximal nitrate reductase activity. Constitutive oxidative activity of the membrane system emerged from the high-specific oxygen uptake and nitrate reductase activities of the aerobically and anerobically grown cells respectively. Cells grown anaerobically on various alcohols effectively oxidized methanol in the presence of flavins, cofactor FAD and the methanogenic cofactor F420, suggesting a constitutive alcohol oxidizing capacity. In cells grown anaerobically on methanol, the rate of methanol oxidation with F420 was three times that of FAD. Efficient utilization of alcohols in the presence of F420 is a novel feature of the present study. The results suggest that utilization of methanol by the mixed culture would involve metabolic interactions between the Pseudomonas sp. and the methanogen(s). Methylotrophic, methanogenic partnership involving an aerobe is a novel feature hitherto unreported among anaerobic syntrophic associations and is of ecological significance

Siderophore production by fluorescent pseudomonads colonizing roots of certain crop plants.

Twelve fluorescent Pseudomonas isolates colonizing roots of four crop plants, chilli, cotton, groundnut and soybean, were examined for extracellular siderophore production in different media under iron deficient conditions. While all the organisms produced siderophores, they varied in the quantity of siderophores produced and in their preference to the medium. The siderophores were invariably hydroxamates (pyoverdine) of trihydroxamate type which formed bidentate ligands with Fe III ions.

Influence of metham sodium on suppression of collar rot disease of peanut, in vitro antibiosis, siderophore production and root colonization by a fluorescent pseudomonad strain FPO4.

A hydroxamate type siderophore producing fluorescent Pseudomonas strain, isolated from the rhizoplane of paddy root showing plant growth promoting activity, exhibited a decreased in vitro antibiosis, production of siderophore and suppression of collar rot in presence of metham sodium. Use of herbicide had a detrimental effect on the plant growth promoting activity of this organism. The multiple drug resistant mutant strain derived from this rhizobacteria colonized the roots, but the herbicide application had a negative effect on their population. HPLC analysis of the siderophore showed five peaks of which the peak number three confirmed the antifungal activity.

Estudio comparativo de la sensibilidad in vitro a aminoglucósidos / A comparative study of sensitivity in vitro of aminoglycoside

Se analizó la susceptibilidad in vitro de 6200 cepas bacterianas de gérmenes gramnegativos, aislados de diversos procesos infecciosos en pacientes atendidos en dos Hospitales del Centro Médico ®La Raza¼, con una técnica automatizada y computarizada, hacia diversos antibióticos. Los antibióticos del grupo de los Aminoglucósidos mostraron una mayor actividad antibacteriana que la observada con otros grupos de antimicrobianos estudiados. Los Aminoglucósidos continúan representando una buena alternativa terapéutica particularmente contra los gérmenes gramnegativos adquiridos intrahospitalariamente

Studies on some factors influencing the production of calcium lactobionate by Pseudomonas mucidolens NRRL B-16

The effect of some factors on calcium lactobionate production by P. mucidolens NRRL B-16 using the submerged culture technique was investigated. It was found that optimum yield of calcium lactobionate [65%] was obtained when the culture medium contained [g/L], lactose 100, KH2PO4 0.6, MgSO4.7H2O 0.25, corn steep liquor 5 ml, calcium carbonate 2.5 g/100 ml, 1 ml/100 ml of 20% urea and 3 drops of soybean oil/100 ml as an antiforming agent at an initial pH of 7 after 14 days of incubation at 30C

Studies on the production of maltobionic acid by Pseudomonas mucidolens NRRL B-16 on maltose

The effect of different media, pH value [phosphate buffer], different concentrations of corn steep liquor and urea and different concentrations of maltose at different incubation periods on the production of maltobionic acid by P. mucidolens NRRL B-16 using the submerged culture technique was investigated. It was found that optimum yield of maltobionic acid [51.9%] after incubation periods [14 days] could be secured by providing the using of fermentation medium containing [g/L] 100 maltose, 0.6 KH2PO4, 0.25 MgSO4.7H2O, 5 ml of corn steep liquor and three drops of soybean oil were added to each culture as an antifoaming agent. Separately, 1 ml of sterile 20% urea was added to each culture flask at pH 6.98

Characterization of bacillus polymyxa isolates from different Brazilian soils

Setenta e oito isolados de B. polymyxa foram obtidos de diferentes solos brasileiros com intuito de se identificar estirpes com marcadores geneticos que pudessem ser utilizadas em experimentos de troca gênica nesta espécie de Bacillus. O DNA destes isolados foi extraído e observou-se que 4 deles apresentavam um plasmídio de tamanho semelhante. Trinta e dois isolados (incluindo os 4 contendo plasmídio) foram escolhidos para estudos complementares. Todos eles mostraram-se resistentes à polimixina-B e à bacitracina e sensíveis aos outros 12 antibióticos testados. Todos os isolados produziram uma substância inibitória contra uma estirpe de Staphylococcus aureus RN45O e 7 contra uma estirpe de Pseudomonas sp. Dos 32 isolados, 25 mostraram-se sensíveis ao fago EPy-2, específico para B.polymyxa, e 2 foram capazes de fixar o nitrogênio atomosférico (teste de reduçäo de acetileno). Entretanto, nenhuma destas características acima mencionadas pode ser atribuída à presença do plasmídio, já que isolados curados (sem o plasmídio) apresentavam as mesmas características fenotípicas que aqueles contendo o plasmídio em questäo