Natural Transformation of
            <i>Pseudomonas fluorescens</i>
            and
            <i>Agrobacterium tumefaciens</i>
            in Soil

Demanèche, Sandrine; Kay, Elisabeth; Gourbière, F.; Simonet, Pascal

doi:10.1128/aem.67.6.2617-2621.2001

Cited by 82 publications

(44 citation statements)

References 32 publications

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“…However, strain Y4 was not transformable in our study. While the loss of competence is sometimes a consequence of laboratory propagation, it is also possible that A. actinomycetemcomitans strains may spontaneously acquire and lose transformability in their natural habitat, as has been observed previously for Pseudomonas fluorescens (7).…”

Section: Discussionmentioning

confidence: 98%

Natural Transformation and DNA Uptake Signal Sequences in Actinobacillus actinomycetemcomitans

et al. 2002

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Actinobacillus actinomycetemcomitans is a member of the family Pasteurellaceae and a major causative agent of periodontitis. While several genera from this family are known to be competent for transformation, A. actinomycetemcomitans has yet to be fully characterized. Here we show that the competence of A. actinomycetemcomitans is remarkably similar to that of Haemophilus influenzae. In addition to having a similar frequency of transformation as H. influenzae, A. actinomycetemcomitans competence could also be induced at least 100-fold by cyclic AMP, suggesting that, as in H. influenzae, at least some competence genes are regulated by catabolite repression. Even more intriguing was the discovery of a putative A. actinomycetemcomitans DNA uptake signal sequence (USS) virtually identical to the USS of H. influenzae. Moreover, we provide evidence that this sequence functions in the same capacity as that from H. influenzae; the sequence appears to be required and sufficient for DNA uptake in a variety of assays. Finally, we have taken advantage of this system to develop a simple, highly efficient competence-based method for generating site-directed mutations in the wild-type fimbriated A. actinomycetemcomitans.Actinobacillus actinomycetemcomitans, a gram-negative, facultative, nonmotile coccobacillus, is a major causative agent of localized juvenile periodontitis and other forms of chronic periodontitis (36). Moreover, A. actinomycetemcomitans is transmissible among family members and may persist for long periods (4). A. actinomycetemcomitans can also spread from the oral cavity, causing a variety of nonoral infections (31, 36). Indeed, the genomic DNA of A. actinomycetemcomitans was identified in atherosclerotic lesions (14), suggesting a possible role of this bacterium in cardiovascular disease.Some A. actinomycetemcomitans strains are known to be naturally competent for transformation (23,30). In many bacteria, transformation occurs when cells enter the state of competence. This enables them to take up DNA and incorporate it into their genomes (8, 18). In the best-studied naturally competent gram-negative bacteria, Haemophilus influenzae, Haemophilus parainfluenzae, Neisseria gonorrhoeae, and Neisseria meningitidis, double-stranded donor DNA fragments are preferentially bound into a DNase-resistant state if they contain a short recognition sequence abundant in their own genomes, the uptake signal sequence (USS) (10, 11). Although uptake has been demonstrated elsewhere for A. actinomycetemcomitans in two preliminary studies (23, 30), a quantitative analysis has yet to be performed. In particular, neither of these studies examined any of the requirements for the induction of competence. Nor was a specific DNA uptake sequence requirement for transformation investigated.Because the function of the USS has been assumed to be exclusion of DNAs from other species, different genera were expected to use different USSs. However, only USSs from the very distantly related genera Haemophilus and Neisseria have been characteriz...

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Section: Discussionmentioning

confidence: 98%

Natural Transformation and DNA Uptake Signal Sequences in Actinobacillus actinomycetemcomitans

et al. 2002

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“…As it is unknown to what extent these conditions will induce competence for DNA uptake in the isolates, in situ transformation rates might actually be higher than those measured in this study. It has, for instance, been shown that Pseudomonas fluorescens becomes competent for natural transformation in soil but not in vitro (Demanèche et al, 2001). Induction of competence might be regulated under specific conditions inside plants or on plant surfaces.…”

Section: Discussionmentioning

confidence: 99%

Assessment of transformability of bacteria associated with tomato and potato plants

Overbeek

Ray

Elsas

2007

Environ. Biosafety Res.

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Transformation of plant-associated bacteria by plant DNA has never been demonstrated in agricultural fields. In total 552 bacterial isolates from stems of Ralstonia solanacearum-infected and healthy tomato plants and from stems and leaves of healthy potato plants were tested for natural genetic competence using plasmid pSKTG DNA and homologous DNA extracts. Control strain Acinetobacter baylyi ADP1 was transformable with both DNA extracts. No transformable isolates were observed after treatment with plasmid pSKTG DNA. Two isolates, P34, identified as Pseudomonas trivialis and A19, identified as Pseudomonas fragi, were selected on the basis of the consistently higher Rp-resistant CFU numbers after treatment with DNA from Rp-resistant cells than with that from wild-type cells. P34 showed 2.1-fold and A19 1.5-fold higher Rp-resistant CFU numbers after treatment with DNA from homologous Rp-resistant cells versus that from wild-type cells. It is concluded that bacteria capable of in vitro capture and integration of exogenous DNA into their genomes are relatively rare in culturable bacterial communities associated with tomato and potato plants, or that conditions conducive to transformation were not met in transformation assays.

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“…Al mismo tiempo que pueden transformarse bajo microcosmos en el suelo con un tratamiento físico o químico especifico (DEMANECHE, 2001). …”

Section: Identificación De Bacterias Resistentes a CDunclassified

Resistencia a cadmio (Cd) de bacterias endófitas y bacterias rizosféricas aisladas a partir de Oriza sativa en Colombia

et al. 2017

Rev Colombiana Cienc Anim. RECIA

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The present study had as objective to evaluate in vitro the resistance of endophytic bacteria and rizospheric bacteria to different concentrations of Cadmium.This bacteria were isolated fron different tissues of commercial rice varieties and from bacteria isolated from the rhizosphere in rice plantations of the Nechí (Antioquía) and Achí (Bolivar). Plant growth promotion was evaluated in vitro by nitrogen fixation, phosphate solubilization and siderophores production of endophytic bacteria. Of each tissue isolated from rice plants was carried out isolation in culture medium for endophytic bacteria, and the soil samples were serially diluted in peptone water. Each sample was determined the population density by counting in CFU / g of tissue and morphotypes were separated by shape, color, size and appearance in culture media. Significant differences were observed for density population of bacteria with respect to tissue, with higher values in root (4x10 11 g/root), followed of the stem (3x10 10 g/etem), leaf (5x10 9 g/ leaf), flag leaf (3x10 9 g/ flag leaf) and with less density in panicle (4x10 8 g/panicle). The results of the identification with kit API were confirmed the presence of endophytic bacteria Burkholderia cepaceae and rizospheric bacteria Pseudomona fluorescens With the ability to tolerate different concentrations of Cd, fix nitrogen, solubilize phosphates and produce siderophores. Keywords:Rizospheric bacteria; rizosphere; tolerance; Cd ResumenEl presente estudio tuvo como objetivo evaluar in vitro la resistencia de bacterias endófitas y rizosféricas a diferentes concentraciones de Cadmio (Cd). Se evaluó in vitro la promoción de crecimiento vegetal mediante la fijación de nitrógeno, solubilización de fosfato y producción de sideróforos de bacterias endófitas aisladas de diferentes tejidos de variedades de arroz comerciales y de bacterias aisladas de la rizósfera en las plantaciones de arroz de los corregimientos de Nechí (Antioquía) y Achí (Bolívar). Se colectaron muestras de raíz, tallos y hojas de plantas de arroz y de muestras de suelo rizosférico. A cada muestra se les determinó la densidad poblacional por medio de conteo en UFC/ g de tejido y se separaron morfotipos por forma, color, tamaño y apariencia en medios de cultivos. Se observaron diferencias significativas para densidad poblacional de bacterias con respecto a tejido, con mayores valores en raíz (4x10 11 g/raíz), seguida de tallo (3x10 10 g/tallo), hoja (5x10 9 g/hoja), hoja bandera (3x10 9 g/hoja bandera) y menor densidad en panícula (4x10 8 g/panícula). Los resultados de la identificación con kit API20E confirmaron la presencia de la bacteria endófita Burkholderia cepaceae y la bacteria rizosférica Pseudomona fluorescens con capacidad de tolerar diferentes concentraciones de Cd, fijar nitrógeno, solubilizar fosfatos y producir sideróforos. Palabras Clave:Bacteria endófita; rizósfera; tolerancia; Cadmio

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Natural Transformation of Pseudomonas fluorescens and Agrobacterium tumefaciens in Soil

Cited by 82 publications

References 32 publications

Natural Transformation and DNA Uptake Signal Sequences in Actinobacillus actinomycetemcomitans

Natural Transformation and DNA Uptake Signal Sequences in Actinobacillus actinomycetemcomitans

Assessment of transformability of bacteria associated with tomato and potato plants

Resistencia a cadmio (Cd) de bacterias endófitas y bacterias rizosféricas aisladas a partir de Oriza sativa en Colombia

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