Skip to main content

Characterization of Bacillus and Pseudomonas strains with suppressive traits isolated from tomato hydroponic-slow filtration unit

Buy Article:

$50.00 plus tax (Refund Policy)

Abstract:

Bacillus and Pseudomonas spp. are known to be involved in plant pathogenic fungi elimination during the slow filtration process used in tomato soilless cultures. We isolated 6–8 strains of both Bacillus and Pseudomonas from the top, middle, and bottom sections of filters and identified them after 16S rDNA sequencing. Four Pseudomonas strains were identified as Pseudomonas fulva, 5 as Pseudomonasplecoglossicida, and 12 as Pseudomonas putida. The use of specific oligonucleotide polymerase chain reaction primer sets designed from gyrB gene sequences additionally permitted the identification of 17 Bacilluscereus and 3 Bacillus thuringiensis strains. Ribotyping with EcoRI pointed out an important polymorphism within Bacillus and Pseudomonas strains. Molecular characterization did not reveal a correlation between the location of isolates within the filter (top, middle, or bottom) and bacterial identification or riboclusters. Functional aspects assessed by community-level physiological profiling showed marked phenotypic differences between Pseudomonas communities isolated from the top and bottom filter layers; differences were lower between Bacillus communities of different layers and far less noticeable between mixed communities of Bacillus and Pseudomonas. These strains were tested for several suppressive activities. Conversely to most Bacillus, the majority of Pseudomonas strains were auxin producers and promoted the growth of tomato plantlet roots. On the other hand, only Bacillus strains displayed antagonistic activities by inhibiting the growth of pathogenic fungi frequently detected in soilless cultures. Siderophores were produced by nearly all bacteria, but at higher amounts by Pseudomonas than Bacillus strains. The biocontrol agent potentiality of certain strains to optimize the slow filtration process and to promote the suppressive potential of nutrient solution is discussed.

Les espèces Bacillus and Pseudomonas sont connues pour leur implication dans l’élimination de champignons pathogènes de plantes lors du processus de filtration lente utilisé en cultures hors-sol. Nous avons identifié par séquençage de l’ADNr-16S plusieurs souches isolées à différentes profondeurs dans un filtre (6–8 souches de Bacillus and 6–8 Pseudomonas dans le haut, milieu and bas). Parmi les Pseudomonas, 4 souches ont été identifiées comme étant Pseudomonas fulva, 5 comme étant Pseudomonas plecoglossicida and 12 comme étant Pseudomonas putida. De plus, l’utilisation d’une PCR spécifique à partir d’oligonucleotides issus du gène gyrB a permis d’identifier 17 souches de Bacillus cereus and 3 de Bacillus thuringiensis. Le ribotypage avec EcoRI a mis en évidence un important polymorphisme chez les souches de Bacillus and Pseudomonas. La caractérisation moléculaire des isolats n’a pas permis d’établir une corrélation entre leurs localisations dans le filtre (haut, milieu, bas) and leur identification ou appartenance à un ribogroupe. Les aspects fonctionnels des souches ont été estimés par la méthode des «profils physiologiques au niveau de communautés» qui montra d’importantes différences phénotypiques entre les communautés de Pseudomonas isolées du haut and du bas du filtre ; les différences étaient moins élevées entre les communautés de Bacillus and peu notable entre les communautés mélangées de Bacillus and Pseudomonas. Plusieurs activités suppressives ont été recherchées chez les souches bactériennes. Contrairement à la plupart des Bacillus, la majorité des Pseudomonas produisent des auxines and promeut la croissance des jeunes plantes de tomate. En revanche, seules les souches de Bacillus ont une activité antagoniste and inhibent la croissance de champignons pathogènes fréquemment détectés en cultures hors-sol. Des sidérophores sont produits par presque toutes les bactéries, mais à un taux plus élevé chez les Pseudomonas par rapport aux souches de Bacillus. Les potentialités d’agent de lutte biologique de certaines souches pour optimiser le processus de filtration lente and promouvoir le potentiel suppressif des solutions nutritives sont discutées.

Document Type: Research Article

Publication date: June 1, 2007

More about this publication?
  • Published since 1954, this monthly journal contains new research in the field of microbiology including applied microbiology and biotechnology; microbial structure and function; fungi and other eucaryotic protists; infection and immunity; microbial ecology; physiology, metabolism and enzymology; and virology, genetics, and molecular biology. It also publishes review articles and notes on an occasional basis, contributed by recognized scientists worldwide.
  • Information for Authors
  • Submit a Paper
  • Subscribe to this Title
  • Terms & Conditions
  • Sample Issue
  • Reprints & Permissions
  • ingentaconnect is not responsible for the content or availability of external websites
nrc/cjm/2007/00000053/00000006/art00013
dcterms_title,dcterms_description,pub_keyword
6
5
20
40
5

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
X
Cookie Policy
ingentaconnect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more