Role of biotic factors in the control of soil-borne fungi by fluorescent pseudomonads

Elsherif, Mohamed; Grossmann, F.

doi:10.1016/s0944-5013(96)80003-6

Cited by 13 publications

(11 citation statements)

References 29 publications

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“…This may reflect adaptations to different niches. Moreover, when cabbage was inoculated with fluorescent pseudomonads, an increase in the number of recoverable rhizosphere bdellovibrios able to use this group of bacteria was detected (8). The possibility that the root-associated bdellovibrios examined in this study originated from the seeds and developed along with the root bacterial populations cannot be ruled out as members of the genus Bdellovibrio have been shown to survive in dry soil for extended periods (10), probably in association with soil particles.…”

Section: Discussionmentioning

confidence: 73%

Prey Range Characterization, Ribotyping, and Diversity of Soil and Rhizosphere Bdellovibrio spp. Isolated on Phytopathogenic Bacteria

Jurkevitch

Minz

Ramati

et al. 2000

Appl Environ Microbiol

161

152

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Thirty new Bdellovibrio strains were isolated from an agricultural soil and from the rhizosphere of plants grown in that soil. Using a combined molecular and culture-based approach, we found that the soil bdellovibrios included subpopulations of organisms that differed from rhizosphere bdellovibrios. Thirteen soil and seven common bean rhizosphere Bdellovibrio strains were isolated when Pseudomonas corrugata was used as prey; seven and two soil strains were isolated when Erwinia carotovora subsp. carotovora and Agrobacterium tumefaciens, respectively, were used as prey; and one tomato rhizosphere strain was isolated when A. tumefaciens was used as prey. In soil and in the rhizosphere, depending on the prey cells used, the concentrations of bdellovibrios were between 3 ؋ 10 2 to 6 ؋ 10 3 and 2.8 ؋ 10 2 to 2.3 ؋ 10 4 PFU g ؊1 . A prey range analysis of five soil and rhizosphere Bdellovibrio isolates performed with 22 substrate species, most of which were plant-pathogenic and plant growth-enhancing bacteria, revealed unique utilization patterns and differences between closely related prey cells. An approximately 830-bp fragment of the 16S rRNA genes of all of the Bdellovibrio strains used was obtained by PCR amplification by using a Bdellovibrio-specific primer combination. Soil and common bean rhizosphere strains produced two and one restriction patterns for this PCR product, respectively. The 16S rRNA genes of three soil isolates and three root-associated isolates were sequenced. One soil isolate belonged to the Bdellovibrio stolpii-Bdellovibrio starrii clade, while all of the other isolates clustered with Bdellovibrio bacteriovorus and formed two distantly related, heterogeneous groups.Bdellovibrio spp. are small, very motile gram-negative bacteria that exhibit a unique and obligate requirement for other gram-negative cells, which they invade and use as substrates (22). These organisms were first isolated from soil (25), where they are commonly encountered. They can also be found in freshwater, brackish water, seawater, sewage, water pipes, and water reservoirs (13,22). It has been shown that marine Bdellovibrio species preferentially associate with surfaces, where they are components of biofilms (13,31).The biphasic growth cycle of Bdellovibrio species includes a free-swimming attack phase and an intraperiplasmic growth phase; this growth cycle distinguishes this group of bacteria from all other bacterial parasites of bacteria (29). Three Bdellovibrio species, Bdellovibrio bacteriovorus, Bdellovibrio stolpii, and Bdellovibrio starrii, were described first on the basis of their GϩC contents and DNA relative association data (23, 26) and then on the basis of 16S rRNA analysis data (6). Because of the large distances between the species, Baer et al. (2) recently proposed that the genus should be split and the new genus Bacteriovorax should be created and should include two species, Bacteriovorax starrii and Bacteriovorax stolpii.

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Section: Discussionmentioning

confidence: 73%

Prey Range Characterization, Ribotyping, and Diversity of Soil and Rhizosphere Bdellovibrio spp. Isolated on Phytopathogenic Bacteria

Jurkevitch

Minz

Ramati

et al. 2000

Appl Environ Microbiol

161

152

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“…Pseudomonas fluorescens are grazed by predatory bacteria, protozoa, and bacterivorous nematodes (Elsherif and Grossmann, 1996). For bacterivores there is a clear potential direct effect on P. fluorescens abundance via grazing.…”

Section: Interactions Between Pseudomonas and Bacterivores And Decompmentioning

confidence: 99%

Getting the ecology into interactions between plants and the plant growth-promoting bacterium Pseudomonas fluorescens

Hol¹,

Bezemer²,

Biere³

2013

Front. Plant Sci.

119

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Plant growth-promoting rhizobacteria (PGPR) are increasingly appreciated for their contributions to primary productivity through promotion of growth and triggering of induced systemic resistance in plants. Here we focus on the beneficial effects of one particular species of PGPR (Pseudomonas fluorescens) on plants through induced plant defense. This model organism has provided much understanding of the underlying molecular mechanisms of PGPR-induced plant defense. However, this knowledge can only be appreciated at full value once we know to what extent these mechanisms also occur under more realistic, species-diverse conditions as are occurring in the plant rhizosphere. To provide the necessary ecological context, we review the literature to compare the effect of P. fluorescens on induced plant defense when it is present as a single species or in combination with other soil dwelling species. Specifically, we discuss combinations with other plant mutualists (bacterial or fungal), plant pathogens (bacterial or fungal), bacterivores (nematode or protozoa), and decomposers. Synergistic interactions between P. fluorescens and other plant mutualists are much more commonly reported than antagonistic interactions. Recent developments have enabled screenings of P. fluorescens genomes for defense traits and this could help with selection of strains with likely positive interactions on biocontrol. However, studies that examine the effects of multiple herbivores, pathogens, or herbivores and pathogens together on the effectiveness of PGPR to induce plant defenses are underrepresented and we are not aware of any study that has examined interactions between P. fluorescens and bacterivores or decomposers. As co-occurring soil organisms can enhance but also reduce the effectiveness of PGPR, a better understanding of the biotic factors modulating P. fluorescens–plant interactions will improve the effectiveness of introducing P. fluorescens to enhance plant production and defense.

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“…Other predatory bacteria that are found in rhizosphere soil are the Bdellovibrio and like organisms (BALOs). BALOs have been isolated from the rhizosphere of common bean (Phaseolus vulgaris), tomato (Lycopersicon esculentum; Jurkevitch 2007), Chinese cabbage (Brassica campestris; Elsherif and Grossmann 1996), strawberry (Fragaria ananassa), pepper (Capsicum annum L.), Lily of the valley (Convallaria majalis L.; Markelova and Kershentsev 1998) and soybean (Glycine max; Scherff 1973). BALOs are gram negative, obligate predators of other bacteria; they seem to be ubiquitous in soil and are commonly found in very different environments (Jurkevitch 2007).…”

Section: Bacteriamentioning

confidence: 99%

“…Since BALO isolates can differ in prey ranges (Jurkevitch 2007), BALO populations may be altered by changes affecting the community structure of rhizobacterial communities at large. An increase in rhizosphere BALOs able to prey upon rhizobacterial fluorescent pseudomonads following an increase in population levels of the latter perhaps reflects such interactions (Elsherif and Grossmann 1996). Predator-prey interactions between rhizobacteria may thus be a significant-yet largely ignoredcontributing force in the rhizosphere.…”

Section: Bacteriamentioning

confidence: 99%

The rhizosphere zoo: An overview of plant-associated communities of microorganisms, including phages, bacteria, archaea, and fungi, and of some of their structuring factors

Buée¹,

Boer

Martin³

et al. 2009

Plant Soil

411

236

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Role of biotic factors in the control of soil-borne fungi by fluorescent pseudomonads

Cited by 13 publications

References 29 publications

Prey Range Characterization, Ribotyping, and Diversity of Soil and Rhizosphere Bdellovibrio spp. Isolated on Phytopathogenic Bacteria

Prey Range Characterization, Ribotyping, and Diversity of Soil and Rhizosphere Bdellovibrio spp. Isolated on Phytopathogenic Bacteria

Getting the ecology into interactions between plants and the plant growth-promoting bacterium Pseudomonas fluorescens

The rhizosphere zoo: An overview of plant-associated communities of microorganisms, including phages, bacteria, archaea, and fungi, and of some of their structuring factors

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