Relationship between the number of bacteria added to soil or seeds and their abundance and distribution in the rhizosphere of alfalfa

Hatzinger, Paul B.; Alexander, Martin

doi:10.1007/bf00009496

Cited by 25 publications

(11 citation statements)

References 21 publications

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“…Pseudomonas ST41 has many of the characteristics required to carry out this function and should be considered a candidate micro‐organism for further trials. However, Hatzinger and Alexander (1994) showed that single species inocula may be unreliable. A microbiological cocktail of native Antarctic hydrocarbon degrading bacteria with additional fertilization may be the best solution (e.g.…”

Section: Discussionmentioning

confidence: 99%

Low temperature bioremediation of oil-contaminated soil using biostimulation and bioaugmentation with a Pseudomonas sp. from maritime Antarctica

et al. 2005

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Aims: To identify native Antarctic bacteria capable of oil degradation at low temperatures. Methods and Results: Oil contaminated and pristine soils from Signy Island (South Orkney Islands, Antarctica) were examined for bacteria capable of oil degradation at low temperatures. Of the 300 isolates cultured, Pseudomonas strain ST41 grew on the widest range of hydrocarbons at 4°C. ST41 was used in microcosm studies of low temperature bioremediation of oil‐contaminated soils. Microcosm experiments showed that at 4°C the levels of oil degradation increased, relative to the controls, with (i) the addition of ST41 to the existing soil microbial population (bioaugmentation), (ii) the addition of nutrients (biostimulation) and to the greatest extent with (iii) a combination of both treatments (bioaugmentation and biostimulation). Addition of water to oil contaminated soil (hydration) also enhanced oil degradation, although less than the other treatments. Analysis of the dominant species in the microcosms after 12 weeks, using temporal temperature gradient gel electrophoresis, showed Pseudomonas species to be the dominant soil bacteria in both bioaugmented and biostimulated microcosms. Conclusions: Addition of water and nutrients may enhance oil degradation through the biostimulation of indigenous oil‐degrading microbial populations within the soil. However, bioaugmentation with Antarctic bacteria capable of efficient low temperature hydrocarbon degradation may enhance the rate of bioremediation if applied soon after the spill. Significance and Impact of the Study: In the future, native soil bacteria could be of use in bioremediation technologies in Antarctica.

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Section: Discussionmentioning

confidence: 99%

Low temperature bioremediation of oil-contaminated soil using biostimulation and bioaugmentation with a Pseudomonas sp. from maritime Antarctica

et al. 2005

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“…Entrapment of bacteria in granular peat or polymer gels (32), optimization of the inoculum density (11), and pregermination of seeds (5) have been shown to improve root colonization by seed-associated bacteria. However, previous studies examining the importance of the presowing state have focused on individual strains, and knowledge of the root colonization capacity of broad bacterial groups is lacking.…”

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confidence: 99%

Bacterial Origin and Community Composition in the Barley Phytosphere as a Function of Habitat and Presowing Conditions

Normander

Prosser

2000

Appl Environ Microbiol

143

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An understanding of the factors influencing colonization of the rhizosphere is essential for improved establishment of biocontrol agents. The aim of this study was to determine the origin and composition of bacterial communities in the developing barley (Hordeum vulgare) phytosphere, using denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA genes amplified from extracted DNA. Discrete community compositions were identified in the endorhizosphere, rhizoplane, and rhizosphere soil of plants grown in an agricultural soil for up to 36 days. Cluster analysis revealed that DGGE profiles of the rhizoplane more closely resembled those in the soil than the profiles found in the root tissue or on the seed, suggesting that rhizoplane bacteria primarily originated from the surrounding soil. No change in bacterial community composition was observed in relation to plant age. Pregermination of the seeds for up to 6 days improved the survival of seed-associated bacteria on roots grown in soil, but only in the upper, nongrowing part of the rhizoplane. The potential occurrence of skewed PCR amplification was examined, and only minor cases of PCR bias for mixtures of two different DNA samples were observed, even when one of the samples contained plant DNA. The results demonstrate the application of culture-independent, molecular techniques in assessment of rhizosphere bacterial populations and the importance of the indigenous soil population in colonization of the rhizosphere.The use of antagonistic bacteria for the protection of crops against soilborne pathogens provides a promising environment-friendly alternative to chemical pesticides. However, the root colonization efficiency of introduced biocontrol strains is often limited, potentially reducing the effectiveness of protection (8,25,32). The selection and use of biocontrol strains therefore depend heavily on our knowledge of survival of the inoculant and its potential activity in the rhizosphere ecosystem of a particular plant and soil. Consequently, successful biological control with inoculated strains requires an understanding of the dynamics and composition of the bacterial communities colonizing the rhizosphere.Previous studies, employing cultivation-based, laboratory methods or microscopy, have shown that different bacterial populations are present or active at different stages of root development and that rhizosphere communities are distinct from those found in bulk soil (1,14,17,19,21,27,30). However, recent molecular studies involving PCR amplification of 16S rRNA genes (rDNA), question some of these results. Duineveld et al. (9) reported that the bacterial communities of the Chrysanthemum rhizosphere, as measured by denaturing gradient gel electrophoresis (DGGE) of 16S rDNA PCR products, changed very little with plant age and were similar to those of bulk soil. In contrast, different bacterial communities were identified in soil and in the root tissue of white clover and ryegrass by cluster analysis of a 16S rDNA clone library (16). Furthermore, DGG...

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“…The antagonist survived well in rootfree sand after the suspension had been mixed into the sand (Kortemaa et al 1997). Hatzinger and Alexander (1994) showed that the bacteria which survived well in nonsterile soil were present in the highest population densities in the rhizosphere. Bahme and Schroth (1987) noted that the bacteria which survived in nonrhizosphere soil have good potential as biocontrol agents because the bacteria can await the emerging seed in the soil.…”

Section: Discussionmentioning

confidence: 99%

Effect of soil-spraying time on root-colonization ability of antagonistic Streptomyces griseoviridis

Kortemaa

Haahtela

Smolander

1997

AFSci

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The root-colonization ability of Streptomyces griseoviridis Anderson et al. was tested on turnip rape (Brassica rapa subsp. oleifera DC.) and carrot ( Daucus carota L.) by the sand-tube method. Nonsterile sand was sprayed with a microbial suspension immediately or 7 days after the seed had been sown. Results expressed as population frequencies and densities indicated that S. griseoviridis effectively colonizes the rhizosphere when the microbe is applied immediately after sowing but less effectively when it is applied 7 days later. Detection values of S. griseoviridis were higher for turnip rape than for carrot. In sterile sand, S. griseoviridis invaribly colonized the rhizosphere of turnip rape after each of the two applications. These findings indicate that S. griseoviridis can compete with indigenous soil microbes in the rhizosphere if it is sufficiently abundant in the soil before the seed emerges.If applied later, however, it competes rather poorly. In root-free nonsterile sand, S. griseoviridis dispersed and survived well.

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Relationship between the number of bacteria added to soil or seeds and their abundance and distribution in the rhizosphere of alfalfa

Cited by 25 publications

References 21 publications

Low temperature bioremediation of oil-contaminated soil using biostimulation and bioaugmentation with a Pseudomonas sp. from maritime Antarctica

Low temperature bioremediation of oil-contaminated soil using biostimulation and bioaugmentation with a Pseudomonas sp. from maritime Antarctica

Bacterial Origin and Community Composition in the Barley Phytosphere as a Function of Habitat and Presowing Conditions

Effect of soil-spraying time on root-colonization ability of antagonistic Streptomyces griseoviridis

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