Transport of a genetically modified Pseudomonas fluorescens and its parent strain through undisturbed tropical soil cores

Guimarães, Vanessa Fernandes; Cruz, Ivanéa V.; Hagler, Allen N.; Mendonça-Hagler, Lêda C.; Elsas, Jan Dirk van

doi:10.1016/s0929-1393(97)00024-3

Cited by 9 publications

(5 citation statements)

References 21 publications

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“…Botelho et al (18) observed no difference in the size, structure and function of bacteria communities analyzed when a strain of P. fluorescens was introduced by seeds of maize. Guimarães et al (47,48) and Araújo et al (4,5,6) observed that a strain of P. fluorescens and its OGM were able to survival and/or colonize bulk soil and rhizosphere of maize. Moënne-Loccoz et al (100) results suggested that the root-associated Pseudomonas community of sugar beet seedlings was resilient to the impact that may be caused by a taxonomically related inoculant.…”

Section: Discussionmentioning

confidence: 99%

Fluorescent Pseudomonads associated with the rhizosphere of crops: an overview

Botelho

Mendonça-Hagler

2006

Braz. J. Microbiol.

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Environmental concerns have led to the need of sustainable use of natural resources. The conventional agriculture caused considerable impacts on soils and waters. It is important to change certain agricultural managements to environmental cleaner techniques. The sustainable agriculture has pointed many approaches and techniques to reduce environmental impact. One of those strategies is the utilization of the soil microbiota to induce plant growth, control of plant diseases and biodegradation of xenobiotic compounds. Studies on the relationship between roots and microbiota are essential to achieve viable agricultural applications. These studies indicate that one of the most abundant microorganisms in the rhizosphere (area around the roots) is fluorescent Pseudomonas spp. They have been considered as an alternative to agrochemicals for controlling plant diseases and increasing plant development. This review addresses the main findings on fluorescent Pseudomonads. It summarizes and discusses significant aspects of this general topic, including (i) rhizosphere as a microhabitat; (ii) taxonomic, genetic and ecological aspects of fluorescent Pseudomonads in the rhizosphere; (iii) mechanisms of Plant Growth Promoting and Biological Control and (iv) commercial use of PGPR in agriculture.

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Section: Discussionmentioning

confidence: 99%

Fluorescent Pseudomonads associated with the rhizosphere of crops: an overview

Botelho

Mendonça-Hagler

2006

Braz. J. Microbiol.

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“…This suggests that under field conditions, the effect of soil structure (i.e., macropores) often overrides the effect of texture on microbial removal. A clay soil core with many cracks and channels might favor microbial transport compared with a sandy soil core with a more homogenous pore structure (Guimaraes et al, 1997). With intact soil cores, there is sometimes no relationship between soil texture and microbial transport (Guimaraes et al, 1997; Smith et al, 1985).…”

Section: Soilsmentioning

confidence: 99%

“…A clay soil core with many cracks and channels might favor microbial transport compared with a sandy soil core with a more homogenous pore structure (Guimaraes et al, 1997). With intact soil cores, there is sometimes no relationship between soil texture and microbial transport (Guimaraes et al, 1997; Smith et al, 1985). Removal rates are more variable (refer to normalized range, NR values in Tables 4 and 7) in soils containing clay and gravels (clayey soil, silty clay loam, clay loam, silt loam‐over‐gravels, and deep silt loam) than fine textured and volcanic soils (silt loam, fine sand loam, recent sandy soil, allophanic soil, and pumice sand soils). For a specific soil, the removal rate for fecal coliforms is generally greater than that for bacteriophages, but they are within the same order of magnitude.…”

Section: Soilsmentioning

confidence: 99%

“…In uncontaminated large‐pored media where there is no straining, the linear‐log relationship is evident even on a laboratory scale, for example, in an 8 m long column filled with pea gravel (Close et al, 2006). The linear‐log relationship is shown even during microbial transport though 30‐cm long intact soil cores comprising uncontaminated clay soils (Guimaraes et al, 1997).…”

Section: Removal With Distance: Log (Cp/c0) – X Functionsmentioning

confidence: 99%

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Microbial Removal Rates in Subsurface Media Estimated From Published Studies of Field Experiments and Large Intact Soil Cores

2009

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Information about the microbial removal efficiencies of subsurface media is essential for assessing the risk of water contamination, estimating setback distances between disposal fields and receiving waters, and selecting suitable sites for wastewater reclamation. By analyzing published data from field experiments and large intact soil cores, an extensive database of microbial removal rates was established for a wide range of subsurface media. High microbial removal rates were found in volcanic soils, pumice sand, fine sand, and highly weathered aquifer rocks. Low removal rates were found in structured clayey soils, stony soils, coarse gravel aquifers, fractured rocks, and karst limestones. Removal rates were lower for enteroviruses than for other human viruses; for MS2 phage than for other phage species; for waste-associated microbes than for those cultivated in the laboratory; and for contaminated media than for uncontaminated media. Microbial removal rates are inversely correlated with infiltration rates and transport velocity. The assumption of first-order law, or a constant removal rate (when the transport scale reaches a representative elementary volume), is appropriate for most of field data analyzed. However 30% of the datasets (26 out of 87 pairs) are better described with the power law, implying reduced removal rates with transport distance. The latter is most prominent for organically contaminated media, especially in relatively fine aquifer media. The presence of organic matter, heterogeneity in microbial properties, change in solution chemistry, detachment, and physical straining, may have caused the discrepancies from the first-order law traditionally used in transport models for describing microbial removal.

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“…In contrast, when Soil 2 is packed into the column, the bacterial effluent concentration in the first 40 min reach around 80% of the constant influent concentration. It was tested in long experiments that the effluent concentration slowly reaches the influent concentration, reaching 95% in 4 h. The differences observed could be due to several causes: soil surface chemical composition or electrical properties (Scholl and Harvey, 1992;Scholl et al 1990), organic content (Guimaraes et al 1997;Johnson and Logan, 1996) or grain size (Sharma and McInerney, 1994). A further possible parameter affecting retention could be the presence of physical heterogeneities (Tufenjki and Elimelech, 2004), such as those observed in Soil 1 (see Fig.…”

Section: E Coli Attachment Onto Porous Media Clean Bed Collision Efmentioning

confidence: 99%