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Holmes, M.T., E.R. Ingham, J.D. Doyle, Charles W. Hendricks. 1999. Effects of Klebsiella planticola SDF20 on soil foodweb organisms and wheat growth in sandy soil. Applied Soil Ecology 11:67-78. NHEERL-COR 2075J.

The potential for ecological effects to occur after the release of genetically engineered microorganisms is a global concern and the release of biotechnology products must be assessed on a case-by-case basis. In this research, a genetically engineered strain of Klebsiella planticola (SDF20) bacteria was added to microcosms containing sandy soil and wheat plants to assess the potential for effects on soil biota and plant growth. One half of the soil treatments in this study contained wheat plants to compare some effects on growing rhizosphere communities in the experimental system. When SDF20 was added to soil with plants, the numbers of bacterial and fungal feeding nematodes increased significantly, coinciding with death of the plants. In contrast, when the parental strain, SDF15 was added to soil with plants, only the number of bacterial feeding nematodes increased, but the plants did not die. The introduction of either SDF15 or SDF20 strains to soil without plants did not alter the nematode community. No effects were observed on the activity of native bacterial and fungal communities by either SDF15 or SDF20. This study is evidence that SDF20 can persist under conditions found in some soil ecosystems and for long enough periods of time to stimulate change in soil biota that could affect nutrient cycling processes. Further investigation is needed to determine the extent these observations may occur in situ but this study using soil microcosms was the first step in assessing potential for the release of genetically engineered microorganisms to result in ecological effects.

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