Effects of Phenolic Acids on Bulk-Soil and Rhizosphere-Microbial Populations

4 Effects of Phenolic Acids on Bulk-Soil and Rhizosphere-Microbial Populations 

For a more in depth description of these terms see Rovira (1991), Schmidt (1991), Bertin et al. (2003), Walker et al. (2003) Sylvia et al. (2004). In practical terms, microbial populations in the rhizosphere of cucumber seedlings were estimated as follows root systems of each seedling were dipped briefly into 250 ml of sterile deionized water to dislodge large aggregates of soil material. The resulting root 

Blum et al. (2000) isolated bacterial colonies that could utilize phenolic acid as a sole carbon source from Cecil A-horizon soils treated with individual phenolic acids, either p-coumaric acid or vanillic acid, and then tested these isolated bacterial colonies for their ability to utilize only p-coumaric acid, only vanillic acid or both phenolic acids. They found that the majority of isolates ( 72%) could utilize both phenolic acids while a much smaller fraction ( 28%) could only use the phenolic acid with which the soil had been treated. These results suggested that the majority of phenolic acid-utilizing bacteria in soils utilized a range of phenolic acids as a carbon source. Since soils contain a variety of phenolic acids, as well as other organic compounds (Flaig 1971 Paul and Clark 1989 Lavelle and Spain 

2 Plant-Plant Allelopathic Interactions. Phase I The Laboratory 

2 Plant-Plant AUelopathic Interactions. Phase 1 The Laboratory 

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To Determine the Effects of Phenolic Acids on Bulk-Soil and Rhizosphere Microbial Populations (Section 2.4.4)... 

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