2002 Volume 56 Issue 1 Pages 23-29
Structural shifts in soil bacterial communities that occur in response to the addition of catechol to soil were investigated in order to characterize the soils based on response of indigenous bacterial communities to chemical stress. Bacterial numbers in the soils after treatment with catechol (at concentrations of 0.5, 2.0, 5.0, or 10.0 mg/g soil) were determined by the plate count method. Randomly selected isolates were subjected to cluster analysis (UPGMA) on the basis of the utilization pattern of 61 carbon sources (BIOLOG), and the diversity index was calculated using the sum of the distances between each cluster. Bacterial populations and diversity were lower at higher catechol concentrations and increased by the addition of glucose at the concentration of 5.0 mg/g soil. Furthermore, the values of these parameters were lower in the catechol- than in the glucose-treated soils when compared at the same concentration (5.0 mg/g soil), suggesting that catechol exerted a greater selective effect on soil bacterial communities tested than glucose. Principal component analysis of all the bacterial isolates based on the utilization pattern of 31 carbon sources revealed differences among the three test soils in the treatment with catechol and glucose in terms of degree of changes in the isolate composition. These findings suggested that this technique could be useful for the characterization and comparison of the variability of the response of soil bacterial communities to chemical stress. It is recommended that, for the selection of soils used in the test to evaluate the effect of chemicals on the soil microflora, not only physicochemical properties of soils for testing the chemicals but also the variability of the soil microbial communities should be taken into account.
