Spatial homogeneity of abundant bacterial 16S rRNA molecules in grassland soils

The variability of prominent bacterial 16S rRNA molecules from environmental soil samples was investigated. Ribosomes and genomic DNA were extracted from 160 soil samples derived from three different test fields in the Drentse A grasslands (The Netherlands). After amplification of bacterial 16S rRNA molecules by reverse transcription and PCR, the products were separated by temperature-gradient gel electrophoresis. Characteristic and complex band patterns were obtained, indicating high bacterial diversity. The fingerprints from soil samples from plots, taken in regular patterns, were almost identical. Reproducible differences between the three test fields of different history were obtained. A parallel approach with PCR-amplified genomic 16S rDNA led to similar results. The presence and activity of prominent bacteria in test fields of several hundred m(2) were constant. Only one gram of soil was needed to represent the prominent bacteria in large homogeneous grassland areas. The spatial distribution of bacterial ribosomes in soil at this site was homogeneous, suggesting the presence and activity of the dominant soil bacteria was the same.