Soil microbial communities from the alimentary canal of the earthworm Lumbricus terrestris (Oligochaeta: Lumbricidae)

The effect of earthworm (Lumbricus terrestris) activity on microbial community composition was investigated in a silt loam soil. Fingerprints were constructed using PCR amplicons of bacterial 16S rDNA separated by denaturing gradient gel electrophoresis. Analysis of similarity established that significant differences existed between community fingerprints. Differences were explored using non-metric multidimensional scaling (MDS) and unweighted pair-group method with arithmetic mean (UPGMA). Microbial communities of earthworm casts separated from soil treatments for both CD DGGE and CI DGGE profiles. Cast communities were determined by the worm's food source. Soils with earthworms and manure separated from all other soil treatments. Major trends observed above also were evident in separate analyses employing PCR amplification of nirK for DGGE, and BIOLOG ECO MicroPlates(TM) for community level physiological profiles (CLPP). Data suggest bacterial communities are modified after ingestion, however resultant changes in the soil bacterial community only occur when earthworms consume a soil manure mixture.