Ultrastructural analysis of the intestinal content of earthworm Lumbricus rubellus Hoffm. (Annelida, Lumbricidae).

Gut content sections of the earthworm Lumbricus rubellus, the surrounding soil and casts were studied using transmission electron microscopy. Bacteria, actinomycetes, dead fungi and empty mycelia were observed to occur throughout the gut content. In the foregut and midgut of worms, some bacteria were found to be partially or totally lysed and digested, although were protected by polysaccharides and clay particles. Not only inactive resting forms (spores) or cells protected by capsular polysaccharides and clay particles and/or by plant cellular remnants, but also separate metabolically active and dividing cells were recovered especially in hindgut. The formation of new bacterial microaggregates was noticed in the posterior intestine as well.