ABSTRACT
Bacterial clone libraries of the gut microbiota of nurtured and starved Cylindroiulus fulviceps specimens displayed the predominance of the phyla Bacteroidetes (55 and 37 %, respectively) and Proteobacteria (40 and 35 %, respectively) and a high similarity to bacteria previously detected in the intestinal tract of termites and beetles, which are known to harbor symbiotic bacteria essential for digestive activity. Bacterial isolates were dominated by Proteobacteria (74 %), followed by members of the phyla Actinobacteria, Firmicutes and Bacteroidetes. PCR-DGGE fingerprints of the gut samples showed that intestinal bacteria were affected by starvation, although the change was not significant.
Subject(s)
Arthropods/microbiology , Bacteria/genetics , Bacteria/isolation & purification , Cloning, Molecular/methods , DNA Fingerprinting/methods , Gastrointestinal Tract/microbiology , Actinobacteria/classification , Actinobacteria/genetics , Actinobacteria/isolation & purification , Animals , Bacteria/classification , Bacteriological Techniques , Bacteroidetes/classification , Bacteroidetes/genetics , Bacteroidetes/isolation & purification , Culture Media , DNA, Bacterial/genetics , Ecosystem , Electrophoresis, Agar Gel/methods , Metagenome , Molecular Sequence Data , Phylogeny , Proteobacteria/classification , Proteobacteria/genetics , Proteobacteria/isolation & purification , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNAABSTRACT
The earthworm, Lumbricus rubellus, plays an essential role in soil ecosystems as it affects organic matter decomposition and nutrient cycling. By ingesting a mixture of organic and mineral material, a variety of bacteria and fungi are carried to the intestinal tract of the earthworm. To get a better understanding of the interactions between L. rubellus and the microorganisms ingested, this study tried to reveal if the diet affects the composition of the gut microflora of L. rubellus or if its intestinal tract hosts an indigenous, species-specific microbiota. A feeding experiment with L. rubellus was set up; individuals were collected in the field, transferred to a climate chamber and fed with food sources of different quality (dwarf shrub litter, grass litter or horse dung) for six weeks. DNA was extracted from the guts of the earthworms, as well as from the food sources and the surrounding soil, and further analysed by a molecular fingerprinting method, PCR-DGGE (Polymerase Chain Reaction -- Denaturing Gradient Gel Electrophoresis). We were able to demonstrate that the gut microbiota was strongly influenced by the food source ingested and was considerably different to that of the surrounding soil. Sequencing of dominant bands of the bacterial DGGE fingerprints revealed a strong occurrence of y-Proteobacteria in all gut samples, independent of the food source. A specific microflora in the intestinal tract of L. rubellus, robust against diet changes, could not be found.
