A feeding induced switch from a variable to a homogenous state of the earthworm gut microbiota within a host population.
BACKGROUND
The distribution pattern of the earthworm gut microbiota at the host population level is of fundamental importance to understand host-microbiota interactions. Our current understanding of these interactions is very limited. Since feeding represents a main perturbation of the gut microbiota, we determined the effect of a single dose of feed on the microbiota associated with an earthworm population in a simulated microenvironment.


METHODS
Earthworms were sampled 0, 1 and 7 days after feeding. We determined the overall composition of the earthworm-associated microbiota by 16S rRNA gene cloning and sequencing. Based on the 16S rRNA gene data we constructed quantitative PCR's (Q-PCR) for the seven most dominating bacterial groups.


RESULTS
Q-PCR revealed low density and highly variable microbiota among the earthworms before feeding, while a high-density homologous microbiota resulted from feeding. We found that the microbiota 1 day after feeding was more equal to the microbiota after 7 days than before feeding. Furthermore, we found that the gut microbiota was very distinct from that of the bedding and the feed.


CONCLUSIONS
The homogenous population response represents fundamental new knowledge about earthworm gut associated bacteria.
Rudi
Knut
K
Hedmark University College, Hamar, Norway. knut.rudi@hihm.no
Odegård
Kristin
K
Løkken
Tine Therese
TT
Wilson
Robert
R
D000821:Animal Feed; D000818:Animals; D003001:Cloning, Molecular; D016000:Cluster Analysis; D017143:Fuzzy Logic; D041981:Gastrointestinal Tract / Q000033:anatomy & histology / Q000382:microbiology*; D005798:Genes, Bacterial; D009835:Oligochaeta / Q000033:anatomy & histology* / Q000382:microbiology*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000378:metabolism; D012044:Regression Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D017422:Sequence Analysis, DNA; D013997:Time Factors
D012336:RNA, Ribosomal, 16S