3. Results
3.1. Taxonomic annotation of earthworm gut microbiomes
The gut metagenomic 16S rDNA clonal libraries from E. foetida (67 clonal sequences) and P. excavatus (75 clonal sequences) were submitted to the NCBI Genbank and Accession numbers generated (E. foetida clonal sequences KM840923–KM840986, P. excavatus clonal sequences KM840851–KM840922). E. foetida gut metagenomic clonal library was classified into 9 OTUs, whereas the information from P. excavatus was classified into 12 OTU’s (Tables 1 and 2). In total, 96 clonal sequences from each of the earthworm gut 16S rDNA libraries were obtained after sequenc- ing, after chimaera checking, 67 chimaera free sequences from E. foetida and 75 from P. excavatus was obtained. The taxonomic annotations of the sequence datasets were performed by using MG-RAST (Metagenomics Analysis Server). The phylogenetic tree was created indicating the relative abundances of various representative taxa from the gut metagenome of E. foetida and P. excavatus as stack bar chart, the colour coding of the genus was on the basis of their classes (Fig. 1a), the distribution of various phylum on the basis of hits per bacterial sequence in the metagenomes of E. foetida and P. excavatus is represented as pie chart (Fig. 1b). Most num- ber of sequences was annotated to unclassified bacteria (59% in P. excavatus and 47% in case of E. foetida). The next most abundant phylum was Firmicutes representing 15% of clones in P. excavatus and 20% in E. foetida gut. Verrucomicrobia and Chloroflexi were not found in the gut of P. excavatus, but abundant in E. foetida, similarly Spirochaetes were abundant in P. excavatus but not in E. foetida. The taxonomic abundance of the profiles were statistically analyzed. Fisher exact t-test was used and results are represented as extended error bar plot (Fig. 2), which illustrated the relative abundance of various genera representatives in the earthworm gut metagenome. The extended error bar plot depicts significance of the relative abundance of various genera representative of the earthworm gut metagenome. From the extended error bar plot, all the “P-values” were found to be more than 0.05 for the relative abundance of the various bacterial genera, which means that the abundance of vari- ous bacterial representatives from the E. foetida and P. excavatus gut metagenome were almost similar and no specific bacterium/genera is significantly affecting the overall gut bacterial community structure.