Midgut microbiota of two earthworms pheretima posthuma and eisenia fetida-a metagenomic approach

Earthworms are friends to mankind from time immemorial and are said to be farmers with friends. Among the soil invertebrates, earthworms play an essential role in carbon turnover, nitrogen mineralization, soil formation, cellulose degradation and humus accumulation etc. Nowadays, it is well known, that earthworms and other soil macrofauna modify the soil physical properties and affect soil organic matter decomposition and regulate carbon fluxes and nitrogen cycling. The present study was aimed to study the bacterial diversity of two earthworm species Pheretima posthuma and Eisenia fetida using metagenomic sequencing tools. Metagenomic DNA was isolated from the supplied earthworm gut sample by using c-TAB and Phenol: Chloroform Extraction method followed by AMPure XP bead purification. 1µl of sample was loaded in NanoDrop for determining A260/280 ratio. QC pass DNA samples were processed for first Amplicon generation followed by NGS Library Preparation Using Nextera XT Index Kit (Illumina inc.). The mean of the library fragment size distribution are 594bp and 592bp for sample 1A and sample 2A for Pheretima posthuma and Eisenia fetida respectively. Proteobacteria is predominant in both the earthworm species followed by Cyanobacteria, Actinobacteria, Firmucutes, Planctomycetes, TM7, Verrucomicrobia species. The earthworm gut metagenomes exhibited varied functional attributes like cellulose degradation, aromatics remediation, nitrogen fixation, denitrification, sulphur oxidation and reduction. Hence from the present study it can be concluded that bacterial species plays a vital role in the gut of earthworm and is a natural selection process and earthworm can be used for various process of degradation, pollution control and bioremediation process and the determinant of the species is in the order of group-habitat-species.