Metagenomic Exploration of Bacterial Community Structure of Earthworms’ Gut

Samrendra Singh Thakur,Azhar Rashid Lone,Subodh Kumar Jain,Nalini Tiwari,Shweta Yadav

doi:10.22207/jpam.15.3.05

Abstract

Living organisms are naturally bestowed with unique and imitable qualities for maintaining ecological balance and earthworms are no exceptions. These so-called keystone species of terrestrial ecosystems are equipped with wonderful machinery, allowing them to nurture soil beautifully. Earthworm gut represents a potential microbial reservoir, having a complex interdependence with the host. The study aimed to profile bacterial community structure of three earthworm species belonging to two different life forms; Perionyx excavatus and Eudrilus eugeniae (epigeic), Polypheretima elongata (endogeic) respectively. Diversity analysis using 16S amplicon sequencing revealed that the dominant phyla were Proteobacteria (34.17-77.88) followed by Actinobacteria (13.43-35.54%), Firmicutes (1.69-15.45%) and Bacteroidetes (0.51-8.12%). The alpha diversity indices explicit similar gut microbiota of Perionyx excavatus and Eudrilus eugeniae and while higher alpha diversity was recorded in comparison to Polypheretima elongata gut. The taxonomic to the phenotypic annotation of 16S rRNA metagenomes revealed that dominance of Gram-negative bacterial community in all earthworm species while, Polypheretima elongata comprises higher percentage (78%) of Gram-negative bacterial community to Perionyx excavatus (32.3%) and Eudrilus eugeniae (38.3%). The oxygen requirement phenotypic analysis showed that all earthworm species were abundant with aerobic followed by anaerobic bacterial groups. Furthermore, functional metabolism phenotypic analysis revealed that a high abundance of ammonia oxidizers (29.3-80.2%), the gut microbiomes showed the relative abundance of sulphate reducer (22.6-78.7%), nitrite reducer (19.8-73.2%), dehalogenators (12.6-25.1%), illustrating in the role of these microbial communities in various degradation and bioremediation processes. The present study signifies the intrinsic gut microbiota of earthworm species for intensified biodegradation.

Highlights

Earthworms are the most dominant members of terrestrial ecosystems, play vital role in biogeochemical and nutritional rhythm of soil[1,2]
The study aimed to profile bacterial community structure of three earthworm species belonging to two different life forms; Perionyx excavatus and Eudrilus eugeniae, Polypheretima elongata respectively
The phylogenetic position of three query cytochrome oxidase subunit 1 (COI) sequences was based on the BLASTN homology against the nucleotide sequence collection of the NCBI GenBank and BOLD sequence database and were identified as Perionyx excavatus (S1), Eudrilus eugeniae (S2), and Polypheretima elongata (S3)

Summary

Introduction

Earthworms are the most dominant members of terrestrial ecosystems, play vital role in biogeochemical and nutritional rhythm of soil[1,2]. These unsung hero of the soil ecosystems alter the soil texture, regulate water content, maintain the availability of nutrients for the plants[3] and regulate diverse biological functions by mixing the organic matter and other minerals within their gut[4,5]. In addition to shaping the soil structure, biogeochemical cycling and soil organic matter dynamics, earthworms have impacts on microbial communities in their gut, casts and drilosphere[6]. The study evaluated taxonomic and functional profiling of gut microbiome of earthworms of diverse life forms and habitat

Methods

Results

Discussion

Conclusion