A natural microbiome of Caenorhabditis elegans

Abstract

This abstract contains text that is based closely on, or identical to, text found in my poster Sneathen, A Natural Microbiota of Caenorhabditis elegans, Poster Session, Summer Undergraduate Research Program 2015. A community of bacteria that colonizes another organism is referred to as its microbiota. Recent studies have implicated a dramatic impact of the human microbiota on the health status of individuals, including influences on metabolism, the immune system, and behavior. A highly tractable model system for researching the consequences of changes within the microbiota is lacking. Recently, Caenorhabditis elegans, a transparent soil nematode, has been used in microbiota research. C. elegans are typically maintained in the laboratory on monocultures of the bacterium Escherichia coli, which functions as a food source and also constitutes the microbiota. While this lab diet restricts the contact between microorganisms and the nematode to a single bacterial species, interactions between C. elegans and its natural environment are poorly understood. To inform future studies on C. elegans microbiota research, we have sought to define a natural microbiota for C. elegans. As C. elegans were originally isolated from rotten fruit, we grow sterilized C. elegans in compost samples to inoculate them with bacteria they could encounter in their natural habitat. After recovering the nematodes from the compost, we extract DNA and determine the identity of bacteria that have colonized their intestines by 16S rRNA sequencing. The nematode microbiota is compared to the bacterial community found in the compost sampled in parallel. Metagenomic analyses show that the order Bacillales dominates the C. elegans microbiota at the expense of other orders. Previous research on the impact of Bacillus spp. on the health of C. elegans suggests implications of this trend.