C. elegans nematodes are shown to have a long-lasting microbiome composition

Oscar Solberg

Overview

C. elegans is a common model organism, as their translucent anatomy, ease of culture, and short life cycle make them an easily observable, low-maintenance subject for experimentation. With the rising interest in the human microbiome, interest in the C. elegans microbiome has seen a parallel but somewhat protracted rise. There have been relatively few studies on whether the C. elegans intestinal microbiome is stable or transient. This investigation wished to evaluate the duration in which bacteria eaten by C. elegans remained in their guts. C. elegans were fed teal fluorescent bacteria for three to six days, followed by orange bacteria for about 90 minutes, and then photographed to gauge the ratio of the two strains of bacteria in the guts of the nematodes. Two control groups were fed only teal fluorescent bacteria or no fluorescent bacteria at all, over the same periods of time. Photos of C. elegans were taken each day using a Nightsea™ stereo microscope fluorescence adapter and fluorescence density was measured in each picture using FIJI. The orange fluorescence was measured in the group fed no fluorescent bacteria as well as the experimental group so that a ratio could be used in data analysis. The ratio made up for differences in the height of the agar between plates and slight differences in light positioning, as well as provided a potential ratio of different bacteria within the guts of the C. elegans of the experimental group. It was found that the ratio of the two bacteria varied by a statistically insignificant amount over the course of the experiment, not only in the experimental group but also in both groups not fed orange fluorescent bacteria. This suggests that the microbiome is a somewhat permanent construct, as the composition of the C. elegans’ microbiomes did not change over time no matter what they were fed and for how long. Further studies might perform the same study with longer time periods, or feed the C. elegans orange fluorescent bacteria for the same amount of time that they are fed teal fluorescent bacteria. As the C. elegans has a roughly analogous physiology to humans, this data might inform the frequency with which microbiome treatments, such as fecal transplants, are performed.

From the student

C. elegans is a common model organism, as their translucent anatomy, ease of culture, and short life cycle make them an easily observable, low-maintenance subject for experimentation. With the rising interest in the human microbiome, interest in the C. elegans microbiome has seen a parallel but somewhat protracted rise. There have been relatively few studies on whether the C. elegans intestinal microbiome is stable or transient. This investigation wished to evaluate the duration in which bacteria eaten by C. elegans remained in their guts. C. elegans were fed teal fluorescent bacteria for three to six days, followed by orange bacteria for about 90 minutes, and then photographed to gauge the ratio of the two strains of bacteria in the gut of the nematodes. Two control groups were fed only teal fluorescent bacteria or no fluorescent bacteria at all, over the same periods of time. Photos of C. elegans were taken each day using a Nightsea™ stereo microscope fluorescence adapter and fluorescence density was measured in each picture using FIJI. The orange fluorescence was measured in the group fed no fluorescent bacteria as well as the experimental group so that a ratio could be used in data analysis. The ratio made up for differences in the height of the agar between plates and slight differences in light positioning, as well as provided a potential ratio of different bacteria within the guts of the C. elegans of the experimental group. It was found that the ratio of the two bacteria varied by a statistically insignificant amount over the course of the experiment, not only in the experimental group but also in both groups not fed orange fluorescent bacteria. This suggests that the microbiome is a somewhat permanent construct, as the composition of the C. elegans’ microbiomes did not change over time no matter what they were fed and for how long. Further studies might perform the same study with longer time periods, or feed the C. elegans orange fluorescent bacteria for the same amount of time that they are fed teal fluorescent bacteria. As the C. elegans has a roughly analogous physiology to humans, this data might inform the frequency with which microbiome treatments, such as fecal transplants, are performed.