C. elegans' Microbiome
by Roberto
Not long after participating in the discovery of mRNA and the triplet code, Sydney Brenner set out to study "how genes might specify the complex structures found in higher organisms." Those are the words in the opening sentence of his 1974 foundational paper, which established the nematode Caenorhabditis elegans as a model system for developmental and behavioral genetics. History proved that not only did he choose the right organism, but he also chose the right questions to ask. Today's thriving community of "worm scientists" is testament of his legacy. From the outset he spelled out the strain of C. elegans to use, the composition of the agar medium and even the bacterial food for the worm, a strain of Escherichia coli B. For half a century, C. elegans investigators have used the same strains and growth conditions. In so doing, they have achieved outstanding reproducibility and major advances. All this wonderful science did come at a price; the ecology of the nematode was largely dismissed. But not by all.
Fig. 1. Wild-type C. elegans hermaphrodite stained with the fluorescent dye Texas Red to highlight the nuclei of all cells. Source
For several years, studies on the natural history of C. elegans advanced but somehow, they were out of the limelight. That changed in 2015. As part of a series on the natural history of model organisms published in eLife, Lise Frézal and Marie-Anne Félix wrote an article on "C. elegans outside the Petri dish," describing the worm's natural lifecycles and habitats. While they did not directly spell it out, the article practically shouts out the question: what about C. elegans' microbial partners? Then, in 2016, almost as if the article had served as a catalyst, three groups (Shapira, Schulenburg and Ruvkun) published papers attempting to define the microbiome of C. elegans. Now, each group could have continued working separately. The beauty in this case is that they joined forces and published a joint paper in 2017 synthesizing the significance of their three approaches and outlining the future challenges. And here is the clincher. In 2020 they published the description of "CeMbio — The Caenorhabditis elegans Microbiome Resource" and made the resource widely available. This is a synthetic community of twelve bacterial strains that represent the core microbiome of C. elegans, along with an enormous amount of groundwork characterization of the strains and their interactions with their host. Indeed, a wonderful gift to the scientific community at large. I have been advocating for years that many groups should work on one model synthetic bacterial community. I think this is the one. I am hoping it will attract the attention of many groups worldwide. If that happens, I'll be cheering from the sidelines!
