Using single-worm data to quantify heterogeneity in Caenorhabditis elegans-bacterial interactions

The nematode Caenorhabditis elegans is a model system for host-microbe and host-microbiome interactions. Many studies to date use batch digests rather than individual worm samples to quantify bacterial load in this organism. Here it is argued that the large inter-individual variability seen in bacterial colonization of the C. elegans intestine is informative, and that batch digest methods discard information that is important for accurate comparison across conditions. As describing the variation inherent to these samples requires large numbers of individuals, a convenient 96-well plate protocol for disruption and colony plating of individual worms is established.

Methods
Data are CFU/worm measurements for individual C. elegans. Raw data were CFU counts from spotting or spreading ten-fold serial dilutions on agar plates after mechanical disruption of worms in 200 uL buffer/worm to release bacteria. Data here were converted from raw counts as (counts)*(correction factor to 200 uL)*10^(dilution factor).