A recent paper by Newton et al compares the microbial community composition in human stool to that of the sewage sludge that it inevitably ends up in. And surprise! The communities looked really similar. Sewage species recaptured most of the human stool species, and was essentially a medley of various gut microbes.
The really cool part is how the authors pitched the application of this information. For a long time now, researchers and doctors have been trying to find a way to diagnose a patient’s health using their gut microbiota. But this is an arduous and expensive task, and is made somewhat impossible by the sheer diversity between individual gut microbiota. Sewage provides something like an average of a city’s gut. This “average” can then be used to examine health trends among members of the community. The study found that percent obesity in the city explained a small but significant part of community variation. Although a loose association, this shows promise in using sewage to approximate the gut microbiota health of a specific population.
Hurrah for stool and sewage!