CH391L/S12/Bacterial Odor Engineering

Bacterial communities are capable of producing a wide variety of odor molecules. At its most basic, an odorant is simply a volatile chemical compound that triggers an olfactory response. These compounds fall into many categories, and a few examples will be discussed here. These compounds can be produced for a variety of reasons, from simple metabolic byproducts to targeted cellular messengers. Although bacteria don't have an olfactory system in the same sense as higher organisms, there is evidence that bacterial communities can communicate via volatile airborne compounds and that they may be an important bacterial defense sensor.

Natural Bacterial Odorant Production

It's difficult not to view bacterial odorant production through a human lens, but it's important to remember that the particular descriptions of these compounds are purely coincidental when it comes to smell. When it comes to odorants produced naturally by bacterial populations, it's much more appropriate to view the compounds as products of synthetic pathways and not clouding them with human "uses" or "what they remind us of". That being said, naturally occurring bacterial odorants have been used by humans and other organisms for very interesting ends.

Carnivorous mammals including dogs, wolves and hyenas possess potent scent glands near their anus called apocrine glands. These sacs produce a thick liquid or paste that the animals use to mark territory and identify each other. This is why you see dogs sniffing near each other's anuses when meeting each other. Human and primate apocrine glands migrated upwards to our chest and armpit regions as we began to walk upright, and today they remain the source of our armpit odors. The glands produce a mostly odorless liquid, which is in turn metabolized by hundreds of species of skin-dwelling bacteria, with high densities of Corynebacteria.