The average human body contains 2 to 5 pounds of bacteria. And if your first thought is “that’s an awful lot of perfectly good protein going to waste,” you’ll be relieved to hear that a large class of bacteria-eating viruses—called bacteriophages—agree with you, and a vast number of them (all but a few unknown to science) are chowing down on your body’s crunchy, delicious bacterial flora as we speak. As Forbes’ J.V. Chamary explains:
[T]he first phase of the Human Microbiome Project catalogued the microbes at five sites – mouth, nose, skin, urogenital and gastrointestinal tracts – in 242 American adults. As well as revealing the secrets of known species, information in the depths of metagenomes can also be mined to uncover microbes that we never knew we had, such as a newly-discovered virus called crAssphage.
One of the most interesting things about crAssphage—and yes, it’s actually called crAssphage—is the fact that it has gone so long without being discovered, which points to the existence of a secret ecosystem of viral bacteriophages that live in our guts. I realize that saying viruses “live" is kind of a controversial idea, so if you prefer to think of viruses as zombies or golems or whatever, substitute your verb of choice here.
In any case, whatever it is viruses do, they’re doing it inside of you—feasting on a massive universe of bacterial goodies—and it is likely that the vast majority of viruses in your personal bacterial wilderness are completely new types of critters that have never been seen by human eyes. The Human Microbiome Project will discover more, many more.
And this isn’t just the world’s tiniest, grossest birdwatching expedition; bacteriophages can actually save your life. Scientists have recently discovered that bacteriophages will ravenously munch on the deadly antibiotic-resistance superbacteria clostridium difficile (C. diff), given the opportunity. Since C. diff has been spreading in hospitals in recent years, and we don’t have any other tools to fight it with, that’s wonderful news for us—and perhaps even better news for the hungry bacteriophages who are turned loose on it.