Water treatment focuses on how to get rid of bad bacteria from poop, but most of the time, the organisms are studied in isolation. But that’s not how bacteria work. When there is one bacteria, there are a lot of bacteria. You need to study how a giant colony of them affects the body. What would help would be a mechanical colon that can simulate conditions inside the human body to help better understand how bacteria act in their communities, which include other microorganisms like archaea, fungi, and protozoa.
And that’s exactly what Ian Marcus and his advisor have done, creating a system that replicates a human colon, septic tank, and groundwater—a system that needed feeding three times a day during week-long experiments to simulate human eating.
"The idea sprung from previous experiments that show that bacteria change in their characteristics depending on the way they’re grown," Ian Marcus, a newly minted PhD student from the University of California at Riverside told Co.Exist. "So we wanted to make as real a system as possible to understand how the environment influences the behavior of the bacteria."
Marcus spent a year constructing the device, which looks like a big tube connected to a septic system. He kept it on a regular feeding schedule so the bacterial communities could work their magic, breaking down food and creating smelly output. Making food for the hungry machine is no easy task. Marcus says it takes about an hour and a half to mix the 20 or so ingredients—proteins, carbs, vitamins, fats—that go into a western diet. Fortunately, one batch lasts for a whole week.
He studied how a particularly nasty strain of E. coli worked through the gut and into the septic system, two places researchers have studied in the past, but the studies had never been linked. Marcus says he found some surprising results: when E. coli passed from the colon to septic tank, the bacteria changed the way it moved.
"When it’s in this community, it will not transport as far, but it lasts a lot longer in the environment," he says. In addition, the E. coli had a higher possibility to be part of a biofilm, which can last a long time as it moves down the length of the pipes—and from there the pathogen can creep into groundwater. Marcus adds that with new rainfall, the bacteria can reach new areas.
The human colon and septic system is also being used to test how nanoparticles—now used as a coating in socks, in sunscreens and even in cereals with little regulation—move through the water system. "Whereas there is a protocol for how to deal with bacteria like E. coli, right now, there are no regulations against nanoparticles, and we’re testing how they affect microbial communities and the environment," he says.
Looking at one element in isolation just won’t cut it when it comes to the future of biology. Says Marcus: "We now have the tools to look at the whole community to understand what is going on at a systems level—we have got to change the way we study these things if we want to understand the real world."