The red emphasis is mine. I thought this was really interesting, especially that the ecology of the colon can change from centimeter to centimeter.
The article goes on to say:Scientists have known for decades that various microbes in the colon collaborate to ferment undigested food and degrade and dispose of the byproducts of fermentation. (M.P. Bryant, who was an animals sciences professor at Illinois, discovered the first hydrogen-based symbiotic relationship among microbes of the gut in the 1960s.)
Disruptions of the colonic ecosystem can have profound implications for human health, Greenberg said. Although there is a genetic component as well, evidence suggests that inflammatory bowel disease (which includes Crohn's disease and ulcerative colitis) emerges in response to a microbial imbalance, he said. A study led by Gaskins in 2006 demonstrated for the first time that hydrogen sulfide, a major byproduct of bacterial fermentation in the gut, is genotoxic (damaging to DNA) and may lead to colon cancer.
"We're getting closer and closer to looking at the microbiological origin of many diseases," Greenberg said.
The researchers found variation among individual study subjects, particularly in the abundance of the three classes of microbes at different biopsy sites. And the team made a surprising discovery when analyzing biopsies taken less than a centimeter apart: microbial diversity can occur even at this small scale.
"These data indicate that if you get down to the scale at which these microbes make their living, perhaps it's not all the same," Gaskins said. "We haven't begun yet to think at that spatial scale."
The finding is relevant because disease tends to originate in very specific regions of the colon, Greenberg said. Ulcerative colitis starts at the rectum and then proceeds "upriver," he said. "When you see Crohn's disease you see an area of involvement, then it's normal and then you see another area of involvement. And if you do surgery and remove the disease, the disease almost always recurs from the point of removal because -- we believe -- it's been reseeded with microbes."
Future studies will examine the role of hydrogenotrophic microbes in constipation and will look at how diet affects the composition and abundance of microbes in the colon, the researchers said.
