Human Gut Microbes May Help Create Biofuels of the Future

Scientists are continuing to search for new materials to create biofuels to power vehicles and other machines. They've scoured cow rumens and termite guts for microbes that can efficiently break down plant cell walls. Now, though, scientists have taken a look at the human gut and have found that microbes there can digest fiber, breaking it down into simple sugars.

The researchers were first lead toward human gut microbes after their work in cows. More specifically, they found that cow microbes might be related to ones in the human gut.

"In looking for biofuels microbes in the cow run, we found that Prevotella bryantii, a bacterium that is known to efficient break down (the plant fiber) hemicellulose, gears up production of one gene more than others when it is digesting plant matter," said Isaac Cann, one of the researchers, in a news release.

The scientists searched a database for similar genes in other organisms and found them in microbes from the human gut. In the end, they wound up focusing on two human microbes: Bacteroides intestinalis and Bacteroides ovatus.

The researchers expressed the human cut bacterial enzymes and found that the human ones were actually more active in breaking down hemicellulose than the cow enzymes. When the scientists looked more closely at the structure of the human enzymes, they saw that many single polypeptide chains actually contained two enzymes, one of which was embedded in the other. After further analyzing the most important protein, the researchers found that the embedded component was a carbohydrate-binding molecule (CBM), which latches onto carbohydrates and shreds the plant fiber.

"In addition to finding microbes in the cow rumen and the termite gut, it looks like we can actually make some contributions ourselves," said Cann. "And our bugs seem to have some enzymes that are even better than those in the cow rumen."

The findings reveal that human microbes could potentially be a potent source for microbes that can help with biofuels production. That said, further research is needed before scientists begin to actually use these microbes.

The findings are published in the journal Proceedings of the National Academy of Sciences.