New insights into how gut bacteria break down sugars is published online this week in Nature Chemical Biology. These results could have implications in the human diet.

Bacteria need sugars as food to grow. Gut bacteria, also known as ‘symbiotic’ bacteria, obtain these sugars by breaking down larger chains of sugars ― or ‘complex’ sugars ― found in both human diet and human cells, a process which is critical for human health and digestion. However, the specific proteins that perform these tasks along the way have been elusive. In particular, a very common complex sugar contains four different types of chemical bonds, requiring four enzymes, known as glycoside hydrolases, to cut the pieces apart.

Harry Gilbert, Gideon Davies and colleagues profile 22 of the 23 glycoside hydrolases found in one of our gut bacteria. Unexpectedly, the researchers find a wide range of enzyme functions, explaining how this species can degrade these complicated sugar structures. These findings add to our growing understanding of our bacterial symbionts and the complexities of human digestion.