Niche bacteria with a profound effect on your diet

Scientists working at Diamond Light Source have revealed that the digestion of highly abundant sources of dietary fibre may be mediated by niche species of bacteria within the distal gut.

The researchers were able to demonstrate that the genetic markers of such bacteria were limited to a small number of strains.

These bacteria are essential to break down the complex sugars found in fruit and vegetables common in the human diet. The findings will have immediate implications for the control of such bacteria by varying diet and nutrition.

A well balanced diet includes complex carbohydrate molecules known as polysaccharides. These are complex sugars commonly found in the cell walls of fruit and vegetables.

Our ability to digest these complex molecules relies on the massive community of microbes and bacteria that are resident within the distal gut. With many products purporting to assist these communities, scientists are working hard to understand their precise nature.

Image: Structure of Bacteroides ovatus GH5, the vanguard enzyme responsible for the initial break down of xyloglucan by these bacteria in our gut.

The researchers, from the Royal Institute of Technology (KTH), Sweden, University of Michigan Medical School, USA, University of York, and University of British Columbia, Canada, performed X-ray crystallography measurements using the I03 beamline.

The initial study relates to the enzymes that perform the ‘first chop’ of the polysaccharide. The next steps will be to investigate the enzymes further down the chain.

“For me, the next most important enzyme is GH31” continues Glyn Hemsworth, “if this isn’t present we can’t access the glucose – the fundamental fuel we’re after in our diet”.

The researchers will continue to investigate the systems and bacteria within the gut to find out the effects they have on human health, all in the hope that diets can soon be tailored to benefit these niche communities living within our bodies.

To find out more about using the I03 beamline, or to discuss potential applications, please contact Katherine McAuley: katherine.mcauley@diamond.ac.uk

Larsbrink J., Rogers T, E., Hemsworth G. R., McKee, L. S., Tauzin A. S., Spadiut O., Klinter S., Pudlo N. A., Urs K., Koropatkin N. M., Creagh L. A., Haynes C. A., Kelly A. G., Cederholm S. N., Davies G. J., Martens E. C. and Brumer H. A discrete genetic locus confers xyloglucan metabolism in select human gut Bacteroidetes. Nature 12907 (2014) DOI: 10.1038/nature12907