![\"Prof.](\"https:\/\/blogs.ncl.ac.uk\/icamblog\/LisPaper-Harry.jpg\")
<\/a>Prof. Harry Gilbert<\/p><\/div>\n
The diverse organisms that live in our gut, collectively termed the gut microbiota<\/a>, can have a major impact on our health. A new paper<\/a> from Prof. Harry Gilbert\u2019s <\/a>lab in ICaMB, published today in Nature<\/a>, shows that one member of our gut microflora uses a \u2019selfish\u2019 mechanism to degrade a component of the cell wall of the yeast in our diet.<\/em><\/p>\n By\u00a0Drs. Elisabeth Lowe<\/a> and Fiona Cuskin<\/a>.<\/em><\/p>\n Have you over-indulged this Christmas? One too many ales, or too many turkey sandwiches?<\/p>\n Beer: full of yeast.<\/p><\/div>\n The good news is that, while your waist line may be expanding and you may be feeling a little the worse for wear, the organisms of your gut microbiota are thriving!<\/p>\n Some of the bacteria in the human gut, called Bacteroides<\/i>, can break down the complex carbohydrates<\/a> in our diet into simple sugars, which they use for energy.<\/p>\n <\/p>\n Our work, published in Nature today<\/a>, shows that\u00a0one of these bacteria can also break down some of the carbohydrate cell wall of yeasts, called mannan<\/a>, a polymer of mannose<\/a>. This includes mannan from Saccharomyces cerevisiae<\/i> <\/a>(Baker\u2019s yeast), and the pathogenic gut fungus, Candida albicans<\/i><\/a>. The current understanding of polysaccharide digestion by gut bacteria suggests a cooperative environment, in which break-down products are shared between different members of the microbiota. However\u00a0our data shows that this species (Bacteroides thetaiotaomicron<\/i><\/a>) is \u2018selfish\u2019 when it degrades mannan, and doesn\u2019t share any of the digestion products with other bacteria.<\/p>\n Turkey: er… full of yeast?<\/p><\/div>\n To achieve this selfish degradation, the large\u00a0and multiply-branched mannan structure undergoes only very limited degradation in the extracellular space (see figure). The resulting\u00a0processed mannan fragments\u00a0are then imported into the Bacteroides <\/em>periplasmic space<\/a>, where they are further degraded by a suite of glycoside hydrolase<\/a> enzymes to yield the sugar mannose. Achieving complete\u00a0breakdown within the periplasm prevents\u00a0 the mannose from being shared with competing bacteria.<\/p>\n This selfish approach to mannan utilisation could offer the opportunity to design bespoke prebiotics<\/a> targeted to a specific bacterial population within the gut. Food products containing yeast mannan would be expected to promote growth of B. thetaiotamicron<\/em>, whereas other complex polysaccharides may specifically\u00a0promote other members of the microbiota.<\/p>\n Complex polysaccharide mannan is sequentially degraded by a ‘selfish’ mechanism to yield periplasmic mannose.<\/p><\/div>\n A number of inflammatory bowel diseases such as Crohn\u2019s disease <\/a>are associated with intolerance to yeast, and particularly cell wall polysaccharides, and have also been linked to low levels of Bacteroides<\/i> species in the gut. Our work provides a potential mechanism for how Bacteroides<\/i> might be able to influence the effect of yeast on patients with Crohn\u2019s disease, and in fact a drug named Thetanix<\/a> (which is a live formulation of Bacteroides thetaiotaomicron<\/i>) has been licensed for treatment of paediatric Crohn\u2019s disease in the USA.<\/p>\n Researchers Max Temple, Lis Lowe and Fiona Cuskin of the Gilbert lab.<\/p><\/div>\n Yeast is commonly in our diet in the form of some of our favourite things: bread, beer, wine and fermented food products.\u00a0 So it may be dry January <\/a>but if your willpower fails and you succumb to an alcoholic beverage, then make sure it\u2019s an unfiltered one with plenty of yeast!<\/p>\n This research in the Gilbert lab was funded by the Wellcome Trust and the European Research Council.<\/em><\/p>\n Links:<\/p>\n Nature article: http:\/\/www.nature.com\/nature\/journal\/v517\/n7533\/full\/nature13995.html<\/a><\/p>\n Press release: http:\/\/www.ncl.ac.uk\/press.office\/press.release\/item\/beer-and-bread-yeast-eating-bacteria-aid-human-health<\/a><\/p>\n Gilbert Lab: http:\/\/www.ncl.ac.uk\/camb\/staff\/profile\/harry.gilbert<\/a><\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" The diverse organisms that live in our gut, collectively termed the gut microbiota, can have a major impact on our health. A new paper from Prof. Harry Gilbert\u2019s lab in ICaMB, published today in Nature, shows that one member … Continue reading <\/a>\n
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