The compound, which is found in the cell walls of cranberries, was found to help growth of specific strain of Bifidobacterium longum, according to the study in Applied and Environmental Microbiology.
Scientists discovered that the sub-species of Bifidobacteria multiplied when fed with indigestible plant sugars called xyloglucans.
“This is the first evidence that certain strains of bifidobacteria consume xyloglucans,” according to David Sela, study leader and nutritional microbiologist at University of Massachusetts Amherst.
“This is significant as bifidobacteria interact with this dietary compound [xyloglucan] to potentially impact human host health through energy and metabolite production,” wrote lead author Ezgi Özcan.
Bifidobacteria form part of the human gut microbiome and are recognised as beneficial to health. Although present in adults, bifidobacteria are most abundant in newborn, breast-fed babies.
Prebiotics are currently in focus due to their ability to promote beneficial gut bacteria growth and potentially. The indigestible carbohydrates are often found in the cell walls of plants and include plant sugars such as xyloglucans.
"A lot of plant cell walls are indigestible," Sela explains, "and indeed we cannot digest the special sugars found in cranberry cell walls called xyloglucans. But when we eat cranberries, the xyloglucans make their way into our intestines where beneficial bacteria can break them down into useful molecules and compounds."
The scientists prepared a highly purified form of xyloglucans derived from cranberries with assistance from Ocean Spray Inc., who partially funded the study.
When they fed xyloglucans to Bifidobacterium longum under anaerobic laboratory conditions, researchers found only certain bacteria strains consumed them. This is significant because individual variations in human microbiome content may mean some infants and adults may be more able to use xyloglucans than others.
The bacteria strains that fed on xyloglucan did so by a non-typical metabolism. The bacteria produced different proportions of short-chain fatty acids (additional formate and acetate but less lactate), than when fed simple sugars.
Additionally, the scientists discovered that cross-feeding between bacteria occurred. The process (known as syntrophic interaction) is where “one strain degrades the xyloglucan to make it available to a second strain,” the authors explain.
Similar instances of cross feeding are thought to occur within the gut. However, the impacts of altered metabolism and cross feeding on the overall microbiome and host health is not clear.
Nevertheless, the authors conclude that the study findings “may lead to novel foods or supplements to impact human health through rational manipulations of their microbiome”.
In particular, the interactions between species of Lactobacillus, Bifidobacterium and prebiotic oligosaccharides may be of use in developing future synbiotic products.
Source: Applied and Environmental Microbiology
Published online ahead of print, doi: 10.1128/AEM.01097-17
“A human gut commensal ferments cranberry carbohydrates to produce formate”
Authors: Ezgi Özcan, Jiadong Sun, David C. Rowley, and David A. Sela