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Key Gut Bacteria Hungry for Green Vegetables

SULFOSUGARS from green vegetables promote important gut bacteria in humans, research from Vienna has found. The team from the Center for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria, analysed how the gut microbes processed the plant-based, sulfur-containing sugar sulfoquinovose, a sulfonic acid derivative of glucose, which is found in greens such as lettuce, spinach, and algae; they discovered that a group of specialised gut bacteria co-operated in the utilisation of the sulfosugars to produce hydrogen sulfide.  

Advancements in sequencing and analytical techniques in the last two decades have facilitated extensive insights into the significant role microorganisms play in human health. However, the metabolic capabilities of the microbiota (what substances they feed on and how they process them) is still largely unknown; this new insight into the metabolism of sulfosugar sulfoquinovose is the first to shed light on this topic. 

The research team in Vienna worked with researchers from the University of Konstanz, Konstanz, Germany, to analyse stool samples to determine what microbial processes were occurring. We have now been able to show that, unlike glucose, for example, which feeds a large number of microorganisms in the gut, sulfoquinovose stimulates the growth of very specific key organisms in the gut microbiome,” says David Schleheck, Professor of Microbiology at the University of Konstanz. The Eubacterium rectale bacteria ferment sulfoquinovose via a metabolic pathway… producing…a sulfur compound, dihydroxypropane sulfonate, which in turn serves as an energy source for other intestinal bacteria such as Bilophila wadsworthiaB. wadsworthia ultimately produces hydrogen sulfide from dihydroxypropane sulfonate via a metabolic pathway that was also only recently discovered,” explained Prof Schleheck. 

As well as being produced by specialised microorganisms, hydrogen sulfide is also produced by the body cells, and can have both a positive and a negative effect on human health. In low amounts, the gas has anti-inflammatory effects on the intestinal mucosa; increased production by gut microbes, however, which has been linked to diets rich in meat or fat, is associated with chronic inflammatory diseases and cancer. 

Further collaborative research from the two teams will focus on clarifying whether and how plant-based sulfosugars can have a health-promoting effect and whether sulfoquinovose could be used as a prebiotic. These results also contribute to the necessary knowledge to potentially therapeutically target interactions between the microbiome and nutrition in the future.