Writing in Nature, the Finland-based team finds the microbiota changes caused by 2′-FL contribute to the production of short-chain fatty acids (SCFAs) with lower acetate and lactate production compared with lactose or GOS.
The DuPont Nutrition & Biosciences team also observe the fermentation of 2′-FL requires more specific microbial activity than lactose or GOS fermentation.
“Our previous in vitro cultivation experiments, as well as literature, indicated that 2’-FL is selectively utilised by only certain types of bifidobacteria and Bacteroides species, says DuPont scientist and study team member Krista Salli.
“This type of modelling with a complex microbiota is a step ahead in our journey to understand the prebiotic mechanisms of 2’-FL.”
The most abundant human milk oligosaccharides (HMOs) in breast milk, that is currently also available via large-scale commercial production, is 2′-fucosyllactose (2′-FL),
This HMO selectively promotes the growth of bifidobacteria, specifically Bifidobacterium longum ssp. infantis and Bifidobacterium bifidum, but also stimulates growth of some Bacteroides species.
HMOs also play a role in improving host defence as well as promoting intestinal barrier function with around 1% of ingested HMOs absorbed into the infant’s systemic circulation.
However, most of HMOs are metabolised by the gut microbiota or excreted intact in the faeces of infants.
Study materials and methods
Using the EnteroMIX colon simulator to model bacterial fermentation in the infant colon, the team began investigating the effect of 2′-FL on the infant microbiota and microbial metabolites.
DuPont’s Care4U, 2’-FL product, was evaluated in comparison to galacto-oligosaccharide (GOS), lactose and a control without the addition of a carbon source.
Data was then evaluated depending on faecal sample donor feeding type: breast-fed (BF) or formula-fed (FF), where the team was able to rate 2′-FL fermentation as either fast or slow.
The researchers found variations between the simulations in the ability to utilise 2′-FL, with the predominant phyla regulated by 2′-FL, GOS and lactose resulted in increases in Firmicutes and Actinobacteria numbers.
Additional findings pointed to a numerical decrease in Proteobacteria compared to control.
In fast-fermenting simulations, Actinobacteria increased with a noticeable trend for higher Bifidobacterium.
Short-chain fatty acids and lactic acid production using 2’FL as the energy source were formed to intermediate levels compared to the control, GOS or lactose.
Finally, in the 2′-FL fast-fermenting group, acetic acid levels increased with 2′-FL, whereas lactose and GOS utilisation also increased lactic acid production.
“While this study was done under simulated gut conditions, it showed the differences between the carbohydrates, especially in the production of microbial metabolites,” said Ratna Mukherjea, technical fellow and global R&D development Leader - HMO, DuPont Nutrition & Biosciences.
“These kind of study approaches can give more understanding on the how HMOs can be utilised by the microbiota with a method that is not invasive, which is important especially in the case of infants.”
In discussing the study’s findings and their significance, the team add that they did not expect that 2′-FL alone as a carbon source would be able to benefit the entire bifidobacterial community.
“Substantial selection occurred, indicating that 2′-FL alone promoted the growth of bacteria that can metabolize it and that the maintenance of the entire community structure requires a more complex mixture of HMOs,” they say.
However, further analysis finds all treatments increased total bifidobacterial number over the control simulation, which the team say is an indication of the bifidogenic effect observed for GOS and for 2′-FL.
Further analysis highlights the advantages of the Enteromix simulation model, particularly its ability to enable the study of metabolite production by complex microbial ecosystem.
The model also enables the study of colonic fermentation, which is difficult to study in vivo in human beings.
“This study exemplifies the utility of the DuPont Enteromix infant gut simulator to compare the fermentation of the carbohydrates between each other,” says DuPont’s senior scientist Heli Anglenius.
“Over the years, the Enteromix gut simulator has been used successfully for a multitude of studies with fecal microbiota sampled from adults.”
“This study demonstrates its applicability to studies where the microbiota is obtained from infants. This is a great continuation for more than 20 years of expertise using our own pre-clinical modelling.”
Published online: doi.org/10.1038/s41598-019-49497-z
“The effect of 2′-fucosyllactose on simulated infant gut microbiome and metabolites; a pilot study in comparison to GOS and lactose.”
Authors: Krista Salli et al.