The Effect of Hydrolyzed and Fermented Arabinoxylan-Oligo Saccharides (AXOS) Intake on the Middle-Term Gut Microbiome Modulation and Its Metabolic Answer

Abstract

Although fermentation and hydrolyzation are well-known processes to improve the bioavailability of nutrients and enable the fortification with dietary fibers, the effect of such pre-treatments on the prebiotic features of arabinoxylan-oligosaccharides (AXOS) had not been explored. The middle-term in vitro simulation through the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) demonstrated that the feeding with different formulations (namely oat bran, rye bran and wheat bran) containing hydrolyzed AXOS fermented by lactic acid bacteria significantly increased the synthesis of short-chain fatty acids (SCFA) by colon microbiota, with hydrolyzed and fermented rye bran displaying the highest effect. After two weeks from the interruption of intake, SCFA concentrations significantly decreased but remained still significantly higher compared to the original condition. The microbiome was also affected, with a significant abundance increase in Lactobacillaceae taxon after feeding with all fermented and hydrolyzed formulates. Hydrolyzed and fermented rye bran showed the highest changes. The fungal community, even if it had a lower variety compared to bacteria, was also modulated after feeding with AXOS formulations, with an increase in Candida relative abundance and a decrease in Issatchenkia. On the contrary, the intake of non-hydrolyzed and non-fermented wheat bran did not produce relevant changes of relative abundances. After two weeks from intake interruption (wash out period) such changes were mitigated, and the gut microbiome modulated again to a final structure that was more like the original condition. This finding suggests that hydrolyzed AXOS fermented by lactic acid bacteria could have a more powerful prebiotic effect compared to non-hydrolyzed and non-fermented wheat bran, shaping the colon microbiome and its metabolic answer. However, the intake should be continuous to assure persistent effects. Opening a window into the ecological evolutions and plausible underlying mechanisms, the findings reinforce the perspective to explore more in depth the use of hydrolyzed and fermented AXOS as additional ingredient for bread fortification.

Impact of isolated and chemically modified dietary fiber on bakery products: Current knowledge and future directions

“…However, the lower M w and soluble AX concentration in many samples may have hindered the bifidogenic effect, emphasizing the importance of the concentration and molecular characteristics of the solubilized fiber for achieving desired prebiotic properties (Lynch et al, 2021). These findings are in contrast with those of Polo et al (2023), who found that hydrolyzed AXOS may show a stronger prebiotic effect when compared to nonhydrolyzed and nonfermented variants. In conclusion, although clinical studies on human responses to AX‐enriched products are limited, the existing studies have shown promising results.…”

“…To support this, EFSA has established a health claim for the consumption of AX and recommends an intake of 8 g of AX-rich fiber from wheat endosperm (Kellow & Walker, 2018). However, clinical studies with AX-enriched products are still (Lynch et al, 2021;Polo et al, 2023). However, the lower M w and soluble AX concentration in many samples may have hindered the bifidogenic effect, emphasizing the importance of the concentration and molecular characteristics of the solubilized fiber for achieving desired prebiotic properties (Lynch et al, 2021).…”

“…In addition, to support the microbial shifts, Lynch et al (2021) analyzed different AXs derived from brewers' spent grain in a fecal microbiota model. The consumption of AX likely led to increased levels of Lactobacillus and a significant increase in Bifidobacterium , resulting in positive health outcomes (Lynch et al, 2021; Polo et al, 2023). However, the lower M w and soluble AX concentration in many samples may have hindered the bifidogenic effect, emphasizing the importance of the concentration and molecular characteristics of the solubilized fiber for achieving desired prebiotic properties (Lynch et al, 2021).…”

Inline and continuous gas monitoring in gastrointestinal tract models with carbon nanotube-based chemiresistive sensors

“…The SHIME ® model can be modified according to the specific digestive process of interest, thanks to the flexibility of its modular setup 15 . For our experiment, we developed a middle-term SHIME ® screening experiment composed of two bioreactors, the first reactor (R1) representing the stomach (ST) and the small intestine (SI), and the second reactor (R2) modelling the proximal colon (PC) 8 . To collect the waste, a container connected to the R2 was located beneath the supporting table.…”

“…5a shows the gas profile of the SHIME ® sample measured through Quadrupole MS. Several peaks emerge from the graph compared to the background sample (N 2 ). In particular, water vapor (8,16,17,18 (20,36,38,40 m/z) peaks are probably due to the presence of ambient air in the sample bag. Gases are experiment-specific, which means that the gas species and concentrations reported in a specific scientific work are related to the specific food, treatment, or faecal donor used in the study.…”