In Vitro Infant Faecal Fermentation of Low Viscosity Barley β-Glucan and Its Acid Hydrolyzed Derivatives: Evaluation of Their Potential as Novel Prebiotics

Abstract

Barley contains high level of β-1,3-1,4-glucans (BBGs) which can be fermented by microbes and are a potential prebiotic. In the present study, native BBG with low viscosity and a MW of 319 kDa was depolymerized by acid hydrolysis to produce a series of four structurally characterized fragments with MWs ranging from 6–104 kDa. In vitro fermentation of these BBG samples by infant faecal microbiome was evaluated using a validated deep-well plate protocol as parallel miniature bioreactors. Microbial taxa were identified using 16S amplicon sequencing after 40 h of anaerobic fermentation. Bioinformatics analysis including diversity indexes, predicted metagenomic KEGG functions and predicted phenotypes were performed on the sequenced data. Short chain fatty acids and dissolved ammonia were quantified and the SCFAs/NH3 ratio was used to evaluate the eubiosis/dysbiosis potential. Correlation analysis showed that most of the parameters investigated showed a parabolic function instead of a monotonous function with the BBG samples having different MWs. Among the five BBGs, it was concluded that BBG with an intermediate MW of 28 kDa is the most promising candidate to be developed as a novel prebiotic.

Endo-1,3(4)-β-Glucanase-Treatment of Oat β-Glucan Enhances Fermentability by Infant Fecal Microbiota, Stimulates Dectin-1 Activation and Attenuates Inflammatory Responses in Immature Dendritic Cells

“…In contrast to native oat β-glucan that was not fermented by infant fecal microbiota, endo-1,3(4)-β-glucanase-treated oat β-glucan was degraded by the fecal microbiota of both 2- and 8-week old infants. This result corroborates the findings of Lam et al [ 19 ], who observed an increase in SCFA production when lowering the molecular weight of barley β-glucans in an in vitro fermentation study using infant fecal inocula. We also found that decreasing the size of oat β-glucans by enzyme treatment resulted in a stronger stimulation of Enterococcus and increased production of lactic acid, which were more pronounced in the fecal inoculum of 2-week-old infants.…”

“…As enterococci are known to be among the first colonizers of the infant gut [ 43 ], the increase in enterococci might be relevant in infants for creating a new environment that allows colonization of the gut by strict anaerobes [ 2 , 20 ]. A similar stimulation of Enterococcus was shown in an in vitro fermentation study of barley β-glucans using the fecal microbiota of 9–15-month old infants which received both human milk and solid foods [ 19 ]. With these age groups, substantial production of SCFAs was also observed, which indicates that the fecal microbiota of 9–15-month-old infants are capable of degrading native oat β-glucan.…”

“…Non-digestible carbohydrates are often added to cow milk-based infant formula to substitute HMO functions. Commonly used NDCs are FOS and GOS; however, β-glucans might also have potential as possible addition to infant formula, as these molecules also stimulate the growth of beneficial microbes [ 18 , 19 ] and have immune modulating effects [ 15 , 16 ]. However, at present, only limited knowledge is available about the effects of fermentation of oat β-glucans on their immune-modulating properties.…”

“…Enzymatic pretreatment of barley β-glucans enhanced their fermentability by adult fecal microbiota in an in vitro setup [ 18 ]. Depolymerization of barley β-glucans by acid hydrolysis into fractions with MWs ranging from 6–104 kDa has also been shown to increase glucan fermentability with the inoculum of 9–15 month-old infants [ 19 ]. However, currently, only limited knowledge is available about the effects of fermentation of β-glucans on their immune-modulating properties, and whether an increase in fermentability, due to depolymerization, affects these processes.…”

EFFECT OF Pleurotus ostreatus AQUEOUS EXTRACT ON PHYSICOCHEMICAL PROPERTIES, PROTEIN PROFILE AND TOTAL LACTIC ACID BACTERIA OF YOGURT FORTIFIED WITH Lactobacillus acidophilus

“…Yogurt added with 3% POAE had the highest total acid content (P<0.05). POAE could be utilized by LAB as additional carbon source as POAE contains β-glucan, a water-soluble dietary fiber and a prebiotic (Sari et al, 2017;Lam et al, 2019). This could increase the production of acid by LAB, thus the total acid content of yogurt added with 3% POAE was higher than the others.…”