Biochemical Basis of Xylooligosaccharide Utilisation by Gut Bacteria

Abstract

Xylan is one of the major structural components of the plant cell wall. Xylan present in the human diet reaches the large intestine undigested and becomes a substrate to species of the gut microbiota. Here, we characterised the capacity of Limosilactobacillus reuteri and Blautia producta strains to utilise xylan derivatives. We showed that L. reuteri ATCC 53608 and B. producta ATCC 27340 produced β-D-xylosidases, enabling growth on xylooligosaccharide (XOS). The recombinant enzymes were highly active on artificial (p-nitrophenyl β-D-xylopyranoside) and natural (xylobiose, xylotriose, and xylotetraose) substrates, and showed transxylosylation activity and tolerance to xylose inhibition. The enzymes belong to glycoside hydrolase family 120 with Asp as nucleophile and Glu as proton donor, as shown by homology modelling and confirmed by site-directed mutagenesis. In silico analysis revealed that these enzymes were part of a gene cluster in L. reuteri but not in Blautia strains, and quantitative proteomics identified other enzymes and transporters involved in B. producta XOS utilisation. Based on these findings, we proposed a model for an XOS metabolism pathway in L. reuteri and B. producta strains. Together with phylogenetic analyses, the data also revealed the extended xylanolytic potential of the gut microbiota.

Utilization of dietary mixed-linkage β-glucans by the Firmicute Blautia producta

“…The released amount of p -nitrophenol was determined by measuring the absorbance at 410 nm using NUNC 96 well plates on the SpectraMax i3x multi-mode microplate reader. The concentration of released p -nitrophenol was calculated accordingly to Beer Lambert law (A = εcl, where ε is the molar extinction coefficient of p -nitrophenol at 410 nm, c is the concentration and l is the optical path length in cm) as reported previously ( 83 ).…”

“…This article contains supporting information ( 1 , 3 , 38 , 39 , 40 , 48 , 55 , 83 , 85 , 87 , 88 , 89 , 90 , 91 , 92 , 93 ).…”

Effect of xylo-oligosaccharide on in vitro proliferation of lactic acid bacteria from rabbits

“…Therefore, it is crucial to identify responders and nonresponders of XOS for lactic acid bacteria strains resident in animals' gut [18,19] . To date, a few LAB strains such as Pediococcus acidilactici BCC-1, Limosilactobacillus reuteri ATCC 100-23C and L. reuteri ATCC 53608 isolated from the gut of broiler, mice, and pigs, respectively have been found to be able to markedly proliferate through e ciently utilizing XOS in vitro [20,21] . However, the interaction between XOS and resident microbes of rabbit' gut is still largely unknown.…”