title: Detection of sialic acid-utilising bacteria in a caecal community batch culture using RNA-based stable isotope probing.
abstract: Sialic acids are monosaccharides typically found on cell surfaces and attached to soluble proteins, or as essential components of ganglioside structures that play a critical role in brain development and neural transmission. Human milk also contains sialic acid conjugated to oligosaccharides, glycolipids, and glycoproteins. These nutrients can reach the large bowel where they may be metabolised by the microbiota. However, little is known about the members of the microbiota involved in this function. To identify intestinal bacteria that utilise sialic acid within a complex intestinal community, we cultured the caecal microbiota from piglets in the presence of 13C-labelled sialic acid. Using RNA-based stable isotope probing, we identified bacteria that consumed 13C-sialic acid by fractionating total RNA in isopycnic buoyant density gradients followed by 16S rRNA gene analysis. Addition of sialic acid caused significant microbial community changes. A relative rise in Prevotella and Lactobacillus species was accompanied by a corresponding reduction in the genera Escherichia/Shigella, Ruminococcus and Eubacterium. Inspection of isotopically labelled RNA sequences suggests that the labelled sialic acid was consumed by a wide range of bacteria. However, species affiliated with the genus Prevotella were clearly identified as the most prolific users, as solely their RNA showed significantly higher relative shares among the most labelled RNA species. Given the relevance of sialic acid in nutrition, this study contributes to a better understanding of their microbial transformation in the intestinal tract with potential implications for human health.
authors: AgResearch Ltd, Food Nutrition & Health Team, Food & Bio-based Products Group, Grasslands Research Centre, Private Bag 11008, Palmerston North 4442, New Zealand. wayne.young@agresearch.co.nz.
authors: Wayne
authors: W
authors: Young
authors: Microbiology & Hygiene Group, Faculty of Medical and Life Sciences, Furtwangen University, 78054 Villingen-Schwenningen, Germany. Markus.Egert@hs-furtwangen.de.
authors: Markus
authors: M
authors: Egert
authors: AgResearch Ltd, Food Nutrition & Health Team, Food & Bio-based Products Group, Grasslands Research Centre, Private Bag 11008, Palmerston North 4442, New Zealand. shalome.bassett@agresearch.co.nz.
authors: Shalome A
authors: SA
authors: Bassett
authors: AgResearch Ltd, Food Nutrition & Health Team, Food & Bio-based Products Group, Grasslands Research Centre, Private Bag 11008, Palmerston North 4442, New Zealand. Rodrigo.Bibiloni@arlafoods.com.|Arla Strategic Innovation Centre, Roerdrumvej 2, 8220 Brabrand, Denmark. Rodrigo.Bibiloni@arlafoods.com.
authors: Rodrigo
authors: R
authors: Bibiloni
mesh_terms: D000818:Animals; D061249:Batch Cell Culture Techniques; D002432:Cecum / Q000378:metabolism / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000302:isolation & purification; D007553:Isotope Labeling; D007709:Klebsiella / Q000302:isolation & purification; D007778:Lactobacillus / Q000302:isolation & purification; D008297:Male; D064307:Microbiota; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012760:Shigella / Q000302:isolation & purification; D013552:Swine
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D019158:N-Acetylneuraminic Acid