Our knowledge about the gut microbiota of pigs is still scarce, despite the importance of these animals for biomedical research and agriculture. Here, we present a collection of cultured bacteria from the pig gut, including 110 species across 40 families and nine phyla. We provide taxonomic descriptions for 22 novel species and 16 genera. Meta-analysis of 16S rRNA amplicon sequence data and metagenome-assembled genomes reveal prevalent and pig-specific species within Lactobacillus, Streptococcus, Clostridium, Desulfovibrio, Enterococcus, Fusobacterium, and several new genera described in this study. Potentially interesting functions discovered in these organisms include a fucosyltransferase encoded in the genome of the novel species Clostridium porci, and prevalent gene clusters for biosynthesis of sactipeptide-like peptides. Many strains deconjugate primary bile acids in in vitro assays, and a Clostridium scindens strain produces secondary bile acids via dehydroxylation. In addition, cells of the novel species Bullifex porci are coccoidal or spherical under the culture conditions tested, in contrast with the usual helical shape of other members of the family Spirochaetaceae. The strain collection, called ‘Pig intestinal bacterial collection’ (PiBAC), is publicly available at www.dsmz.de/pibac and opens new avenues for functional studies of the pig gut microbiota.
Repeats of the disaccharide unit N-acetyllactosamine (LacNAc) occur as type 1 (Galβ1, 3GlcNAc) and type 2 (Galβ1, 4GlcNAc) glycosylation motifs on glycoproteins and glycolipids. The LacNAc motif acts as binding ligand for lectins and is involved in many biological recognition events. To the best of our knowledge, we present, for the first time, the synthesis of LacNAc type 1 oligomers using recombinant β1,3-galactosyltransferase from Escherichia coli and β1,3-N-acetylglucosaminyltranferase from Helicobacter pylori. Tetrasaccharide glycans presenting LacNAc type 1 repeats or LacNAc type 1 at the reducing or non-reducing end, respectively, were conjugated to bovine serum albumin as a protein scaffold by squarate linker chemistry. The resulting multivalent LacNAc type 1 presenting neo-glycoproteins were further studied for specific binding of the tumor-associated human galectin 3 (Gal-3) and its truncated counterpart Gal-3∆ in an enzyme-linked lectin assay (ELLA). We observed a significantly increased affinity of Gal-3∆ towards the multivalent neo-glycoprotein presenting LacNAc type 1 repeating units. This is the first evidence for differences in glycan selectivity of Gal-3∆ and Gal-3 and may be further utilized for tracing Gal-3∆ during tumor progression and therapy.
The availability of nucleotide sugars is considered as bottleneck for Leloir‐glycosyltransferases mediated glycan synthesis. A breakthrough for the synthesis of nucleotide sugars is the development of salvage pathway like enzyme cascades with high product yields from affordable monosaccharide substrates. In this regard, the authors aim at high enzyme productivities of these cascades by a repetitive batch approach. The authors report here for the first time that the exceptional high enzyme cascade stability facilitates the synthesis of Uridine‐5′‐diphospho‐α‐d‐galactose (UDP‐Gal), Uridine‐5′‐diphospho‐N‐acetylglucosamine (UDP‐GlcNAc), and Uridine‐5′‐diphospho‐N‐acetylgalactosamine (UDP‐GalNAc) in a multi‐gram scale by repetitive batch mode. The authors obtained 12.8 g UDP‐Gal through a high mass based total turnover number (TTNmass) of 494 [gproduct/genzyme] and space‐time‐yield (STY) of 10.7 [g/L*h]. Synthesis of UDP‐GlcNAc in repetitive batch mode gave 11.9 g product with a TTNmass of 522 [gproduct/genzyme] and a STY of 9.9 [g/L*h]. Furthermore, the scale‐up to a 200 mL scale using a pressure operated concentrator was demonstrated for a UDP‐GalNAc producing enzyme cascade resulting in an exceptional high STY of 19.4 [g/L*h] and 23.3 g product. In conclusion, the authors demonstrate that repetitive batch mode is a versatile strategy for the multi‐gram scale synthesis of nucleotide sugars by stable enzyme cascades.
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