Limosilactobacillus reuteri, SUBSP. REUTERI, 2021

Li, Fuyong, Cheng, Christopher C., Zheng, Jinshui, Liu, Junhong, Quevedo, Rodrigo Margain, Li, Junjie, Roos, Stefan, Gänzle, Michael G. & Walter, Jens, 2021, Limosilactobacillus balticus sp. nov., Limosilactobacillus agrestis sp. nov., Limosilactobacillus albertensis sp. nov., Limosilactobacillus rudii sp. nov. and Limosilactobacillus fastidiosus sp. nov., five novel Limosilactobacillus species isolated from the vertebrate gastrointestinal tract, and proposal of six subspecies of Limosilactobacillus reuteri adapted to the gastrointestinal tract of specific vertebrate hosts, International Journal of Systematic and Evolutionary Microbiology (004644) 71 (2), pp. 1-21 : 17-18

DESCRIPTION OF LIMOSILACTOBACILLUS REUTERI SUBSP. REUTERI SUBSP. NOV.

Limosilactobacillus reuteri subsp. reuteri (reu′ te.ri. N.L. gen. n. reuteri , of Reuter; named for G. Reuter, a German bacteriologist after whom the species L. reuteri was named).

L. reuteri strains clustered in lineage II ( Fig. 3 ) belong to L. reuteri subsp. reuteri and they were isolated from humans and herbivores [ 7, 43]. Strains of this subspecies have ANI values of 98.1–100.0% with each other and ANI values of 94.0–96.5% with other L. reuteri strains belonging to different subspecies ( Fig. 4 ). Acid is produced from L-arabinose,D-ribose, D-galactose,D-glucose, maltose, lactose, melibiose, sucrose and raffinose; acid production from potassium gluconate is strain-specific; acid is not produced from D-xylose,D-fructose, D-mannose, methylα- D-glucopyranoside, aesculin, glycerol, erythritol, D-arabinose, L-xylose, D-adonitol, methyl β -Dxylopyranoside, L-sorbose, L-rhamnose, dulcitol, inositol, D-mannitol, D-sorbitol, methyl α- D-mannopyranoside, N -acetylglucosamine, amygdalin, arbutin, salicin, cellobiose, trehalose, inulin, melezitose, starch, glycogen, xylitol, gentiobiose, turanose, D-lyxose, D-tagatose, D-fucose, L-fucose, D-arabitol,L-arabitol, potassium 2-ketogluconate or potassium 5-ketogluconate. Phylogenetic analyses based on the core genes identified in this study ( Fig. 3 ) and previous studies [ 5, 43], AFLP and MLSA (using concatenated sequences of ddl, pkt, leuS, gyrB, dltA, rpoA and recA genes) [ 7], suggest that these strains are genetically homogeneous [ 8]. Strains of this subspecies possess the pdu-cbi-cob-hem cluster (pdu cluster) [ 6, 8], which equips them with the ability to utilize 1,2-propanediol and glycerol as electron acceptors [ 16, 39, 40] and to produce the antimicrobial compound reuterin [ 8]. They also produce histamine from histidine that has been linked to their anti-inflammatory phenotype [ 34]. Strains belonging to this subspecies have been considered as immunosuppressive because they could suppress the proinflammatory cytokines tumour necrosis factor (TNF), monocyte chemoattractant protein (MCP)-1, interleukin (IL)-1 β and IL-12, as well as suppress intestinal inflammation [ 34].

The type strain, DSM 20016 T (=ATCC 23272 T =F 275 T [original designation]), was isolated from the gastrointestinal tract of an adult human [ 6, 44, 45], with a DNA G+C content of 38.9mol%.

Figures

Fig. 3. A maximum-likelihood phylogenetic tree reconstructed using core genes (n=100) identified from whole-genome sequences, showing the evolutionary relationships among six L. reuteri subspecies.The tree was reconstructed using 33 L. reuteri genomes available in public databases (n=6 for L. reuteri subsp. kinnaridis, n=2 for L. reuteri subsp. porcinus, n=5 for L. reuteri subsp. murium, n=10 for L. reuteri subsp. reuteri, n=5 for L. reuteri subsp. suis and n=5 for L. reuteri subsp. rodentium) and L. balticus BG-AF3-AT was used as an outgroup. Further information on the involved genome sequences is listed in Table S1. The tree was inferred based on the GTR+G model with 1000 bootstrap replicates and only bootstrap values above 60% are shown. The tree was drawn with iTOL [54].

Fig. 4. Pairwise average nucleotide identity values (ANI; %) of genome sequences belonging to the same or different L. reuteri subspecies. ANI values within the same subspecies and between different subspecies were calculated for 33 L. reuteri genomes available in public databases (n=6 for L. reuteri subsp. kinnaridis, n=2 for L. reuteri subsp. porcinus, n=5 for L. reuteri subsp.murium, n=10for L. reuteri subsp.reuteri, n=5 for L. reuteri subsp. suis and n=5 for L. reuteri subsp. rodentium). Further information on the involved genome sequences is listed in Table S1.