- Friday, January 30, 2009
- Lactobacillus suntoryeus Cachat and Priest 2005 is a later synonym of Lactobacillus helveticus (Orla-Jensen 1919) Bergey et al. 1925 (Approved Lists 1980)
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Sabri M. Naser, Karen E. Hagen, Marc Vancanneyt, Ilse Cleenwerck , Jean Swingsand Thomas A. Tompkins
Strain R0052, originating from a North American dairy starter culture, was initially identified as Lactobacillus acidophilus based on phenotypic analyses. However, upon sequencing the 16S rRNA gene, it became clear that the isolate was very highly related to Lactobacillus suntoryeus, Lactobacillus helveticus and Lactobacillus gallinarum, as similarities ranging from 99.3 to 99.8 % were observed. As an initial screening test to investigate the relatedness between strain R0052 and reference strains of L. suntoryeus, L. helveticus and L. gallinarum, the partial sequences for the genes encoding the alpha subunit of ATP synthase (atpA), RNA polymerase alpha subunit (rpoA), phenylalanyl-tRNA synthase alpha subunit (pheS), the translational elongation factor Tu (tuf), a surface-layer protein (slp), the Hsp60 chaperonins (groEL) were determined and revealed high relatedness between all strains. Determination of the sequence of the 16S–23S rDNA internally transcribed spacer (ITS) revealed 98.3 to 100 % identity among L. suntoryeus and L. helveticus strains. SDS-PAGE of whole-cell proteins did not distinguish both species. Fluorescent Amplified Fragment Length Polymorphism (FAFLP) could distinguish both taxa, but still constituted a single cluster within L. acidophilus group. Finally DNA-DNA hybridization experiments between the new isolate and the reference strains of L. helveticus and L. suntoryeus yielded binding values above 70 % and confirmed that both species are synonymous taxa.