Summary auto-generated
This study re-evaluates the taxonomic classification of Lactobacillus curvatus subsp. melibiosus using polyphasic taxonomy methods. The original 1996 classification separated L. curvatus into two subspecies based on melibiose fermentation ability, with melibiose-positive strains designated as L. curvatus subsp. melibiosus. However, multiple subsequent studies reported conflicting results regarding this subspecies division. Researchers analyzed the type strain CCUG 34545T and its duplicate CCUG 41580T using 16S rRNA gene sequencing, DNA-DNA reassociation, whole-cell protein analysis, ribotyping, and phenotypic testing. Results consistently demonstrated that both strains cluster with L. sakei subspecies rather than L. curvatus, showing DNA-DNA reassociation values of 82-88% with L. sakei strains but only 30-39% with L. curvatus subsp. curvatus. The 16S rRNA gene sequences confirmed the strains belong to the L. sakei branch. Whole-cell protein profiles clearly grouped these strains with L. sakei subsp. carnosus reference strains. The authors conclude that L. curvatus subsp. melibiosus is a later synonym of L. sakei subsp. carnosus, and the subspecies division within L. curvatus should be abandoned.
Key findings
- Strain CCUG 34545T (L. curvatus subsp. melibiosus type strain) belongs to L. sakei based on DNA-DNA reassociation values of 82-88% with L. sakei strains versus only 30% with L. curvatus
- 16S rRNA gene sequence analysis and whole-cell protein profiles confirm clustering of L. curvatus subsp. melibiosus strains with L. sakei subsp. carnosus rather than L. curvatus
- Melibiose fermentation ability is not a reliable criterion for subspecies differentiation within L. sakei, as some L. sakei strains ferment melibiose and others do not
- L. curvatus should be recognized as a single species without subspecific division
- The original 1996 subspecies classification was based on incomplete molecular data lacking 16S rRNA gene analysis
This summary was generated automatically from the article PDF and is not part of the original publication. Refer to the PDF for the authoritative text.
Abstract
On the basis of phenotypic and DNADNA reassociation studies, strain CCUG 34545T has been considered to represent a distinct Lactobacillus curvatus subspecies, Lactobacillus curvatus subsp. melibiosus. However, in several independent studies dealing with Lactobacillus sakei and L. curvatus strains, the subspecies division of L. curvatus has been found to be controversial. The original study distinguishing the two subspecies within both L. curvatus and L. sakei also lacked 16S rRNA gene sequence analyses. Therefore, the taxonomic position of L. curvatus subsp. melibiosus CCUG 34545T was re-evaluated in a polyphasic taxonomy study that included 16S rRNA gene sequence analysis, DNADNA reassociation, DNA G+C content determination, numerical analysis of ribotypes and whole-cell protein patterns and the examination of some fundamental phenotypic properties. The results obtained indicate that strain CCUG 34545T and its duplicate, CCUG 41580T, are Lactobacillus sakei subsp. carnosus strains and that L. curvatus subsp. melibiosus is a later synonym of L. sakei subsp. carnosus.