Summary auto-generated
This taxonomic study analyzed 39 bacterial strains from Malaysian foods and clinical samples using a polyphasic approach to clarify relationships within the genus Weissella. The strains, primarily from fermented foods (tapai, chili bo) and clinical samples from humans and animals, were characterized using classical phenotyping, whole-cell protein electrophoresis, 16S and 23S rDNA RFLP analysis, and DNA-DNA hybridization. The research revealed two distinct species: the previously known Weissella confusa and a novel species designated Weissella cibaria sp. nov. Although the two species shared 99.2% 16S rDNA sequence similarity, DNA-DNA hybridization values were below 49%, confirming separate species status. W. cibaria differed from W. confusa in peptidoglycan structure, growth temperature capabilities, and some carbohydrate fermentation patterns. Notably, W. cibaria could grow at 45°C, unusual among Weissella species. The study found no consistent clustering of strains by food or clinical origin, indicating both species occupy diverse habitats. The research demonstrates the importance of polyphasic taxonomic approaches for resolving controversial classifications, particularly when morphological and biochemical characteristics are similar.
Key findings
- Two distinct Weissella species were identified: W. confusa (previously known) and W. cibaria sp. nov., despite 99.2% 16S rDNA sequence similarity, confirmed by DNA-DNA hybridization values below 49%
- W. cibaria has a unique peptidoglycan type A3α structure with serine-containing interpeptide bridge, distinct from W. confusa
- W. cibaria uniquely grows at 45°C among Weissella species and shares diverse habitats ranging from fermented foods to clinical samples with W. confusa
- Polyphasic analysis using protein electrophoresis and ClaI/HindIII ribotyping provided reliable species-level differentiation, while 16S rDNA sequence comparison alone was insufficient due to high similarity between species
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
A taxonomic study was conducted to clarify the relationships of two bacterial populations belonging to the genus Weissella. A total of 39 strains originating mainly from Malaysian foods (22 strains) and clinical samples from humans (9 strains) and animals (6 strains) were analysed using a polyphasic taxonomic approach. The methods included classical phenotyping, whole-cell protein electrophoresis, 16S and 23S rDNA RFLP (ribotyping), determination of 16S rDNA sequence homologies and DNA--DNA reassociation levels. Based on the results, the strains were considered to represent two different species, Weissella confusa and a novel Weissella species, for which the name Weissella cibaria sp. nov. is proposed. Weisella confusa possessed the highest 16S rDNA sequence similarity to Weisella cibaria, but the DNA--DNA reassociation experiment showed hybridization levels below 49% between the strains studied. The numerical analyses of Weisella confusa and Weisella cibaria strains did not reveal any specific clustering with respect to the origin of the strains. Based on whole-cell protein electrophoresis, and ClaI and HindIII ribotyping patterns, food and clinical isolates were randomly located in the two species-specific clusters obtained.