Diversity of Weissella viridescens strains associated with "Morcilla de Burgos"

Unidentified heterofermentative lactic acid bacterium (LAB) isolates detected earlier in vacuum or modified atmosphere (MA) packaged "Morcilla de Burgos", a Spanish cooked meat product, were identified in the present study. In the previous study, these strains had been studied by numerical analysis of HindIII RFLP- and phenotyping. However, neither of these methods had resulted in species identification. Even these unknown strains clustered together in the numerical analysis of the RFLP patterns, none of the typically meat-associated LAB type strains had clustered together with them. The phenotyping was not more useful; according to the criteria used these strains with similar HindIII ribopatterns should have been divided into four different species in three different genera. To establish the taxonomic position of these isolates, 16S rRNA gene sequence analysis, numerical analysis of EcoRI and HindIII ribopatterns, and DNA-DNA hybridization experiments were done. The 16S rRNA genes sequences of three isolates possessed the highest similarities with the corresponding sequences of Weissella species and in the phylogenetic analysis Weissella viridescens was their closest phylogenetic neighbor. However, in the numerical analysis of either HindIII or EcoRI ribopatterns the W. viridescens type strain did not cluster with these isolates. Nevertheless, the high (from 75% to 83%) DNA-DNA reassociation values between the strains studied and the W. viridescens type strain confirmed that these strains belong to the latter species. The somewhat divergent results of the pheno- and HindIII ribotyping indicate that W. viridescens is far more heterogeneous species than previously reported.