Carnimonas nigrificans gen. nov., sp. nov., a bacterial causative agent for black spot formation on cured meat...

Nine different strains, CTCBS1T or CTCBS9, were identified to be the causative agents of black spots on the surface of raw cured meat products. The formation of black spots under aerobic conditions is reproducible upon reinoculation of meat products with any of these strains, indicating that they are the causative agent. The strains were Gram-negative, catalase-positive and obligately aerobic rods. The G+C content of DNA of strain CTCBS1T is 56.0 +/- 0.3 mol%. The content of non-polar main fatty acids were 16:0, 16:1, 18:1 and 19:0 cyc. Its phylogenetic position was elucidated by comparative sequence analysis of the 16S rRNA gene. Overall sequence similarity to other bacteria does not exceed 93.3%. Isolate CTCBS1T clustered phylogenetically within the gamma-subclass of the Proteobacteria and is closely related to members of Halomonas (90:5-91.9%) and to Zymobacter palmae (93.3%). A genetic homogeneity of the nine strains was demonstrated by M13 random amplified polymorphic DNA-PCR, whereas differentiation from other genera, e.g. Zymobacter and Pseudomonas, could easily be achieved by their chemotaxonomic characteristics. Taxonomic data revealed the status of a separate genus for which the name Carnimonas gen. nov., sp., nov. is proposed. Despite chemotaxonomic and physiological similarities, the new genus is at present not a member of the family Halomonadacease because of the lack of two out of 15 descriptive 16S rRNA signature sequences. The first member of the new genus is Carnimonas nigrificans. The use of a specific, 16S rRNA-targeted oligonucleotide primer allowed the identification of all nine strains of C. nigrificans in a PCR assay. Toxicological studies showed no pathogenic potential for C. nigrificans strain CTCBS1T (CECT 4437T).