Jeotgalicoccus pinnipedialis sp nov., from a southern elephant seal (Mirounga leonina)

A previously unknown Gram-positive, catalase-positive, facultatively anaerobic, non-spore-forming, coccus-shaped bacterium (A/G14/99/10(T)), originating from the mouth of a female southern elephant seal, was subjected to a taxonomic analysis. Comparative 16S rRNA gene-sequencing showed that the organism formed a hitherto unknown subline within the catalase-positive, low-G+C, Gram-positive cocci, exhibiting a specific association with species of the genus Jeotgalicoccus. Sequence divergence values of approximately 7%, together with phenotypic differences, showed the unknown bacterium to be distinct from the two described species of this genus, Jeotgalicoccus halotolerans and Jeotgalicoccus psychrophilus. Based on phenotypic and phylogenetic considerations, it is proposed that strain A/G14/99/10(T)=CCUG 42722(T)=CIP 107946(T) from the mouth of a seal be classified as the type strain of a novel species of the genus Jeotgalicoccus, Jeotgalicoccus pinnipedialis sp. nov.

Comparative Genomics of Early-Diverging Brucella Strains Reveals a Novel Lipopolysaccharide Biosynthesis Pathway

Brucella species are Gram-negative bacteria that infect mammals. Recently, two unusual strains (Brucella inopinata BO1(T) and B. inopinata-like BO2) have been isolated from human patients, and their similarity to some atypical brucellae isolated from Australian native rodent species was noted. Here we present a phylogenomic analysis of the draft genome sequences of BO1(T) and BO2 and of the Australian rodent strains 83-13 and NF2653 that shows that they form two groups well separated from the other sequenced Brucella spp. Several important differences were noted. Both BO1(T) and BO2 did not agglutinate significantly when live or inactivated cells were exposed to monospecific A and Mantisera against O-side chain sugars composed of N-formyl-perosamine. While BO1(T) maintained the genes required to synthesize a typical Brucella O-antigen, BO2 lacked many of these genes but still produced a smooth LPS (lipopolysaccharide). Most missing genes were found in the wbk region involved in O-antigen synthesis in classic smooth Brucella spp. In their place, BO2 carries four genes that other bacteria use for making a rhamnose-based O-antigen. Electrophoretic, immunoblot, and chemical analyses showed that BO2 carries an antigenically different O-antigen made of repeating hexose-rich oligosaccharide units that made the LPS water-soluble, which contrasts with the homopolymeric O-antigen of other smooth brucellae that have a phenol-soluble LPS. The results demonstrate the existence of a group of early-diverging brucellae with traits that depart significantly from those of the Brucella species described thus far. IMPORTANCE This report examines differences between genomes from four new Brucella strains and those from the classic Brucella spp. Our results show that the four new strains are outliers with respect to the previously known Brucella strains and yet are part of the genus, forming two new clades. The analysis revealed important information about the evolution and survival mechanisms of Brucella species, helping reshape our knowledge of this important zoonotic pathogen. One discovery of special importance is that one of the strains, BO2, produces an O-antigen distinct from any that has been seen in any other Brucella isolates to date.