ABSTRACT
The presence of bona fide outer membranes in members of the class Negativicutes is anomalous as phylogenetic analyses place this class within the phylum Firmicutes. To explore the relationships of a representative member of Negativicutes, we have performed a whole proteome BLAST analysis of Acidaminococcus intestini, which indicates that a substantial proportion (7 %) of the A. intestini proteome is closely related to sequences from members of the phylum Proteobacteria. In addition, we have identified key proteins involved in outer membrane biogenesis in A. intestini. This work highlights the need for further studies to define the relationships and evolutionary history of the Negativicutes.
Subject(s)
Acidaminococcus/classification , Bacterial Outer Membrane Proteins/biosynthesis , Proteobacteria/classification , Proteome/genetics , Acidaminococcus/genetics , Acidaminococcus/metabolism , Bacterial Outer Membrane Proteins/genetics , Base Sequence , Phylogeny , Proteobacteria/genetics , Proteobacteria/metabolism , ProteomicsABSTRACT
Acidaminococcus intestini belongs to the family Acidaminococcaceae, order Selenomonadales, class Negativicutes, phylum Firmicutes. Negativicutes show the double-membrane system of Gram-negative bacteria, although their chromosomal backbone is closely related to that of Gram-positive bacteria of the phylum Firmicutes. The complete genome of a clinical A. intestini strain is here presented.
Subject(s)
Acidaminococcus/genetics , Genome, Bacterial , Acidaminococcus/classification , Acidaminococcus/isolation & purification , Base Sequence , Evolution, Molecular , Gram-Negative Bacterial Infections/microbiology , Humans , Molecular Sequence DataABSTRACT
Eleven strains of a hitherto unknown, Gram-negative, anaerobic coccus were recovered from various human clinical samples of patients hospitalized in two geographically distant French hospitals. These strains displayed the morphology and growth characteristics of those related to the genus Acidaminococcus. The clinical isolates shared at least 99.9 and 99.7 % of their nucleotide positions in the 16S and 23S rRNA gene sequences, respectively. They displayed 95.6 and 88.9 % 16S and 23S rRNA gene sequence similarities, respectively, with Acidaminococcus fermentans. The 16S rRNA-based phylogeny revealed that all the clinical isolates grouped in a statistically well supported cluster separate from A. fermentans. Enzymic activity profiles as well as metabolic end product patterns, including propionic acid production, differentiated the novel bacteria from A. fermentans. Finally, phenotypic, genotypic and phylogenetic data, including large-scale chromosome structure and DNA G+C content, supported the proposal of a novel species of the genus Acidaminococcus, for which the name Acidaminococcus intestini sp. nov. is proposed. The type strain is ADV 255.99(T) (=AIP 283.01(T)=CIP 108586(T)=CCUG 50930(T)).
