Enterococcus dispar

Abstract: The partial 16S rRNA sequences of two unknown human enterococcal isolates were determined by reverse transcription in an attempt to clarify their taxonomic position. The sequence data indicate that they belong to a hitherto unknown species of Enterococcus, for which the name Enterococcus dispar sp. nov. is proposed. The type strain is NCIMB 13000.

Abstract: The taxonomic position of strain LMG 13590(T), originally isolated from dog faeces and classified as Enterococcus dispar in the BCCM/LMG Bacteria Catalogue, was reinvestigated. This strain and 12 recent isolates from faecal samples of healthy dogs occupied a clearly separate position when investigated with multilocus sequence analysis (MLSA) of the genes encoding the alpha subunit of ATP synthase (atpA), RNA polymerase alpha subunit (rpoA) and phenylalanyl-tRNA synthase alpha subunit (pheS). The 16S rRNA gene sequence of one representative strain showed highest similarities of 98-99% with E. dispar LMG 13521(T), Enterococcus canis LMG 12316(T) and Enterococcus asini LMG 18727(T). A further polyphasic taxonomic study based on whole-cell protein fingerprinting, DNA-DNA hybridization and biochemical features demonstrated that the 13 enterococcal dog faecal strains represent a single, novel Enterococcus species for which the name Enterococcus canintestini sp. nov. is proposed. The type strain is LMG 13590(T) (=CCM 7285(T)).

Abstract: Enterococci are Gram-positive, catalase-negative, facultatively anaerobic cocci typically associated with the gastrointestinal tract of humans and animals. Enterococcus strains are also present in many food products, in fermented food, on plants, and in water and soil (1, 14, 15, 17, 22). Enterococcus faecium and Enterococcus faecalis are among the leading causes of nosocomial infections, and the recent increase in antibiotic-resistant strains has caused serious concern (51). The genus was described in 1984 (39), and on the basis of 16S rRNA gene sequence analysis, several phylogenetic groups have been distinguished (E. faecium, E. faecalis, Enterococcus avium, Enterococcus casseliflavus, Enterococcus dispar, Enterococcus saccharolyticus, and Enterococcus cecorum species groups) (16, 22, 52). Several novel species have recently been described (24, 30, 41, 43, 44, 45), and 40 Enterococcus species are currently recognized (13) (last full update, 8 September 2010). The identification of enterococcal species is often challenging. Conventional phenotypic characterization of enterococci is laborious and may present problems in the interpretation of the results or even cause errors, because many enterococcal species vary by only one phenotypic trait (23, 27, 38). Several molecular methods have been used to differentiate Enterococcus species. Among these, numerical taxonomic methods (3, 12, 31) or sequence-based methods (28, 29, 35) have been the most commonly used. Numerical analysis of ribopatterns is one of the taxonomic approaches that has been successfully applied in the identification of enterococci (18, 19, 24, 25, 36, 42). However, previous studies have included only a limited number of enterococcal species, and to our knowledge, the method has not yet been used to establish species identification libraries. Recently, Naser et al. (29) applied multilocus sequence analysis to differentiate Enterococcus species. DNA-directed RNA polymerase subunit A (rpoA) and phenylalanyl-tRNA synthetase α chain (pheS) gene sequences were both able to discriminate even closely related Enterococcus species showing very high 16S rRNA sequence similarity. In previous studies by our group, several isolates of lactic acid bacteria (LAB) from modified-atmosphere-packaged (MAP) broiler products (5) and a broiler processing plant (49) remained unidentified by use of a database constructed from the HindIII ribotypes of 260 LAB type and reference strains, including 33 strains of Enterococcus spp. (4, 6, 26). This study was designed to identify these strains to the species level and provide data on the LAB species associated with broiler production. Sequencing of the 16S rRNA gene, a restriction fragment polymorphism (RFLP) database combining EcoRI with HindIII ribopatterns, and sequence analysis of housekeeping genes pheS and rpoA were applied. In these analyses, five strains did not cluster together with any known Enterococcus type strain, and their taxonomic status was investigated using a polyphasic taxonomic approach.

Abstract: Aims: To improve the limited information on the composition of the faecal Gram-positive coccal flora of healthy dogs by the use of a molecular identification method. Methods and Results: Faecal swabs were collected for the selective isolation of Gram-positive coccal strains. Colonies with enterococcal- and streptococcal-like morphology were identified by tRNA intergenic length polymorphism analysis (tDNA-PCR). Fourteen known species belonging to three genera (Enterococcus, Streptococcus and Weissella) and one alleged new enterococcal species were found. Conclusions: The faecal flora of dogs comprises an unusually broad diversity of culturable Gram-positive coccal species with Enterococcus faecalis being most frequently present followed by not less than six other species of about equal importance. Significance and Impact of the Study: Many human- and animal-associated enterococci and streptococci are also present in dog faeces together with the largely uncharacterized Weissella cibaria and a group of strains resembling Enterococcus dispar, but representing a distinct and hitherto unknown species. Phenotypic characteristics of the latter two species were determined and the test results were compared with the species descriptions of W. cibaria and E. dispar respectively.