PubMed Health⌕ Search

PubMed · 10068784

Rhodococcal systematics: problems and developments.

Abstract

Various approaches that have been used in the development of a system of classification for the genus Rhodococcus are discussed. The application of chemotaxonomic, molecular systematic and numerical phenetic methods have greatly contributed to improvements in the systematics of rhodococci and related mycolic-acid containing actinomycetes. The genus currently encompasses twelve validly described species but improved diagnostic methods are needed to distinguish between them. In addition, evidence from 16S ribosomal RNA sequencing suggests that the genus is still heterogeneous.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

M Goodfellow, G Alderson, J Chun. Rhodococcal systematics: problems and developments.. https://doi.org/10.1023/a%3A1001730725003

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Isolation and characterization of two novel species Neorhizobium fuzhouense sp. nov. and Neotabrizicola paludis sp. nov.

Two novel aerobic bacterial strains, designated SGZ-38T and sgz301269T, were isolated from the root of Pennisetum sp. and paddy soil, respectively. Strain SGZ-38T grew at 10-40 ℃ (optimum 30 °C) and pH 5.0-12.0 (optimum 6.5) and tolerated up to 1.0% NaCl (w/v), whereas strain sgz301269T grew at 15-37 °C (optimum 30 °C), pH 5.0-9.5 (optimum 7.0) and 0-2% NaCl (optimum 0%). Phylogenetic trees based on the 16S rRNA gene and genomes placed both strains into distinct lineages, forming separated clades from their closest relatives. Strain SGZ-381T exhibited the highest 16S rRNA gene similarities to "Neorhizobium deserti" ACCC 61627T (97.4%), and strain sgz301269T had the highest 16S rRNA gene sequence similarity to Neotabrizicola shimadae N10T (97.6%). The respiratory quinone in both strains was ubiquinone-10. The main fatty acids of SGZ-381T were Summed feature 8, Summed feature 2 and C16:0, whereas strain sgz301269T included C10:0 3OH, C18:0 3OH and Summed feature 8. The DNA G+C content of SGZ-381T and sgz301269T was 62.1% and 65.5%, respectively. The average nucleotide identity and digital DNA-DNA hybridization values between each strain and their respective closest species were 74.6% and 20.1%, 75.3% and 17.4% respectively, below the thresholds for species delineation. Based on the comprehensive chemotaxonomic, phylogenetic, and phenotypic evidence, proposed names of the novel strains are Neorhizobium fuzhouense sp. nov. (type strain SGZ-381T=GDMCC1.4207T=JCM 36770T), Neotabrizicola paludis sp. nov. (type strain sgz301269T=MCCC 1K09178T=KCTC 8856T).

Bacterial Typing Techniques↗

Rapid identification of 11 human intestinal Lactobacillus species by multiplex PCR assays using group- and species-specific primers derived from the 16S-23S rRNA intergenic spacer region and its flanking 23S rRNA.

Rapid and reliable two-step multiplex polymerase chain reaction (PCR) assays were established to identify human intestinal lactobacilli; a multiplex PCR was used for grouping of lactobacilli with a mixture of group-specific primers followed by four multiplex PCR assays with four sorts of species-specific primer mixtures for identification at the species level. Primers used were designed from nucleotide sequences of the 16S-23S rRNA intergenic spacer region and its flanking 23S rRNA gene of members of the genus Lactobacillus which are commonly isolated from human stool specimens: Lactobacillus acidophilus, Lactobacillus crispatus, Lactobacillus delbrueckii (ssp. bulgaricus and ssp. lactis), Lactobacillus fermentum, Lactobacillus gasseri, Lactobacillus jensenii, Lactobacillus paracasei (ssp. paracasei and ssp. tolerans), Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus rhamnosus and Lactobacillus salivarius (ssp. salicinius and ssp. salivarius). The established two-step multiplex PCR assays were applied to the identification of 84 Lactobacillus strains isolated from human stool specimens and the PCR results were consistent with the results from the DNA-DNA hybridization assay. These results suggest that the multiplex PCR system established in this study is a simple, rapid and reliable method for the identification of common Lactobacillus isolates from human stool samples.

Bacterial Typing Techniques↗

Genomic diversity among Vibrio cholerae O139 strains isolated in Bangladesh and India between 1992 and 1998.

In order to assess the extent of genomic diversity among Vibrio cholerae O139 strains, restriction fragment length polymorphisms in two genetic loci, rrn and ctx, were studied. Analysis of 144 strains isolated from different regions of Bangladesh and India between 1992 and 1998 revealed the presence of at least six distinct ribotypes (B-I through B-VI) of which three were new ribotypes, and one of these was represented by a nontoxigenic O139 strain. Strains of ribotypes B-I through B-V shared 11 different CTX genotypes (A through K). Antimicrobial resistance patterns of the strains varied independently of their ribotypes and CTX genotypes. Results of this study suggest that V. cholerae O139 is undergoing rapid genetic changes leading to the origination of new variants, and temporal changes in antimicrobial resistance patterns may be contributing to the selection of different variants.

Bacterial Typing Techniques↗