Mycobacterium alvei (ω-1)-methoxy mycolic acids: Absolute stereochemistry and synthesis.

Cells of Mycobacterium alvei are known to contain a unique set of mycolic acids with a (ω-1)-methoxy group; although the various enzymes in the biosynthesis of other types of mycolic acid have been widely studied, the biosynthetic route to this substituent is unclear. We now define the stereochemistry of the (ω-1)-methoxy fragment as R, and describe the synthesis of a major R-(ω-1)-methoxy-mycolic acid and its sugar esters, and of two natural M. alvei diene mycolic acids.

DNA sequencing by Microseq kit targeting 16S rRNA gene for species level identification of mycobacteria.

BACKGROUND & OBJECTIVES: Identification of mycobacteria to the species level is of therapeutic significance. Conventional methods are laborious and time consuming so we did 16S rRNA sequencing using a commercial MicroSeq sequencing kit, which includes DNA sequencing with software package for identification and phylogenetic analysis of clinical mycobacterial isolates. METHODS: A total of 47 mycobacteria were tested by both conventional and genotypic method using commercially available MicroSeq 500 amplification kit assay. The identification was determined by comparing the 500 bp amplified product of 16S rDNA sequence to the MicroSeq database. RESULTS: The phenotypic identification was concordant with genotypic identification in 33 (70.2%) isolates of 14 Mycobacterium tuberculosis, 11 M. fortuitum, 7 M. abscessus and 1 M. duvalii. For the discrepant isolates, identification was possible only by DNA sequencing in 14 (29.7%) isolates. The 14 discrepant isolates were 5 M. farcinogenes, 3 M. genavense, 2 M. species. nov and 1 each of M. fortuitum, M. immuogenum, M. simiae and M. wolinskyi. Of these, five were uncommon species that were difficult to identify by phenotypic method. INTERPRETATION & CONCLUSION: The MicroSeq DNA sequencing is an excellent tool for species identification of mycobacteria, which reduces the turn around time, makes repeat analysis easy as compared to phenotypic identification specially for mycobacterial isolates with ambiguous biochemical profiles.

Developmental potential of Frankia vesicles.

The ability of nitrogenase-containing Frankia sp. strain CpI1 vesicles to regrow vegetative hyphae is demonstrated. Vesicles attached to hyphae in N2-fixing CpI1 cultures and sucrose gradient-isolated vesicles exhibited hyphal outgrowths when incubated in certain defined liquid media. Single or multiple hyphal extensions grew out from the vesicles.

[Taxonomic position of the genus Mycococcus]. / O taksonomicheskom polozhenii roda Mycococcus.

An attempt to elucidate the taxonomic position of the genera Mycococcus has been made. For this purpose the full range of the taxonomically important properties were investigated among microbial cultures preliminary identified as Mycococci. As a result of comparison Mycococcus with Micrococcus the taxonomic status of the genus Mycococcus was no longer confirmed. On the grounds of the published data and the author's experimental results it was concluded that genus Micrococcus was closely related to genus Arthrobacter. The possibility to place the genus Micrococcus within the group of coryneform bacteria is being discussed.

[Species composition of mycococci]. / O vidovom sostave mikokokkov.

The phenotypical similarity between 34 microbial strains was determined, and they were classified on the principle of maximal general similarity in 70 traits. All the strains were subdivided into three groups within which the similarity of the strains was not less than 85%. The groups correspond to the species Mycococcus capsulatus, M. ruber, and Mycobacterium brevicale. The results of the investigation suggest that the group of mycococci possesses a considerable number of characteristics which make it possible to consider it as a separate microbial genus. However, the principle of equal weight can be hardly applied to the taxonomy of mycococci since sharp variations in many traits do not permit to differentiate between specific and strain differences. Morphological and cultural properties still remain the most reliable criteria of the genus Mycococcus.

[Spectrophotometric characteristics of the coccoid forms of actinomycetes]. / Spektrofotometricheskie kharakteristiki kokkovykh form aktinomitsetov

IR spectra of thw whole cells of the coccoid forms (Mycococcus and Micrococcus) isolated from lithophilous lichen were compared with IR spectra of the collection cultures of Micrococcus and Arthrobacter. Generic spectral characteristics of Mycococcus and Micrococcus are presented. Spectral heterogeneity within the genus Arthrobacter complicates the diagnosis. The cultures of the Mycococcus genus were divided into three groups according to their spectral characteristics. Spectral scans of the studied coccoid forms differ from the scans of the mycelial actinomycetes, and their intensities within the range of 900-1200 cm-1 (lipids) decrease in the series Mycococcus, Arthrobacter, Micrococcus.