Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “NOCARDIA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed1999

Mycolic acid analysis in Nocardia species. The mycolic acid compositions of Nocardia asteroides, N. farcinica, and N. nova.

Mycolic acids from twelve Nocardia species were analyzed for structure using capillary gas chromatography and mass spectrometry. This high-resolution procedure permitted good separation of the trimethylsilyl (TMS) ether derivatives of mycolic acid methyl ester according to the total number of carbon and double bonds. The profiles of the mycolic acid molecular species were used as models to illustrate the difference in the structures of each species, even in the case of N. asteroides complex; N. asteroides, N. farcinica and N. nova. Although N. asteroides and N. farcinica had similar lengths of carbon skeleton, i.e., 51.9-53.7 was the average carbon number (Av.Nc.), they had different compositions of unsaturated acids. Mycolic acids from N. asteroides were composed of abundant saturated acids and less than 1% tetraenoic acids; mycolic acids from N. farcinica were composed of unsaturated acids, which were composed of abundant dienoic acids, 2-12% of tetraenoic acids and a trace of pentaenoic acids. In contrast, Av.Nc. of mycolic acids from N. nova were 55.7-56.3, which were relatively longer than those from N. asteroides or N. farcinica. Regarding the characteristics of the structure of alpha-branch, major components were C16:0 and C18:0 for N. asteroides 23206T, and C16:0 and C14:0 for N. farcinica 23157T, respectively. The presence of monounsaturated alpha-branch (C18:1 and C16:1) was characteristic of N. nova.

Gas Chromatography-Mass Spectrometry↗
PubMed1967

Linkage and segregation of unselected markers in matings of Nocardia erythropolis with Nocardia canicruria.

The segregation of unselected genes expressing resistance or susceptibility to acriflavine, erythromycin, streptomycin, and tetracycline was analyzed in selected prototrophic recombinants resulting from matings of Nocardia erythropolis and N. canicruria. The organisms were shown to be functionally haploid and appeared to contain not more than one genome. It was postulated that all observed genes were present in a linear linkage group. The ordering of the genes in N. erythropolis was: tetB10 eryB9 his-3 purA1 acr-2 strA1 (respectively, resistance to tetracycline and erythromycin, deficiency for histidine and for purine, and resistance to acriflavine and streptomycin). The ordering of the genes in N. canicruria was: purB2 tetA9 eryA7 acr-11 strB2 (respectively, deficiency for purine, and resistance to tetracycline, erythromycin, acriflavine, and streptomycin). Excluding the genes for acriflavine resistance, acr-2 and acr-11, resistance loci in N. erythropolis were not allelic to and showed lateral displacement from genes controlling phenotypically similar resistance in N. canicruria. Evidence for some lack of homology between N. erythropolis and N. canicruria genomes was found. Recombination phenomena between the nocardial species was postulated to occur as a result of formation of a heterogenomic zygote in which new combinations were produced. Production of selectable, haploid recombinants was ascribed to subsequent haploidization of the zygote.

Chromosome Mapping↗
PubMed1978

A genetic approach to the biosynthesis of the rifamycin-chromophore in Nocardia mediterranei. I. Isolation and characterization of a pentose-excreting auxotrophic mutant of Nocardia mediterranei with drastically reduced rifamycin production.

The mutant under study, designated A8, is derived from a Nocardia mediterranei strain, N813, which is a high rifamycin B producer. A8 is auxotrophic for aromatic amino acids and produces much less rifamycin B than the parent. A mixture of pentoses with D (--) ribulose as the main product is accumulated in the fermentation broth of this mutant. It was shown to be affected in its transketolase activity as no formation of D-sedoheptulose -7P from pentose-phosphates could be detected in vitro using crude extracts. The only pathway so far known which is derived from D-sedoheptulose-7P is the shikimate pathway leading to aromatic amino acids and vitamins. Biochemical and genetic investigations with mutant A8, which is defective in both the biosynthesis of rifamycins and the biosynthesis of shikimate pathway products, show that the seven-carbon amino unit of the rifamycin-chromophore must be derived from an intermediate of the shikimate pathway.

Culture Media↗
PubMed1978

A genetic approach to the biosynthesis of the rifamycin-chromophore in Nocardia mediterranei. II. Isolation and characterization of a shikimate excreting auxotrophic mutant of Nocardia mediterranei with normal rifamycin-production.

The mutant under study, designated A10, is derived from a Nocardia mediterranei strain, N813, which is a high rifamycin B producer. A10 is auxotrophic for aromatic amino acids but unlike A8 (see preceding paper) produces the same amount of rifamycin B as the parent. Shikimic acid and 3-dehydroshikimic acid are accumulated in the fermentation broth of this mutant. It was shown to be blocked in one of the enzymes leading from shikimate to chorismate. No formation of shikimate-3-phosphate from shikimate and ATP could be detected in vitro using crude extracts of this mutant and of the parent. As mutant A10 is only defective in the biosynthesis of aromatic amino acids and not in the biosynthesis of rifamycins it would appear that the seven-carbon amino unit of the rifamycin-chromophore must be derived from an intermediate of the shikimate pathway not behind shikimate. By referring to the results of the preceding paper it can be seen that the origin of this moiety can definitely be localized between 3-deoxy-D-arabinoheptulosonic acid-7-phosphate and shikimate.

Culture Media↗
PubMed1970

Structure des parois cellulaires des nocardia. I-isolement et composition des parois de Nocardia kirovani.

Nocardia kirovani cell walls possess a lipidic fraction, a lipolysaccharidic fraction and a peptidoglycan. The lipidic part is composed of glycerides, C(16) and C(18) free fatty acids, nocardic acids and of a carotenoid pigment. The lipopolysaccharidic part is composed of an arabinogalactan esterified by nocardic acids. The glycan strand consists of alternating 1-->4 linked N-acetylglucosamine and N-glycolylmuramic acid residues substituted by a peptide subunit in which the aminoacids Ala, Glu, meso-Dap are present in the molar proportions 1,7:1,2:1.

Journal Article↗