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Biomedical subjects

Y Okami

Publications and source records attributed to Y Okami.

At least 55 records · Page 3Linked to original sources
PubMed1986

Production of novel antibiotic, dopsisamine, by a new subspecies of Nocardiopsis mutabilis with multiple antibiotic resistance.

An actinomycete isolate designated as TS-1980 with multiple resistance to aminoglycoside antibiotics was found to produce novel antibiotics. The strain showed taxonomic features identical to the type strain of Nocardiopsis mutabilis except for the temperature range for growth and the utilization of mannitol and raffinose. Based on the capability of growing at lower temperature range, the strain was named N. mutabilis subsp. cryophilis subsp. nov. Physico-chemical and biological characterization of a purified antibiotic revealed its novel polyamine-type nature with a broad antimicrobial activity. The antibiotic was named dopsisamine.

Actinomycetales↗
PubMed1985

New antibiotic-producing streptomycetes, selected by antibiotic resistance as a marker. I. New antibiotic production generated by protoplast fusion treatment between Streptomyces griseus and S. tenjimariensis.

A novel antibiotic was found after performing an interspecific fusion treatment between Streptomyces griseus and S. tenjimariensis by the selection of clones with a unique antibiotic resistance. Nonantibiotic-producing mutants of streptomycin (SM)-producing S. griseus SS-1198 with resistance to SM and istamycin (IS)-producing S. tenjimariensis SS-939 with resistance to kanamycin (KM) were protoplasted, mixed with polyethyleneglycol and regenerated. Resistant clones to both SM and KM were found among spores of the regenerated culture at a frequency of 10(-6). Their growth appearance was identical with that of S. griseus. Antibiotic productivity was found only in clones resistant to both 20 approximately 50 micrograms/ml of KM and 400 micrograms/ml of SM. The antibiotic produced by a selected strain, SK2-52, proved to be different from SM and IS.

Anti-Bacterial Agents↗
PubMed1985

New antibiotic-producing streptomycetes, selected by antibiotic resistance as a marker. II. Features of a new antibiotic-producing clone obtained after fusion treatment.

A new antibiotic-producing Streptomyces strain SK2-52 obtained by a protoplast fusion treatment between Streptomyces griseus NP1-1 and S. tenjimariensis NM16 showed taxonomical features identical with those of S. griseus. The strain resistant to wider range of aminoglycoside antibiotics than the parental strains. This multiple resistance corresponded to the activities of streptomycin kinase and acetyltransferase which were probably derived from S. griseus NP1-1. Clones with fast-growth and reduced antibiotic productivity frequently segregated from strain SK2-52, while their antibiotic resistance was stable. The results suggest that the fusion treatment caused a genetic change in S. griseus which enhanced the expression of genes for unique multiple resistance to aminoglycoside antibiotics and also induced new antibiotic production.

Anti-Bacterial Agents↗
PubMed1984

Plasmid variability in the istamycin producing strains of Streptomyces tenjimariensis.

Three strains of istamycin-producing Streptomyces tenjimariensis were isolated over a period of time from soils at the same location and were found to have three different types of plasmid profiles. Protoplast fusion between two of these strains provided a clone harboring a smaller plasmid not present in the parent strains. None of the plasmids had restriction sites for EcoR I and Hind III. Most of the plasmids had one or two restriction sites for BamH I, Bcl I, Bgl II, Kpn I, Pst I and Pvu II, and more than two restriction sites for Sal I and Sst II. Plasmid restriction maps and Southern hybridization experiments revealed that pST2, pST12 and pST22 were identical, as were pST10 and pST20. In addition, it was revealed that pST1, pST1, pST11 and pST21 were related to each other.

Aminoglycosides↗
PubMed1983

Multiple resistance to aminoglycoside antibiotics in actinomycetes.

Actinomycetes were characterized in terms of resistance to 11 different aminoglycoside antibiotics (AGs). Strains freshly isolated in AG containing media showed wide varieties of multiple AG resistance, while the majority of ISP (International Streptomyces Project) cultures and the actinomycete strains isolated in an AG free medium were susceptible to all or most of the AGs tested. Marked characteristics were noted in multiple AG resistance of gray and yellow colored actinomycetes and AG-producing strains. In gray colored isolates, multiple resistance to kanamycin A, dibekacin, ribostamycin, butirosin A, istamycin A and neamine was often observed. Yellow colored isolates having multiple AG resistance were mostly resistant to neamine, ribostamycin and streptomycin and, to a lesser extent, istamycin A, dibekacin and butirosin A. Most of the AG producers tested showed unique multiple AG resistance patterns.

Actinomycetales↗
PubMed1983

Marinactan, antitumor polysaccharide produced by marine bacteria.

Extracellular polysaccharides of marine bacteria were screened for their antitumor activity against sarcoma-180 solid tumor in mice. An active polysaccharide was purified and named marinactan. The producing microorganism has a typical marine bacterial nature requiring sea water for growth and was identified as Flavobacterium uliginosum. Marinactan is a novel heteroglycan consisting of glucose, mannose and fucose in a ratio of approximately 7:2:1. Marinactan, 10-50 mg mg/kg daily for 10 days i.p., produced 70-90% inhibition of the growth of solid sarcoma 180. Complete regression of the tumor was observed in some treated mice. Its administrations before and after tumor transplantation showed almost the same inhibitory effect. Marinactan prolonged markedly the survival period of mice bearing ascites sarcoma 180.

Animals↗
PubMed1982

Mechanism of resistance to aminoglycoside antibiotics in nebramycin-producing Streptomyces tenebrarius.

Streptomyces tenebrarius ISP 5477, which produces nebramycins, was highly resistant to the following aminoglycoside antibiotics: neamine, ribostamycin, butirosin A, neomycin B, paromomycin, kanamycin A, dibekacin, gentamicin C complex, lividomycin A, istamycin B and streptomycin. Polyphenylalanine synthesis on the ribosomes of this strain was highly resistant to neamine, ribostamycin, butirosin A, kanamycins A, B and C, dibekacin, gentamicin C complex and istamycin B, moderately resistant to lividomycin A and streptomycin, but sensitive to neomycin B and paromomycin. Moreover, cell free extract of the strain contained phosphotransferase and N-acetyltransferase. The former enzyme was confirmed to be an aminoglycoside 6-phosphotransferase which inactivated streptomycin; the latter inactivated kanamycins B and C, dibekacin, neamine, neomycin B, paromomycin, lividomycin A, butirosin A and ribostamycin, but did not inactivate kanamycin A, gentamicin C complex and sagamicin, suggesting an aminoglycoside 2'-acetyltransferase. These results indicated that the high resistance of S. tenebrarius ISP 5477 to a wide range of aminoglycoside antibiotics is due to ribosomal resistance and to the inactivating enzymes, aminoglycoside N-acetyltransferase(s) and aminoglycoside 6-phosphotransferase.

Acetyltransferases↗
PubMed1981

Resistance mechanisms of kanamycin-, neomycin-, and streptomycin-producing streptomycetes to aminoglycoside antibiotics.

Streptomyces kanamyceticus ISP5500, S. fradiae ISP5063 and S. griseus ISP5236, which produce kanamycin, neomycin or streptomycin respectively, were highly resistant to the antibiotics they produced. Polyphenylalanine synthesis in cell free systems was also resistant to the action of the antibiotics. Reciprocal exchange between ribosomes and S150 fractions from the three strains revealed that the S150 fraction of each strain had an enzyme activity that inactivated the appropriate antibiotic whereas the ribosomes were susceptible to the antibiotics. It was concluded that the resistance of the in vitro polyphenylalanine synthesizing systems of these antibiotics was due to the presence of inactivating enzymes. Furthermore, S. fradiae and S. kanamyceticus were highly resistant to aminocyclitol-containing aminoglycoside antibiotics other than those produced by the two strains. In these cases, the inactivating enzymes were found to have a major role in the resistance mechanism. However, the resistance of S. kanamyceticus ISP5500 to streptomycin seems to be due to resistance at the ribosomal level.

Aminoglycosides↗
PubMed1981

Self-resistance of a Streptomyces which produces istamycins.

Streptomyces tenjimariensis SS-939, a producer of istamycins, is highly resistant to its own antibiotics and grows in Tryptic Soy Broth containing istamycin A or B at 3,000 microgram/ml. No istamycin-inactivating enzyme was detected in extracts of strain SS-939. Polyphenylalanine synthesis in an in vitro system, consisting of the S-150 fraction and ribosomes prepared from strain SS-939, was not inhibited by 200 microgram/ml of istamycins. Using reciprocally reconstituted systems consisting of S-150 fractions and ribosomes from strain SS-939 and those from Streptomyces griseus ISP5236 (istamycin-sensitive strain), ribosomes of strain SS-939 were found to be resistant to istamycins. Thus, ribosomes have the main role in the self-resistance mechanism of S. tenjimariensis SS-939.

Aminoglycosides↗