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Characterization of Dielectric Nanocomposites with Electrostatic Force Microscopy. SCANNING 2017; 2017:4198519. [PMID: 29109811 PMCID: PMC5661829 DOI: 10.1155/2017/4198519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 06/22/2017] [Accepted: 08/03/2017] [Indexed: 05/12/2023]
Abstract
Nanocomposites physical properties unexplainable by general mixture laws are usually supposed to be related to interphases, highly present at the nanoscale. The intrinsic dielectric constant of the interphase and its volume need to be considered in the prediction of the effective permittivity of nanodielectrics, for example. The electrostatic force microscope (EFM) constitutes a promising technique to probe interphases locally. This work reports theoretical finite-elements simulations and experimental measurements to interpret EFM signals in front of nanocomposites with the aim of detecting and characterizing interphases. According to simulations, we designed and synthesized appropriate samples to verify experimentally the ability of EFM to characterize a nanoshell covering nanoparticles, for different shell thicknesses. This type of samples constitutes a simplified electrostatic model of a nanodielectric. Experiments were conducted using either DC or AC-EFM polarization, with force gradient detection method. A comparison between our numerical model and experimental results was performed in order to validate our predictions for general EFM-interphase interactions.
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[THE ROLE OF (p)ppGpp MOLECULES IN FORMATION OF "STRICT RESPONSE" IN BACTERIA AND BIOSYNTHESIS OF ANTIBIOTICS AND MORPHOLOGICAL DIFFERENTIATION IN ACTINOMYCETES]. TSITOLOGIIA I GENETIKA 2016; 50:65-74. [PMID: 27281927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Strict response is a pleiotropic physiological response of cells caused by lack of aminoacetylated tRNAs. Experimentally, this response occurs due to the lack of amino acids in the environment and the limitation of tRNA aminoacylation even in the presence of the corresponding amino acids in the cell. Many features of this response indicate its dependence on the accumulation of ppGpp molecules. There is a correlation between the growth rate of actinomycetes and biosynthesis of their secondary metabolites. Introduction of additional relA gene copies of ppGpp synthetase can affect the production of antibiotics in streptomycetes. The article presents the authors' own experimental data, dedicated to the influence of heterologous relA gene expression in Streptomyces nogalater cells.
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Transcriptional regulators of GntR family in Streptomyces coelicolor A3(2): analysis in silico and in vivo of YtrA subfamily. Folia Microbiol (Praha) 2015; 61:209-20. [PMID: 26433722 DOI: 10.1007/s12223-015-0426-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 09/27/2015] [Indexed: 01/27/2023]
Abstract
Transcriptional factors of the GntR family regulate numerous physiological and morphological processes in response to the nutrient state of bacterial cells. The number of GntR transcriptional factors in genomes of soil-dwelling actinomycetes is one of the highest among bacteria, reflecting both the large size of their chromosomes and the complex ecological niche that they occupy. However, very little is known about the roles of GntRs in actinomycete biology. Here, we analyzed the genome of model actinomycete, Streptomyces coelicolor A3(2), in an attempt to gain new insights into the function of GntR family. All 56 GntR proteins of M145 strain were classified into FadR, HutC, MocR, YtrA, and DevA subfamilies according to their secondary structure. We then checked for the presence of GntR orthologs in six other sequenced Streptomyces and one Kitasatospora genomes, revealing that 12 GntRs were conserved in all analyzed strains. Genomic analysis of the less studied YtrA type regulators revealed 160 sequences present in 88 members of Coriobacteridae, Rubrobacteridae, and Actinobacteridae subclasses. These proteins form seven dense clusters on the consensus phylogenetic tree and their genes are usually co-located with the genes for transport proteins. Probable operator sites were identified for orthologous groups of Sco0823 and Sco3812 proteins. All S. coelicolor YtrA-like regulatory genes (SCO0823, SCO1728, SCO3812) were analyzed at transcriptional level, knocked out, and introduced on moderate copy number plasmid in M145 strain. Also, gene SCO0824, a part of putative SCO0823 operon, was studied. Results of these experiments are discussed here.
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Genes for biosynthesis of butenolide-like signalling molecules in Streptomyces ghanaensis, their role in moenomycin production. RUSS J GENET+ 2014; 50:563-568. [PMID: 25624748 DOI: 10.1134/s1022795414060076] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Moenomycins (Mm) - phosphoglycolipid compounds produced by Streptomyces ghanaensis ATCC14672 - are considered a promising model for development of novel class of antibiotics. In this regard it is important to generate Mm overproducing strains which would be a basis for economically justified production of this antibiotic. In this work a set of genes for synthesis and reception of low-molecular weight signaling molecules (LSM) in ATCC14672 were described and their significance for Mm production was studied. The ATCC14672 genome carries structural and regulatory genes for production of LSMs of avenolide and γ-butyrolactone families. Additional copies of LSM biosynthetic genes ssfg_07848 and ssfg_07725 did not alter the Mm production level. ATCC14672 LSMs are not capable of restoring the sporulation of butyrolactone-nonproducing mutant of S. griseus. Likewise, while the heterologous host S. lividans 1326 produced Mm, its mutant M707 (deficient in the butyrolactone synthase gene scbA) did not. Thus, while the natural level of LSMs production by ATCC14672 does not limit Mm synthesis, the former is essential for the synthesis of moenomycins.
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[Genes for biosynthesis of butenolide-like signalling molecules in Streptomyces ghanaensis, their role in moenomycin production]. GENETIKA 2014; 50:645-651. [PMID: 25715454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Moenomycins (Mm)--phosphoglycolipid compounds produced by Streptomyces ghanaensis ATCC14672--are considered a promising model for development of novel-class of antibiotics. In this regard it is important to generate Mm overproducing strains which would be a basis for economically justified production of this antibiotic. In this work a set of genes for synthesis and reception of low-molecularweight signaling molecules (LSM) in ATCC14672 were described and their significance for Mm production was studied. The ATCC 14672 genome carries structural and regulatory genes for production of LSMs of avenolide and γ-butyrolacone families. Additional copies of LSM biosynthetic genes ssfg_07848 and ssfg_07725 did not alter the Mm production level. ATCC14672 LSMs are not capable of restoring the sporulation of butyrolactone-nonpro-ucing mutant ofS . griseus. Likewise, while the heterologous host S. lividans 1326 produced Mm, its mutant M707 (deficient in the butyrolactone synthase gene scbA) did not. Thus, while the natural level of LSMs pro-uction by ATCC 14672 does not limit Mm synthesis, the former is essential for the synthesis of moenomycins.
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Generation and study of the strains of streptomycetes - heterologous hosts for production of moenomycin. RUSS J GENET+ 2014; 50:360-365. [PMID: 25624747 PMCID: PMC4303909 DOI: 10.1134/s1022795414040085] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Moenomycins (Mm) are family of phosphoglycolipid natural products that is considered a blueprint to develop new class of antibiotics. The natural Mm producer, Streptomyces ghanaensis (ATCC14672), produces very low amounts of moenomycin, fueling the investigations on genetic approaches to improve its titers. Heterologous expression of moenomycin biosynthesis gene cluster (moe) would be one of the ways to reach this goal. Here we report the generation of a number of novel heterologous streptomycete hosts producing nosokomycin A2 (one of the members of Mm family), and determine their potential for the antibiotic production. The rpoB point mutation in the model strain of Streptomyces genetics, S. coelicolor (strain M1152) significantly improved nosokomycin A2 production compared to parental strains (M145 and M512), while double rpoBrpsL mutation in the same species (strain M1154) decreased it. Our results point to the previously unanticipated epistatic interactions between mutations that individually are known to be highly beneficial for antibiotic production. We also showed here for the first time that facultative chemolitotrophic streptomycete S. thermospinosisporus and chloramphenicol producer S. venezuelae can be used as the hosts for moe genes.
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Characterization of the Streptomyces globisporus 1912 lnd-cluster region containing the lndY, lndYR, lndW2, and lndW genes. CYTOL GENET+ 2013. [DOI: 10.3103/s0095452713010106] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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[Characterization of Streptomyces globisporus 1912 lnd-cluster region containing lndY, lndYR, lndW2 and lndW genes]. TSITOLOGIIA I GENETIKA 2013; 47:11-16. [PMID: 23427607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Streptomyces globisporus 1912 lnd-cluster region which flanks structural lndZ5-lndZ6 genes contains four open reading frames lndW, lndW2, lndYR and lndY. The latter one encodes putative proteinase which can regulate landomycin production and morphogenesis like LndYR. However, results of lndY overexpression and gene knockout showed that lndY did not participate in regulation of landomycin production and morphogenesis of Streptomyces globisporus 1912. Using transcriptional fusion of promoter lndWp to catechol dioxygenase reporter gene xylE the temporal character of interaction of promoter lndWp and repressor LndYR was studied.
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Properties of lanK-based regulatory circuit involved in landomycin biosynthesis in Streptomyces cyanogenus S136. RUSS J GENET+ 2010. [DOI: 10.1134/s1022795410050030] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Properties of lanK-based regulatory circuit involved in landomycin biosynthesis in Streptomyces cyanogenus S136. GENETIKA 2010; 46:604-609. [PMID: 20583594 PMCID: PMC2905788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
LanK is TetR-like regulatory protein recently shown to regulate the export and glycosylation of landomycins in Streptomyces cyanogenus S136. Here, several properties of the lanK-mediated regulation were deciphered. LanK seems to function as oligomer as evident from experiments in vitro. In vivo, it is able to recognize various landomycins with altered aglycon structure and the minimal concentration of landomycin A sensed by LanK lies in low nanomolar range. Coexpression studies showed that the positive regulatory gene lanI upregulates lanK-dependent lan genes once the negative LanK-regulation is cancelled. Gene lanK can be useful for the construction of biosensor strains for sensitive and specific identification of producers of landomycin-like molecules with long glycosidic chains.
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Chemistry and biology of landomycins, an expanding family of polyketide natural products. Mini Rev Med Chem 2009; 9:1040-51. [PMID: 19689401 DOI: 10.2174/138955709788922593] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This review covers existing literature (from 1990 to 2008) on landomycins (LS), a family of glycosylated angucyclines, with an emphasis on the bioactivity scope of landomycin (La)-like structures accessible via biocombinatorial manipulations. Some LS display strong antitumor activity and have inspired several chemical studies focused mainly on their unusual deoxysugar chains. A decade of genetic studies on La-producing bacteria has provided many novel molecules with altered structure and activity. A complex nonlinear correlation between the length of the carbohydrate tail of LS and their antitumor activity has also been revealed. It implies that simpler LS than the largest member of the family, LaA, are still potential drug leads. Combinatorial biosynthesis appears to be a powerful tool to search the chemical space around the La scaffold.
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Heterologous cross-expression of oxygenase and glycosyltransferase genes in streptomycetes, producing angucyclic antibiotics. CYTOL GENET+ 2009. [DOI: 10.3103/s0095452709030098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Heterologous cross-expression of oxygenase and glycosyltransferase genes in streptomycetes, producing angucyclic antibiotics. TSITOLOGIIA I GENETIKA 2009; 43:55-62. [PMID: 19938638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The heterologous expression of oxygenase genes urdM, ovmOIII, lanM2, IndZ5 and glycosyltransferase gene urdGT2 in different angucycline producers of genus Streptomyces has been carried out. The introduction of genes urdM, lanM2 and urdGT2 results in the accumulation of new glycosylated compounds in several strains under investigation. A number of processed recombinant strains display streptomycin sensitivity and decrease in total antibacterial activity. The obtained data is an evidence of changes in antibiotics production, resulting from post-polyketide synthase (post-PKS) tailoring gene expression across streptomycete strains. Our study demonstrates the potential of post-PKS tailoring genes for generation of novel bioactive metabolites.
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Proton-dependent transporter gene lndJ confers resistance to landomycin E in Streptomyces globisporus. GENETIKA 2007; 43:1032-1037. [PMID: 17958301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Sequence analysis of 2 kb BamHI-SmaI fragment of landomycin E (LaE) gene cluster in S. globisporus 1912 revealed one complete ORF marked as lndJ. Analysis of putative LndJ aminoacid sequence allowed us to suppose that it is proton-dependent antiporter which could be involved in resistance to LaE in the producing strain. Although disruption of lndJ had no significant influence on LaE production and resistance, it's overexpression in wild type and LaE overproducing strains led to qualitative changes in landomycins biosynthesis and increased resistance to LaE. These data support the hypothesis about involvement of lndJ gene in landomycins export.
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Proton-dependent transporter gene lndJ confers resistance to landomycin E in Streptomyces globisporus 1912. RUSS J GENET+ 2007. [DOI: 10.1134/s1022795407080030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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IncP plasmids are most effective in mediating conjugation between Escherichia coli and streptomycetes. RUSS J GENET+ 2006. [DOI: 10.1134/s1022795406050036] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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IncP plasmids are most effective in mediating conjugation between Escherichia coli and streptomycetes. GENETIKA 2006; 42:595-601. [PMID: 16808239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Mobilizable shuttle plasmids containing the origin of transfer (oriT) region of plasmid F (IncFI), ColIb-P9 (IncI1), and RP4/RP1 (IncPalpha) were constructed to test the ability of the cognate conjugation system to mediate gene transfer from Escherichia coli to Streptomyces. The conjugative system of the IncPalpha plasmids was shown to be most effective in conjugative transfer, giving peak values of (2.7 +/- 0.2) x 10(-2) S. lividans TK24 exconjugants per recipient cell. To assess whether the mating-pair formation system or the DNA-processing apparatus of the IncPalpha plasmids is crucial in conjugative transfer, an assay with an IncQ-based mobilizable plasmid (RSF1010) specifying its own DNA-processing system was developed. Only the IncPalpha plasmid mobilized the construct to S. lividans indicating that the mating-pair formation system is primarly responsible for the promiscuous transfer of the plasmids between E. coli and Streptomyces. Dynamic of conjugative transfer from E. coli to S. lividans was investigated and exconjugants starting from the first hour of mating were obtained.
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DNA-binding activity of LndI protein and temporal expression of the gene that upregulates landomycin E production in Streptomyces globisporus 1912. Microbiology (Reading) 2005; 151:281-290. [PMID: 15632445 DOI: 10.1099/mic.0.27244-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The gene lndI is involved in the pathway-specific positive regulation of biosynthesis of the antitumour polyketide landomycin E in Streptomyces globisporus 1912. LndI was overexpressed in Escherichia coli as a protein C-terminally fused to the intein-chitin-binding-domain tag and purified in a one-step column procedure. Results of in vivo LndI titration, DNA gel mobility-shift assays and promoter-probing experiments indicate that LndI is an autoregulatory DNA-binding protein that binds to its own gene promoter and to the promoter of the structural gene lndE. Enhanced green fluorescent protein was used as a reporter to study the temporal and spatial pattern of lndI transcription. Expression of lndI started before cells entered mid-exponential phase and peak expression coincided with maximal accumulation of landomycin E and biomass. In solid-phase analysis, lndI expression was evident in substrate mycelia but was absent from aerial hyphae and spores.
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Abstract
Rhodinosyl transferase gene lndGT4, governing the conversion of the disaccharide oligoketide ('polyketide') landomycin D into a trisaccharide derivative landomycin E, was deleted in Streptomyces globisporus 1912 genome. Possible resistance mechanisms that protect the resulting landomycin D-producing mutant strain S. globisporus LD3 against the toxic action of landomycins were determined.
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Targeted disruption ofStreptomyces globisporus lndF andlndL cyclase genes involved in landomycin E biosynthesis. Folia Microbiol (Praha) 2003; 48:484-8. [PMID: 14533479 DOI: 10.1007/bf02931329] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Streptomyces globisporus strains with knockouts in lndF and lndL genes, previously identified as possibly encoding cyclases governing cyclization of the nascent oligoketide ('polyketide') chain during the biosynthesis of the antitumor angucycline landomycin E, were prepared. On combining the results of sequence analysis and HPLC of extracts from mutant strains, lndL was suggested to control the first cyclization-aromatization event and lndF to be responsible for the 3rd-4th ring formation.
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Production of landomycins in Streptomyces globisporus 1912 and S cyanogenus S136 is regulated by genes encoding putative transcriptional activators. FEMS Microbiol Lett 2003; 222:149-53. [PMID: 12757959 DOI: 10.1016/s0378-1097(03)00258-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The regulatory genes lanI and lndI have been cloned from the landomycin A (LaA) producer Streptomyces cyanogenus S136 and from the landomycin E (LaE) producer Streptomyces globisporus 1912, respectively and both have been sequenced. A culture of S. globisporus I2-1 carrying a disrupted lndI gene did not produce LaE and other related intermediates. Complementation of S. globisporus I2-1 with either the lndI or lanI gene reconstituted LaE production indicating that LanI and LndI are involved in activation of structural genes in the respective clusters. Structural features of these regulatory genes are discussed.
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Analysis of a kanamycin resistance gene (kmr) from Streptomyces kanamyceticus and a mutant with increased aminoglycoside resistance. J Basic Microbiol 2000; 38:231-9. [PMID: 9791946 DOI: 10.1002/(sici)1521-4028(199809)38:4<231::aid-jobm231>3.0.co;2-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Kanamycin resistance gene (kmr) from the overproducing mutant strain of Streptomyces kanamyceticus ISP1375 (strain 1) and from its gentamicin-resistant mutant were cloned into the high copy number vector pIJ702 and transformed into S. lividans 66. This gene provides resistance to kanamycin, gentamicin, sisomicin and tobramicin. The resistance of the transformed recipient strains was higher than the resistance level of the donor S. kanamyceticus 1. Sequencing of the kmr gene (EMBL Nucleotide Sequence Database accession no. Y15838 revealed 53.9% identity in 274 aa with the kgmB gene product (16S rRNA methylase) of S. tenebrarius. Hybridisation analysis using a 0.85 kb fragment carrying the kmr gene revealed that other gentamicin-resistant mutants of S. kanamyceticus 1 and unstable kanamycin-nonproducing mutant had a high level of kmr amplification. We found no homology between the kmr gene and the total DNA of the neomycin producer S. fradiae IFO3718; the sisomicin producer M. zionensis IFO14116 and the gentamicin producer M. purpurea ATCC15835.
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