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Transfer of plasmid pTO1 from Escherichia coli to various representatives of the order Actinomycetales by intergeneric conjugation.

Plasmid pTO1 containing the oriT fragment from RK2, the Escherichia coli replication function from pBR322, and a DNA fragment of actinophage phi C31 with the attachment site was transferred from E. coli S17-1 to strains of the genera Actinomadura, Arthrobacter, Micromonospora, Nocardia, Rhodococcus, and to 16 strains of the genus Streptomyces. The frequency of conjugant formation was 1 x 10(-3)-1 x 10(-5) depending on the strain. Hybridization experiments demonstrated that plasmid pTO1 integrates into chromosomes of a number of the recipient strains examined.

Actinomycetales↗

Aerobic mineralization of vinyl chloride by a bacterium of the order Actinomycetales.

A gram-positive branched bacterium isolated from a trichloroethylene-degrading consortium mineralized vinyl chloride in growing cultures and cell suspensions. Greater than 67% of the [1,2-14C]vinyl chloride was mineralized to carbon dioxide, with approximately 10% of the radioactivity appearing in cell biomass and another 10% appearing in 14C-aqueous-phase products.

Actinomycetales↗

Motile nocardoid Actinomycetales.

The properties of 42 strains of nocardoid (nocardioform) bacteria were compared. The results indicate that the organism previously called Nocardia turbata does not belong to the genus Nocardia nor does it fit into any of the previously described genera.

Actinomycetales↗

Ultramicroscopic structure of Intrasporangium calvum (Actinomycetales).

The electron microscopic observation of vesicles formed by Intrasporangium calvum revealed that they do not contain spores. It thus seems that these vesicles should not be called sporangia. Isolation and study of three other strains of actinomycetes forming similar vesicles indicated that such structures can be formed by actinomycetes with very different properties. The taxonomic value of vesicle formation in actinomycetes is questioned.

Actinomycetales↗

Geodermatophilus, a new genus of the Dermatophilaceae (Actinomycetales).

Organisms having a complex life cycle similar to the animal pathogen Dermatophilus congolensis have been isolated from soils of the United States. The soil isolates grow readily on agar media producing a black, friable, or sooty colony; in broth, the isolates produce a thick sediment with a clear supernatant fluid and occasionally a black surface pellicle. The generic taxon Geodermatophilus is proposed for these soil isolates. Geodermatophilus differs morphologically from Dermatophilus in thallus shape, ensheathment, and branching, and physiologically in respect to blood hemolysis, casein hydrolysis, carbohydrate utilization, acid production, and media requirements. The type species proposed is G. obscurus. Three subspecies are recognized.

Actinomycetales↗

Poorly lytic bacteriophage from Dactylosporangium thailandensis (Actinomycetales).

Dactylosporangiophage A1 has a polygonal head (75 nm) with spherical capsomeres (3 nm) and a noncontractile tail (200 by 10 nm) with cross-striations which is terminated with at least three prongs which are used for attachment. It contains double-stranded deoxyribonucleic acid and produces very little lysis. Intracellular phage multiplication leads to the formation of crystalline aggregates of apparently complete virions. Plaques are formed only on certain substrains of Dactylosporangium thailandensis L1 and are always small (0.5 mm or less). They are clear on some substrains and turbid on others. Formation of plaques occurs only on one medium, Czapek agar with 0.2 to 0.4% yeast extract, 0.2% peptone, or a defined mixture of amino acids. Over 100 strains of bacteria, mainly actinomycetes, were screened in a futile attempt to find an indicator strain which is not a substrain of L1. The Dactylosporangium-phage system studied is considered to be a semiresistant carrier state.

Actinomycetales↗

Characterization of an effective actinorhizal microsymbiont, Frankia sp. AvcI1 (Actinomycetales).

The actinomycete, Frankia sp. AvcI1, isolated from root nodules of Alnus viridis ssp. crispa was grown in axenic culture and used to inoculate host seedlings. This bacterium has been shown to be an infective and effective nitrogen-fixing microsymbiont which can be distinguished from other frankiae, in vitro, on the basis of size, distinctive morphology, and growth characteristics. Cross-inoculation studies indicated that the host range of this symbiont encompasses all of the members of the genera Alnus, Myrica, and Comptonia tested. In all cases, the symbioses developed were effective in fixing atmospheric dinitrogen.

Actinomycetales↗

Characterization of an ineffective actinorhizal microsymbiont, Frankia sp. EuI1 (Actinomycetales).

The actinomycete, Frankia sp. EuI1, isolated from root nodules of Elaeagnus umbellata is an infective endophyte but which lacks the ability to form an effective nitrogen-fixing symbiosis with its host. This ineffective organism can be distinguished easily from other frankiae, in vitro, on the basis of size, morphology, and the elaboration of a diffusible pigment. Cross-inoculation studies indicated that the host range of this symbiont is narrow and probably restricted to the Elaeagnaceae. In all cases of nodulation the symbiosis never developed nitrogenase activity and the microsymbiont never produced endophytic vesicles within the infected host cells. Sporangia were produced in vivo and in vitro so the morphogenetic block is apparently restricted to vesicle formation.

Actinomycetales↗