The Genus Actinoplanes and Related Genera
Sporeforming actinomycetes related to the genus Actinoplanes are combined at present under the suprageneric group named “actinoplanetes” (Goodfellow, 1989 ). Originally, the term actinoplanetes was used ecologically to describe the strains of Actinoplanes
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The Genus Actinoplanes and Related Genera GERNOT VOBIS
Sporeforming actinomycetes related to the genus Actinoplanes are combined at present under the suprageneric group named “actinoplanetes” (Goodfellow, 1989). Originally, the term actinoplanetes was used ecologically to describe the strains of Actinoplanes and a small number of their relatives (Nonomura and Takagi, 1977). The members of the genus Actinoplanes all produce sporangia that release actively swimming spores. Later, the term actinoplanetes was expanded to encompass also the five genera Amorphosporangium, Ampullariella, Pilimelia, Dactylosporangium, and Micromonospora, which all have a common cell wall chemotype containing meso- and/or 3-hydroxy diaminopimelic acid and glycine in combination with xylose and arabinose as the characteristic sugars in the hydrolysates of whole organisms (Goodfellow and Cross, 1984). The GC content of their DNA is in general 71–73 mol% (Vobis, 1989a), but recent studies have expanded the range to 67–76 mol% (Kothe, 1987). All genera of the actinoplanetes studied so far belong to one RNA homology cluster (Stackebrandt and Woese, 1981), excluding the sporangiate genera Streptosporangium, Spirillospora, Planomonospora, and Planobispora, which were classified for a long time within one family together with Actinoplanes (Bland and Couch, 1981). The genera excluded were placed temporarily into a suprageneric group called the “maduromycetes” (Goodfellow, 1989). According to Goodfellow et al. (1990) and Kothe (1987), the members of the actinoplanetes can now be harbored taxonomically in the newly defined family Micromonosporaceae, and those of the maduromycetes belong in the family Streptosporangiaceae (see this Volume). The genus Actinoplanes was first described by Couch (1950), who called attention to its close similarities in colonial characteristics to the genus Micromonospora (Ø rskov, 1923), which produces single nonmotile spores. Our knowledge of the sporangiate members was extended by subsequent descriptions of further genera: Ampullariella and Amorphosporangium (Couch, 1963), Pilimelia (Kane, 1966), and Dactylosporangium (Thiemann et al., 1967). In recent years, two new genera have been added: Glycomyces (Labeda et al., 1985) and Catellatospora (Asano and Kawamoto, 1986). Both genera form nonmotile spores in chains. Although their chemotaxonomic features suggest convincing arguments for placing them into the actinoplanetes group, their phylogenetic relationships still need to be investigated (E. Stackebrandt, personal communication).
This chapter was taken unchanged from the second edition.
Ecophysiology Without applying selective procedures, it is difficult to isolate the members of Actinoplanes and related genera from soil or other natural substrates. Although they are mesophilic and aerobic organisms, the growth rate of their colonies is often very slow, and on routine isolation plates, the fast-growing streptomycetes can overrun them before they have dev
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