C h a p t e 



Actinoplanaceae 



Substrate mycelium usually inconspicu- 

 ous, formed in water, on a variety of plant 

 and animal materials. Aerial mycelium 

 usually lacking; only certain species pro- 

 duce such mycelium, thus resembling 

 Streptomyces. Reproduction by spores formed 

 in sporangia. The spores in Actinoplanes 

 possess flagella and are motile. The spores 

 of Streptosporangium are without flagella 

 and are nonmotile. Many species produce 

 aerial spores. These organisms can be culti- 

 vated on a variety of artificial media; they 

 will then resemble in their growth other 

 actinomycetes. The family is widely dis- 

 tributed in soil and in fresh water. The 

 Actinoplanaceae can be classified as follows: 



1. Aerial mycelium usually not formed; 

 coiled conidiophores lacking; sporangio- 

 spores motile. 



Genus I. Actinoplanes 



II. Aerial mycelium abundant; coiled co- 

 nidiophores as well as sporangia an 1 

 formed in some species; sporangiospores 

 nonmotile. 



Genus II. Streptosporangium 



Genus iclinoplaiies Couch 



(Couch, J. N. J. Elisha Mitchell Sci. Soc. 

 66, 87, 1950; 71, 48, 1955. Trans. X. Y. 

 Acad. Sci. 16, 315, 1954). 



Occur on sterilized leaves in water, form- 

 ing a very inconspicuous mycelium which 

 branches throughout the leaf tissue. The 

 externa] hyphae are scattered or in tufts on 



the leaf surface and form a fringe around 

 the edge of the leaf. Aerial mycelium is 

 lacking or sparingly formed; usually pinkish 

 to reddish, sometimes hyaline; frequently 

 decolorizes the green leaf and gives it a 

 pinkish or reddish color. Hyphae slightly to 

 considerably branched, irregularly coiled, 

 twisted or straight, sparingly septate, 0.2 to 

 2.6 m in diameter. Sporangia usually abun- 

 dant on leaves, formed only when the leaf is 

 at or close to the surface of the water, i.e. 

 formed typically only in air, and appearing 

 black under the low power of the microscope, 

 owing to refraction; of varied sizes and 

 shapes. Spores in coils, nearly straight 

 chains, or irregularly arranged, in sporangia; 

 1 to 1.5 ju in diameter, globose or subglobose, 

 usually slightly angular, with one to several 

 shiny bodies, with several polar flagella, and 

 motile; germination by a minute germ tube 

 which branches to form a mycelium. Spo- 

 rangial wall evanescenl or persistent (Fig. 63). 

 The organisms form on various nutrient 

 agars a brilliantly colored, tough to pasty 

 growth. Surface very variable: smooth and 

 even with the agar or elevated bumpy, 

 convoluted, ridged, folded, cracked, etc., 

 usually moist and shiny, rarely pulverulent. 

 Hyphae of two more or less distinct forms, 

 the submerged and the surface hyphae, the 

 latter usually more or less vertical and in 

 some species forming a compact "palisade." 

 Sporangia abundant on souk 1 agars, usually 

 formed at the surface. Spores formed in 

 some species. ( )n certain agars, the mycelium 

 of some species breaks up, when crushed, 



310 



