M(>Hi'ii()i,()( ;^ . ('^ 'l'()l,()(;^■, and i,ii-i: ('^('ij:s 



85 



orijiiinal hyphar. This lUMimcr ol' sporulat ion 

 is more characttMistic ol' I lie liciuis Xocdnh'd. 



Drcchsicr (Icsci'ihcd tliicc tyjx's of sporu- 

 lat ion ill a ii;roup ot' (aillui'i's represent iiifj; 

 piiinaril>' the j>;(MU1s Stn ploDijia s: (;i) t I'lie 

 Ira.uineutatioii, [\i) the (h)ul)iini; of the cell 

 wall, {v) contractions similar to s(>«i;menta- 

 tion. DiU'he also reeoj'-nized three types of 

 spores: (a) rej^ular and invfiiuiar aithi-o- 

 spores, (h) microarthrospores, prodiiccMl in 

 the substrate myeeliiim, and (e) endospoi-es, 

 pi'odueod in the aei'ial mycelium. True 

 conidia, or "fragmentation" spoics, aic pro- 

 diiceti only in the aerial mycelium, whei'eas 

 the substrate mycelium gives rise to chlamy- 

 (K)spores or to arthrosporcs formed l)y the 

 concentration of the plasma in the mycelium. 



Sporulation among the Alicromonospora is 

 distinct from that of the other genera of 

 actinomj'cetes. The mj'celium is monopodi- 

 ally branched. The conidia are formed on 

 special branches, which are straight and 

 short (5-10 n) and which frec^uently give 

 rise to other branches, thus forming struc- 

 tures similar to bunches of grapes. Each 

 branch bears at the end a single spore, pro- 

 duced by the splitting off of the tip of the 

 hypha. Sporulation occurs most abundantly 

 on synthetic media. Recent studies on spor- 

 ulation of actinomycetes have been made 

 by Bisset (1957). 



(Spores 



The spores of actinomycetes are spherical 

 (0.3-0.8 ju for Strepfomyces and 1.0-1.3 fi for 

 Micromonospora) , oval, or cylindrical (0.8-1 

 by 0.7 fjL for Streptomyces and 1 .3-1.5 })y 1 .2 /x 

 iov Micromonospora) . The shape and size of 

 the spores are characteristic of the species. 

 The paired spores for Walsmania {Micro- 

 bispora) and Thermopolyspora are charac- 

 teristic for these genera. These spores are 

 reproductive V)odies, comparable to fungus 

 spores, rather than resistant bodies, as in the 

 case of bacterial spores. They are destroyed 

 ])V heat at 00 to r)5°C for 10 to 15 minutes. 



FiGi'RE 44. ChauLs of spores (Rei)roduced 

 from: Baldacci, E. et al. Giorn. Microbiol. 1: 521, 

 1956). 



The spores are only slightly more resistant 

 to heat than is the mycelium. 



A detailed study of the nature of th(! 

 spores of Streptomyces has been made by 

 Jensen (1931) and more recentlj^ by Flaig 

 et al. (1952, 1954). The latter suggested a 

 system of classification of this group of or- 

 ganisms on the basis of spore structure: 

 I. Spores long, oval-shaped 

 II. Spores round-shaped: 



1 . surface of spores rough : 



a. spiny surface 



b. hairy surface 



c. warty surface 



2. surface of spores smooth 



III. Shape of spores cylindrical or rec- 

 tangular. 



On the basis of electron microscopic stud- 

 ies, Flaig et al. concluded that these spores 

 are of endogenous origin. They considered 

 the segmentation spores to be produced in 

 the substrate mycelium and as exogenous in 

 natur(\ Bringmann came to the same con- 

 clusions. The ('()mi)osition of the medium 

 rarely has any effect on the form of the 

 spore, l^aldacci et ol. (1955, 1950) observed 



