ORDER MYXOBACTERIALES 1009 



bacterial colonies developed around the inocula and were purified by transfer to fresh 

 cellulose plates. 



Beebe reported a modified Krzemieniewski technic to be satisfactory. Fruiting 

 bodies that had developed on sterilized rabbit dung were transferred to bacterial 

 suspension agar plates. Associated bacteria failed to grow well, but myxobacteria 

 developed rapidly. 



The species of the genera Cytophaga and Sporocytophaga require special technics 

 (Stanier, Bact. Rev., 6, 1942, 143). The soil forms which decompose cellulose may 

 be enriched with a medium consisting of cellulose (usually in the form of filter paper) 

 and a neutral or slightly alkaline mineral base containing either ammonium or nitrate 

 salts as nitrogen source. For certain species chitin may be substituted for cellulose. 

 Pure cultures may be secured by use of soft agar (1 per cent or less) with finely divided 

 cellulose or with cellulose dextrins (Fuller and Norman, Jour. Bact., 46, 1943, 281). 



Cultivation of organisms. Pure cultures of many species have been grown upon 

 various media and substrates. Sterilized dung, dung decoction agar, nutrient agar, 

 potato and potato agar, sterilized lichens, etc. have all been used. Little study 

 has been made of the food requirements. Recent evidence indicates the utilization 

 of some of the more complex carbohydrates. Im.senecki and Solntzeva (Microbiology, 

 Moscow, 6, 1937, 3) reported the growth of certain species on cellulose with partial 

 decomposition of that compound. Mishustin (Microbiology, Moscow, 7, 1938, 427) 

 isolated five species of cellulose-decomposing myxobacteria, cultivating them on a 

 mineral salt-silica gel medium to which filter paper had been added as a source of 

 carbon. Krzemieniewska (Acta. Soc. Bot. Polon., 7, 1930, 507) grew species of the 

 Cytophagaceae on cellophane, while Stapp and Bortels (Cent. f. Bakt., II Abt., 90, 

 1934, 28) record the growth of other members of the same family on media containing 

 such carbon sources as mannitol, glucose, sucrose, dextrin, cellotriose and cellobiose. 

 Inorganic nitrogen sources compared favorably with organic, in some cases appearing 

 to be preferable. Stanier (Jour. Bact., 40, 1940, 623) observed peptone and yeast 

 extract to be the only suitable nitrogen sources for the Cytophagaceae, inorganic salts 

 and amino acids failing in this respect. Agar and cellulose were decomposed, while 

 chitin and starch were not utilized. Johnson (Jour. Bact., 24, 1932, 335) and Benton 

 (Jour. Bact., 29, 1935, 449) both reported chitinovorous myxobacteria. Beebe (Iowa 

 State Coll. Jour. Sci., 15, 1941, 319 and 17, 1943, 227) claimed growth of species of 

 Polyangium, Podangium, Chondrococcus and Myxococcus on 1.5 per cent agar with no 

 other nutrients added. Peptone appeared to aid development, while the addition 

 of beef extract had no favorable effect. Moderate growth occurred on a mineral salt- 

 agar medium without the addition of carbon or nitrogen sources. Growth was stimu- 

 lated by the addition of various complex carbohydrates including cellulose and starch, 

 the latter being hydrolyzed; complete inhibition resulted with pentoses and hexoses. 

 Best growth was reported on a medium composed of dried bacterial cells suspended in 



1.5 per cent agar. The suspended cells were lysed by the myxobacteria. 



The Krzemieniewskis (Acta Soc. Bot. Pol., 5, 1927, 102) showed that the optimum 

 hydrogen ion concentrations for growth of different species were found between pH 



3.6 and 8.0. Beebe (1941, loc. cit.) reported no growth of anj^ species below pH 6.0, 

 while moderate development was noted up to pH 9.0. 



Habitat and distribution. Many species have been described from dung. The 

 work of the Krzemieniewskis (Acta Soc. Bot. Pol., 5, 1927, 102), Mishustin (Micro- 

 biology, Moscow, 7, 1938, 427), Imsenecki and Solntzeva {loc. cit.) and others seems 

 to indicate that they occur commonly in soils, particularly soils under cultivation 

 or high in organic materials. Different species appear to be characteristic of various 



