lilOCllliMlCAl. AC"n\ ITIICS 



165 



Tabi,e 42 



Cheiniciil chiuuns in (hr .'<i/nlhclir medium inoculated with S. crytlireus (C'oruin ct at.) 



Some very interesting observation.s on bio- 

 synthe.si.s of streptoinvein were recently re- 

 ported b}^ Hockenhuli (1958). This antibiotic 

 is regarded as a modified trisaccharide, the 

 components l)eing a substituted cyclohexitol, 

 a pre^■iousl3' unknown branch chain sugar, 

 streptose, and L-X-methyl glucosamine. The 

 carbon of the.se moieties was found })y ra- 

 dioactive tracer .studies to arise from gkico.se, 

 the principal carbohydrate source used in 

 the medium. The L-X-methyl glucosamine 

 could be directly as.similated into the mol- 

 ecule. The streptidine arose from carbon 

 dioxide, arginine being considered as an in- 

 termediate. The L-glucosamine moiety was 

 believed to arise as an inversion of the glu- 

 cose molecule bj' way of a cyclohexitol. 



Growth of the streptomycin-producing 

 organism takes place under conditions of 

 ample carbohydrate and restricted nitrogen 

 suppl.y, usually in the form of soj^a-bean 

 meal. A low inorganic phosphate le\'el and 

 high aeration l)ring about a "Pasteur effect," 

 restricting the formation of organic acids or 

 metabolism by way of the tricarboxylic acid 

 cycle mechani.'^m. This results in an accumu- 

 lation of phosphorjdated carlxjhydrate inter- 

 mediates and a locking up of inorganic phos- 

 phate, which can then be regenerated by 

 polymerization. Increase of phosphate causes 



yield to fall. Restriction of aeration l)rings 

 about the formation of lactic acid. 



Doskocil (1958) attempted to elucidate 

 biosynthesis of oxytetrac3dine by S. rimosus 

 in a medium consisting of glucose, starch, 

 corn-steep, (XH4)2S04 , CaCO, , and so- 

 dium chloride. Two distinct growth phases 

 were observed. In the first phase, glucose was 

 used up and maltose accumulated. Glucose 

 disappeared in 9 to 12 hours of cultivation. 

 This coincided with maximum respiration 

 and maximum le\-el of pyru^-ate. Interrup- 

 tion of the growth phase is accompanied by 

 fragmentation of mycelium and the begin- 

 ning of oxytetracycline production. During 

 growth the washed mycelium metabolized 

 only glucose; within six hours after the 

 depletion of gluco.se it acquired the ability 

 to utilize malto.se. The mycelium began to 

 grow again, with no parallel increase of res- 

 piration and pyruvate, but with rapid pro- 

 duction of oxytetracycline (1.8 to 2 mg/ml). 



On a medium with glucose and without 

 starch there was a continuous increa.se of 

 respiration and formation of pyruvate until 

 complete depletion of glucose; production 

 of oxytetracycline reached only 0.7 to 0.9 

 mg/ml. The washed mycelium utilized only 

 glucose, not maltose. The adaptation to mal- 

 to.se re([uires a period of .se\eral hours during 

 which the mj'celium does not grow and the 



