PRODUCTION OK \ ITAMINH AM) OTIIIIU (iUOWTU FACrrollS 



195 



minor ninount. Tracos of coproporpliyriiis 

 I and 1 1 , of uroporphyrin T, and of ot her non- 

 itlcntiliiMl poi-phyrins wvw also n'lcascd in 

 \\\v nuxliuni. The total fr(>c porphyrin con- 

 tent in l)roths may roach, in som(> strains, 

 20 to 40 juii", ml. The mutants producing;" 

 j2;r(>at(>r amounts of porphyrins ^avv lower 

 yiokls of \itamin Hp.. than tiic |)arcnt strain. 

 Loss aerated cultures pi-oduced more por- 

 ])hyrins and less \'itamin Hi_> . The lack of 

 cobalt lowered porphyrin production. Added 

 5-anunolae\ulic acid (100 to 500 Mg/ml) in- 

 creased porphyrin production, but did not 

 exert any effect on vitamin Bio levels. Small 

 amounts of succinic and glyoxylic acids were 

 detected in suspensions of A''. )-ugosa incu- 

 bated with citrate under anaerobic condi- 

 tions. Since glyoxylic acid can be a precursor 

 of glycine, it was suggested that this reaction 

 might have some meaning in porphyrin bio- 

 synthesis by this strain. 



A detailed discussion on the effect of co- 

 t)alt concentration in the medium upon the 

 production of vitamin B12 is given in Chapter 

 8. Darken (1953) reviewed the production of 

 B12 by actinomycetes. 



Other Vitamins and Vitamin-like Ma- 

 terials 



Actinomycetes have also been found to 

 produce various other porphyrin-like (Cor- 

 tese) and iron-containing compounds, such as 

 grisein. They also have the capacity to pro- 

 duce other water-soluble vitamins, notably 

 coenzyme A, the pteroylglutamic acid de- 

 rivative that promotes the growth of certain 

 strains of Leuconostoc citrovorum. 



Little is known of the mechanisms in- 

 volved in the direct symbiosis of actino- 

 mycetes with insects, as in the case of the 

 nymph of the hemipterous insect Rhodmus 

 prolixus, the moulting and reproduction of 

 which depend upon its infection with N. 

 rhodnii. Brecher and Wigglesworth (1944) 

 isolated a culture of a nocardia regularly 



from this insect roared in the lai^oratory. 

 The microorganism is not transmitted 

 through the egg but is taken up by the young 

 nymph fi'om the environment, such as the 

 contaminated surface of the egg, and more 

 often perhai)s from the dry excreta of other 

 meml)(M-s of the species. Insects wore reared 

 free from the actinomycete l)y sterilizing the 

 surface of the (>gg and feeding with suitable 

 precautions. They grew and moulted nor- 

 mally until the 4th or 5th instar. Moulting 

 was then delayed or failed entirely in spite 

 of repeated feedings of blood. Very few in- 

 sects without the actinomycetes became 

 adult, and those few were almost certainly 

 incapable of reproduction. Normal growth 

 and moulting and egg production were re- 

 sumed when the insects were reinfected with 

 the organism. 



Little is also known of the role of the 

 streptomycete that is able to infect nema- 

 todes that grow in the cockroach (Hoffman). 



Other references in the literature concern 

 the formation by certain actinomycetes of 

 substances that exert a stimulating effect 

 upon the growth of various organisms. It is 

 sufficient to mention the work of Rehm on 

 the presence in the mycelium of cultures of 

 the *S'. alhus group of substances that stimu- 

 late the growth of the fungus Aspergillus 

 niger. 



GroMth Stimulating Effect of Antibi- 

 otics 



The highly significant practical results ob- 

 tained by the stimulating effects of antibi- 

 otics upon animal growth could not all be 

 explained by the action of known vitamins. 

 Moore et al. first observed, in 1946, this 

 effect for an actinomycete antibiotic, namely 

 stroptothricin. At the present time, large 

 ciuantities of the tetracyclines and strepto- 

 mycin are employed in the feeding of non- 

 herbivorous animals. Some of these growth 

 factors are still unidentified (Fitz et al. 1956). 



An early review of the effect of antibiotics 



