NUTRITION OF MICRO-ORGANISMS 



Antibacterial Action of p-Aminobenzoic Acid 



The growth of certain gram-negative organisms e.g. E. coli was 

 inhibited by a i in 150 solution of sodium ^-aminobenzoate, and the 

 growth of M. tuberculosis by a i in 1000 solution. Gram-positive 

 organisms were not affected by a i in 100 solution. ^^<* The severity 

 of experimental tuberculosis in guinea-pigs was mitigated by the oral 

 administration of about 100 mg. daily of j5)-aminobenzoic acid, and the 

 survival time of the animals was increased, but neither the develop- 

 ment of the infection nor the eventual fatal outcome was prevented.^^^ 

 On the other hand, ^-aminobenzoic acid accelerated the onset of ex- 

 perimental typhoid in mice and shortened the survival time.^^'' 



Moulds and Yeasts 



_/)-Aminobenzoic acid was essential for the growth of an X-ray 

 mutant of Neurospora crassa ^^ and of Rhodotorula aurantiaca}'^ It 

 accelerated the grow^th of Penicillium roquefortii and Byssochlamys 

 fulva but inhibited the growth of Aspergillus niger}^ It neutralised 

 the inhibitory action of sulphanilamide on Penicillium digitatum, 

 Fusarium coeruleum and Botrytis allii}^ 



One mutant of N. crassa actually required sulphonamides for 

 growth and was inhibited by ^-aminobenzoic acid ; the inhibition 

 was completely antagonised by sulphonamides.^^" A double mutant, 

 carrying the gene for sulphonamide requirement and a gene for 

 failure to synthesise _/)-aminobenzoic acid, required both substances 

 for growth. 



Other Micro-organisms 



The growth of Strigomonas oncopelti was inhibited by sulphanil- 

 amide and the inhibition was counteracted by ;;!)-aminobenzoic acid in 

 concentrations 264,000 times that of the sulphanilamide.^^ ^-Amino- 

 benzoic acid had no effect on experimental toxoplasmosis in mice, but 

 it nullified the protection afforded by sulphathiazole.^i Clinical im- 

 provement in cases of amoebiasis followed the administration of 

 ^-aminobenzoic acid.^^" 



Viruses and Rickettsiae 



_/)-Aminobenzoic acid was remarkably effective in murine typhus 

 infection in mice when added to the food in a concentration of 3 %.^^ 

 It was also effective against some rickettsial infections of chick embryos 

 when injected into the yolk-sac and was twice as effective against 

 Rocky Mountain spotted iever as against typhus, but it had no effect 



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