148 BACTERIOLOGICAL CHEMISTRY 



aa plant hormones it was expected that p-naphthyl- 



/ Y^l CH =CH.COOH, 

 acrylic acid, would inhibit 



the growth of E. coli and that the effect would be reversed 

 by tryptophane. Inhibition is brought about by a 

 concentration of 0-0002 M p-naphthyl-1 -acrylic acid and 

 is reversed by 0-0002 to 0-00004 M tryptophane. Styryl- 



acetic acid, ^ ^CH^CH.CHg.CGOH, and cinnamic 



acid, <^ ^CH=CH.COOH, have similar but much 



weaker effects, whilst dihydro -cinnamic acid, benzoic 

 acid and fumaric acid, COOH.CH=CH.COOH, have no 

 such effect. 



Pantothenic acid is an essential metabolite for many 

 organisms and it has been shown that the growth of such 

 organisms is inhibited by the addition of pantoyltaurine, 



CHaX 



CH3— C.CHOH.CG.NH.CHa.CHa.SOaH, the Sulphonic 



CH2OH / 



acid analogue of pantothenic acid. For Str. 'pyogenes 

 about 500 times as much pantoyltaurine as there is 

 pantothenic acid present is required to cause inhibition. 

 The addition of pantothenic acid reverses the effect. 



Pantoyltauramide, CHgX 



•^ CH3— C.CHOH.CO.NH.CHj.CHa.SOa.NHj, 



CH2OH / 



has a similar effect. Pantoyltaurine can also inhibit the 

 growth of yeast. Mixtures of taurine, NHg.CHg.CHa. 

 SO3H, and ay-dihydroxy- p p-dimethyl-butyrolactone, 



CH3\ 



CH3--C.CHOH.CO, 



CHj/ or the compounds alone had no 



inhibitory effect on L. arahinosus whicli is inhibited by 

 pantoyltaurine. N-])antoyl- p-aminoetliyl tliiol, 



