PANTOTHENIC ACID 



14. PANTOTHENIC ACID IN THE NUTRITION 

 OF 2V1ICRO-ORGANISMS 



Bacteria 



As already stated (see page 360), pantothenic acid is essential for 

 the growth of Streptococcus lactis, Bacillus brassicae, Propionihacterium 

 pentosaceum, Lactobacillus helveticus, L. arabinosus and Proteus 

 morganii ; the last three organisms have been used for the micro- 

 biological assay of pantothenic acid. It is also essential for the 

 growth of Streptococcus haemolyticus and Diplococcus pneumoniae ; ^ of 

 Clostridium tetani ; ^ of Clostridium welchii ; ^ of " exacting " strains 

 of Corynebacterium diphtheriae * (other strains do not require panto- 

 thenic acid if /3-alanine is available) ; of some species of Pasteurella ^ 

 and Brucella ; ^ of Streptobacterium plantarum ; ^ of five species of 

 Propionibacterium ; ^ of three strains of Shigella paradysenteriae ; ^ 

 and of a mmiber of species of lactic acid bacteria. ^^ Clostridium botu- 

 linum required biotin, aneurine and choline, but pantothenic acid could 

 apparently substitute for aneurine and choline. ^^ 



The amounts of pantothenic acid in the cells of five bacteria that 

 did not require an extra-cellular source of pantothenic acid, namely, 

 Aerobacter aerogenes, Serratia marcescens, Pseudomonas fluorescens, 

 Proteus vulgaris and Clostridium butylicum were estimated by H. 

 Mcllwain ^^ at 24,000 and 96,000 molecules per cell and the rate of 

 synthesis at 5 to 40 molecules per cell per second. 



Escherichia coli synthesised pantothenic acid at the rate of 50 

 molecules per cell per second in the absence of j3-alanine and at ten 

 times this rate when /3-alanine was present. ^^ Pseudomonas aeruginosa 

 synthesised it at the rate of 9 and 30 molecules per cell per second in 

 the absence and presence respectively of pantoic acid.^ 



Pantothenic acid was inactivated (see below) by Streptococcus 

 haemolyticus (non-proliferating) at a rate equivalent to 23 to 41 mole- 

 cules per cell per second,^* and the rate was not appreciably altered 

 when the conditions were varied. Pantothenic acid was not synthe- 

 sised by this organism and both growth and pantothenic acid meta- 

 bolism were inhibited to the same extent by pantoyltaurine and 

 similar antagonists (see below). Pantothenic acid was metabolised by 

 Proteus morganii at a velocity ranging from 25 to 120 molecules per 

 cell per second. 



These reactions are therefore of approximately the same order, 

 falling into the class termed by Mcllwain m/xmol. order reactions. 

 The significance of this has already been discussed (page 284). 



According to G. M. Hills, ^^ the oxygen uptake of a pantothenic 

 acid-deficient culture of Proteus morganii was increased seven-fold by 

 the addition of pantothenic acid. The most important substrate 



380 



