NUTRITION OF MICRO-ORGANISMS 



although attempts have been made to use Streptococcus salivarius ^^ 

 and Staphylococcus aureus. ^^ Neisseria gonorrhaeae gave good growth 

 only in the presence of aneurine,^^ but a strain was described by 

 C. E. Lankford and P. K. Skeggs *° that failed to grow with aneurine, 

 and required the whole cocarboxylase molecule although, rather sur- 

 prisingly, aneurine monophosphate (see page 125) had 80 % of the 

 activity of cocarboxylase. Aneurine itself competitively inhibited the 

 utilisation of cocarboxylase by the organism. The cocarboxylase 

 strain gave rise to variants capable of synthesising cocarboxylase. 

 Aneurine was essential for Clostridium tetani *^ and CI. botulinum.^^ 



Kligler et al.^^ studied the effect of aneurine deficiency on a culture 

 of 5. aureus. They found that the particular strain failed to grow or 

 ferment glucose in the absence of nicotinic acid, but in the absence of 

 aneurine about 40 % of the glucose consumed was converted into 

 pyruvic acid and 60 % into lactic acid. When both vitamins were 

 present, 40 % was converted to acetic acid, 20 % to lactic acid and 

 only a trace to pyruvic acid, whence they concluded that aneurine 

 was acting as a catalyst for the oxidation of pyruvic acid and could 

 only do this when nicotinic acid was available. 



It is obvious therefore that, although most bacteria grow without 

 the addition of aneurine to the medium, aneurine (or cocarboxylase) is 

 necessary for the metabolism of these micro-organisms . H. Mcllwain ** 

 calculated that Aerobacter aerogenes contained 2200 molecules of aneu- 

 rine per cell and that the organism synthesised anemine at the rate of 

 one molecule per cell per second. With Serratia marcescens, Pseudo- 

 monas fluorescens, Proteus vulgaris and Clostridium hutylicum, the 

 corresponding values were : 5400, 5200, 4200 and 1900 ; 17, 2-8, o-8 and 

 1*5 respectively. The " turnover number " of yeast carboxylase was 

 calculated to be twenty-two molecules per molecule of enzyme per 

 second, that is, twenty- two molecules of pyruvic acid reacted with 

 one molecule of carboxylase per second. The rates of s3mthesis and 

 inactivation of aneurine indicated that these reactions belonged to 

 the group termed by Mcllwain reactions of mjLtmol. order, because 

 their speed is of the order of a few m/xmols. per gram of dry weight 

 per second ; they therefore differ from the ordinary reactions of the 

 bacterial cell, which ajre of /xmol. prder. The significance of this 

 distinction is discussed in the chapter on nicotinic acid (page 284). 



B. paraalvei grew well in a synthetic medium containing fifteen 

 to eighteen amino acids when aneurine was added, but only moder- 

 ately well in its absence. ^^ In the absence of aneurine, phenylalanine, 

 valine, isoleucine and cystine were essential for growth, but cystine 

 could be replaced by cysteine, glutathione, homocystine or homo- 

 cysteine, though not by methionine. The thiazole portion of aneurine, 

 though not the pyrimidine portion, was a satisfactory substitute for 



III 



