GROWTH FACTORS lOl 



Adenine. — ^^ = c.XHa it has been shown that 



CH c- NH 



II !l \ 



II 11 CH 



II II // 



N-C-N 



adenine is a necessary constituent of media for the 

 groA\'th of Clostridium tetani. It can be replaced by 

 hypoxanthine. Very probably adenine is concerned in 

 the synthesis of nucleic acids and diphosphopyridine 

 nucleotide (see p. 202 et seq.). It has recently been shown 

 that adenine can inhibit the bacteriostatic action of some 

 of the sulphonamide drugs (see Chapter X). 



p-Alanine. — NH2.CH2.CH2.COOH. Saccharomyces 

 species and Corynebacterium diphtherice need ^-alanine 

 as a gro^Ai:h factor in s^Tithetic media. Since it forms a 

 part of the molecule of pantothenic acid it is probably 

 required for its synthesis. It is effective in promoting 

 the growth of C. diphtherice in concentrations of the 

 order of 1 /xg. per millilitre or less. (1 jLtg. =0-001 mg. 

 Sometimes the sjmibol y is used instead of 1 fig.) ^- 

 Alanine cannot be replaced by a-alanine. It may be 

 derived by many organisms from asparagine or aspartic 

 acid. 



2)-Aniinobenzoic aeid.— XHg^ ^COOH. It was 



shown by Woods and by Woods and Fildes in 1940 

 that p-aminobenzoic acid was the substance in yeast 

 extracts, peptone and other substances which inhibited 

 the bacteriostatic action of sulphonamide. drugs (see 

 Chapter X). It has since been shown to be a growth 

 factor for certain strains of Neurospora crassa, Aceto- 

 hacter suhoxydans (0-005 /xg/ml.), Clostridium aceto- 

 hutylicum (lxl0~® />tg./ml. in presence of l-5xl0~^ to 

 1-5 X 10"^ lig.jmX, of biotin) and 01. butyricum. 



