78 J. T. HOLDEN 
TABLE II 
AMINO ACID POOLS IN GRAM-NEGATIVE BACTERIA* 
Escherichia Pseudomonas Salmonella Red Sulfur 
Organism . ; . . 
= coli saccharophila bareilly Bacterium 

Ref. numbers 116 118 2 129 
Growth Medium** CS CS DO 
Age (h) 24 30 480 
Growth phase*** LE S S S 

Glutamic acid 
Aspartic acid 
Glutamine 
Asparagine 
Alanine 
Glycine 
Threonine 
Serine 
Lysine 
Arginine 
Histidine 
Leucines 
Valine 
Methionine 
Proline 
Hydroxyproline 
Tyrosine 
Phenylalanine 
Tryptophane 
y-Aminobutyric acid @ 
Cyst(e)ine 
Unknowns e@ 3 


* See footnote * Table I. 
** See footnote ** Table I. 
*** See footnote *** Table I. 
Following the report of TAyLor?!’§, the gram-negative bacteria were thought to 
lack an amino acid pool. The data in Table II demonstrate that this impression was 
in error. A large number of investigators subsequently have found a diversified pool 
in these organisms, especially in Escherichia coli. This discrepancy appears partly to 
have risen from the osmotic lability of the pool in gram-negative bacteria”, %8. In 
contrast to gram-positive bacteria and yeast which retain their pools during repeated 
washing with water or solutions of low osmotic strength, organisms such as E. coli 
rapidly lose the pool under these conditions. In addition, the native pools in freshly 
harvested gram-negative bacteria appear to be smaller than those found in gram- 
positive organisms making their detection more difficult. Gram-negative in contrast 
to gram-positive bacteria also are frequently grown in media lacking preformed amino 
acids and, therefore, do not have an opportunity to augment the pool by accumulation 
of extracellular amino acids. 
The assortment of amino acids found is usually as varied as that encountered in 
gram-positive bacteria. Generalizations regarding consistent differences between the 
two groups of bacteria are difficult to make. In contrast to the gram-positive bacteria, 
References p. 105/108 
