COMPOSITION OF MICROBIAL AMINO ACID POOLS WS 
be composed largely of amino acids commonly found in protein. If one were to apply 
the criteria proposed by W1n1Tz (cf. this Symposium) for identification of amino acids 
as a qualification for consideration, this review would be confined to a discussion of 
no more than 10% of the reports which are cited. 
Bacteria 
The pool composition of a few gram-positive bacteria is presented in Table I. The 
lactic acid bacteria have been studied more intensively than any other bacterial 
group, largely through the efforts of CHEESEMAN, BERRIDGE, MATTICK and others 
at the University of Reading who have investigated the application of pool chromato- 
graphy asanaidin taxonomic studies (cf. refs. 13, 30-34, 62, 63, 119, 161). Borrazzi'7~*, 
originally a collaborator of the Reading group, also has presented results of a similar 
study. In many instances, a large number of strains of a given organism have been 
compared. These results have been averaged for inclusion in Table I. The observations 
of this group are atypical to the extent that many of the commonly encountered 
amino acids are not found on their chromatograms whereas a large number of un- 
knowns are reported. Cells were extracted with acetic acid, a method which appears 
to favor the demonstration of these components. This was useful for the purposes of 
their study since differences in distribution of unknowns has aided the separation of 
some species. However, results for the same organisms examined in different labora- 
tories using different growth media and extractants show a markedly different pattern 
of amino acids (e.g., Lactobacillus arabinosus and S. aureus). Such comparisons will 
be drawn repeatedly to illustrate a major conclusion of this survey, that microbial 
pools are subject to such wide variability depending on strain, cultural conditions, 
medium composition and age that comparisons appear to be valid only when all ex- 
perimental conditions are standardized. Therefore, for bacteria, and it will be seen 
later that the same is true also of yeasts and molds, it is not possible to speak of char- 
acteristic patterns of pool amino acids without specific description of all cultural 
conditions. 
Another example of the wide discrepancy in qualitative and quantitative pool 
composition is seen in the two studies on Bacillus subtilis (Table 1). It should be 
noted, however, that under closely controlled conditions the pool can have a strikingly 
stable composition. Figs. 1-4 illustrate results presented by the Reading group 
showing that chromatograms even of different strains of an organism are virtually 
superimposable. The study of PFENNIG!? also illustrates that major modifications in 
intracellular metabolism, as when a bacterial spore germinates to form a vegetative 
cell, are accompanied by profound, reproducible changes in pool composition, sug- 
gesting that the latter might be utilized to provide clues to the detailed metabolic 
changes. 
With the exception of the results reported by the Reading group, the data shown 
in Table I demonstrate that most investigators using two-dimensional paper chromato- 
graphy without recourse to adjuncts such as radioisotopes find that the pool consists 
largely of the amino acids present in protein. Pool constituents of unusual structure 
or interest such as peptides, D amino acids, etc., have been reported less frequently 
and will be considered separately below. 
References p. 105/108 
