24 BULLETIN 782, U. S. DEPARTMENT OF AGRICULTURE. 
The table shows that only a few cultures were able to ferment 
mucic, tartaric, and glyceric acid, in which there is a secondary 
alcohol radical connecting a carboxyl with another alcohol radical, 
as in mucic COOH(CHOH) 4 COOH, tartaric COOH(CHOH) 2 COOH, 
and glyceric CH 2 OH(CHOH)COOH. It seems to be somewhat easier 
for this group of bacteria to obtain carbon from glyceric acid when a 
primary alcohol radical (CH 2 OH) replaced a secondary (CHOH). 
Only 7 cultures were able to ferment tartaric acid, while none of the 
68 cultures were able to utilize gly colic acid. Tartaric acid has a 
CHOH COOH 
structural formula | where an alcohol radical is linked 
CHOH COOH 
CH 2 OH 
to a carboxyl and another alcohol, while in glycolic | an alcohol 
COOH 
radical is merely linked to a carboxyl. This difference in manner in 
which the alcohol radical is linked to the carboxyl may make it 
possible for some bacteria to ferment tartaric acid. In malonic 
/COOH 
acid CH 2 two carboxyls are linked by a methyl group and it was 
\COOH 
found that 11 of the 68 cultures were able to obtain carbon from 
this source, while none of them were able to ferment oxalic acid 
COOH 
when 2 carboxyl groups are joined directly. In this case 
COOH 
it seems that the presence of the methyl group connecting the carboxyl 
group makes it possible for a few cultures to obtain carbon, probably 
from the methyl radical. Our results indicate that carbon is not 
obtained from the carboxyl group, since none of the cultures were 
able to utilize oxalic acid. This, however, may be due to the poison- 
ous character of the acid. Whether this nonferment ability of the 
exalate is due to the configuration of the molecule or to the poisonous 
character of the compound, it is interesting to note that the work of 
Doryland (5) confirms this result as he was unable to obtain fer- 
mentation of oxalate when used as the only source of carbon in a 
synthetic medium in which 225 different bacteria were studied. 
A large number of the cultures could utilize carbon from the 
sodium salt of formic acid. It is possible to consider the structure 
of this acid HO-C and it seems evident that the carbon can be 
\H 
obtained from the aldehyd radical. If the structure is taken as 
H-COOH the organism would have to obtain carbon from a carboxyl 
group, and if they are able to do this with formic acid they should be 
expected to ferment oxalic acid. 
