MICROORGANISMS IN DECOMPOSING OYSTERS 1 
By Albert C. Hunter and Bernard A. Linden, Microbiological Laboratory, 
Bureau of Chemistry, United States Department of Agriculture 2 
INTRODUCTION 
In a previous paper on the spoilage 
of oysters (6) [i the total aerobic counts 
of bacteria were given for shucked 
oysters in various stages of decomposi¬ 
tion. The results of that work indi¬ 
cated that there was no definite corre¬ 
lation between the total number of 
bacteria present and the stage of 
decomposition of the oysters. It was 
shown, however, that there was a 
definite correlation between the hydro¬ 
gen-ion concentration of the oyster 
liquor and the stage of spoilage. 
Realizing that the spoilage of oysters 
was probably due to the presence and 
development of bacteria of certain 
groups and that after identification of 
the groups responsible for the spoilage 
it might be possible to establish a 
correlation between a differential count 
of bacteria of certain types and the 
stage of decomposition, it was ap¬ 
parent that the next step in the inves¬ 
tigation was to collect and study, for 
identification, the bacteria present in 
decomposing oysters. This paper gives 
the results of a study of several hundred 
cultures collected from the dextrose- 
agar shake cultures and from the dex¬ 
trose-agar and wort-agar plates made 
in the course of the investigation 
already reported {6). 
NOMENCLATURE 
The nomenclature for bacteria, as 
presented in Bergey’s Manual of De¬ 
terminative Bacteriology (11) by a 
committee of the Society of American 
Bacteriologists, is used throughout this 
report. An attempt has been made 
to identity the organisms to species, 
but, owing to the meager and inade¬ 
quate descriptions often found in the 
literature and to the reactions of the 
peculiar atypical forms frequently iso¬ 
lated from material of the kind studied 
here, it has not been possible in all 
cases to definitely identify the or¬ 
ganisms by specific names. The names 
given to some of the less common forms 
encountered, therefore, are those of the 
types most nearly resembled. 
The studies of Levine (8 ), of Winslow, 
Ivligler, and Rothberg (15), and of 
many others on the lactose-fermenting 
group of bacteria, the work of Edson 
and Carpenter (2) and of Tanner (12) 
on the fluorescent bacteria, the investi¬ 
gations of Wenner and Rettger (14). 
and of Bengtson (1) on the proteus 
group, and of Ford and his coworkers 
(?) on the aerobic spore-bearing bac¬ 
teria, make it possible to identify 
rather definitely members of these 
groups. The common water and soil 
forms belonging to the genera Achro- 
mobacter, Serratia, and Flavobac- 
terium do not lend themselves so 
readily to identification, and it is in 
these genera particularly that no claim 
is made that the organisms so named 
are actually true to type. 
EXPERIMENTAL WORK 
In collecting the cultures from the 
dextrose-agar and wort-agar plates, 
many duplicates were inevitably ob¬ 
tained. In order to eliminate these 
duplicates, the organisms were studied 
as to their morphology, Gram staining 
reaction, growth bn agar and gelatin, 
and reactions in litmus milk and in 
dextrose, lactose, maltose, and sucrose 
broths. After the elimination of the 
duplicates, for the purpose of more 
definite identification, the following 
characters of the cultures were also 
determined: Motility; indole produc¬ 
tion; reduction of nitrates; fermenta¬ 
tion of additional carbohydrates, when¬ 
ever necessary; reaction to the methvl- 
red test and the Voges-Proskauer test, 
whenever significant; growth on po¬ 
tato; and the production of hydrogen 
sulphide. An accurate record was kept 
of the history of each organism in order 
that some data might be available on 
the source and treatment of the oysters 
from which the organism was isolated, 
its relative abundance in the decom¬ 
posing oysters, and the stage of spoilage 
at which it was isolated. 
1 Received for publication August 1, 1924; issued July, 1925. 
2 Thanks for valuable suggestions and criticisms are expressed to Charles Thom, Mycologist in Charge, 
Microbiological Laboratory. 
3 Reference is made by number (italic) to “Literature cited,” p. 975. 
Journal of Agricultural Research 
Washington, I). C. 
( 971 ) 
Yol. XXX, No. 10 
May 15, 1925 
Key No. E-34 
