BACTERIAL GROUPS IN DECOMPOSING SALMON 551 



Identification of these 43 cultures has shown that this is actually 

 the case. Most of the bacteria isolated from the decomposed 

 salmon were originally described as water or sewage organisms, 

 although a few were originally isolated from the soil. While 

 these facts do not absolutely preclude the possibility of strict 

 anaerobes and spore-formers being present, actual examination 

 of 300 cultures from a large number of salmon in various stages 

 of decomposition has shown that the flora of decomposed salmon 

 is that of the sea-water from which they were taken. Further- 

 more, there was apparently no contamination with spore-forming 

 organisms in the boats or in the cannery subsequent to the catch- 

 ing of the fish. The bacteria isolated from fish held for four 

 days in the cannery are the same forms which were isolated from 

 the gills and mouth when the salmon were examined immediately 

 after being caught. 



The bacteria responsible for the decomposition of the fish 

 are not, in the strict sense, putrefactive and there is no rapid 

 digestion of the flesh of the fish in the cultures. Each culture 

 examined, however, did give some sort of "off" or foul odor in 

 the fish medium and many showed the character of indol pro- 

 duction when grown in this medium. It was noted that when 

 grown in a beef infusion broth, with or without a small amount of 

 carbohydrate added, no odors suggestive of decomposition were 

 obtained. This makes it apparent that the flesh of fish is more 

 susceptible to decomposition by ordinary water bacteria than 

 is the flesh of the higher animals. 



Although the salmon, when not feeding, has no bacteria in 

 its intestines which may play a part in its subsequent decom- 

 position, the accumulation of ordinary water bacteria in the 

 gills and mouth and on the skin provides a flora which brings 

 about a slow decomposition of the body of the fish after death. 



SUMMARY 



In a study of the bacteria which decompose raw salmon, 43 

 cultures were isolated as significant. On identification 21 cul- 

 tures were found to be members of the colon-cloacae group. 

 One culture resembled Bad. alcaligenes and 3 cultures resembled 



