BACTERIAL GROUPS IN DECOMPOSING SALMON 



ALBERT C. HUNTER 



From the Microbiological Laboratory, Bureau of Chemistry, United States Depart- 

 ment of Agriculture 1 



Received for publication May 24, 1920 



In a previous paper (Hunter, 1920) regarding the decomposi- 

 tion of salmon the total counts of bacteria found in the muscular 

 tissue of the back and belly of the fish were given. The occur- 

 rence of these bacteria in the viscera and various organs of the 

 salmon in different stages of decomposition was also discussed. 

 The data presented were all obtained from experiments upon 

 salmon handling as conducted in the Puget Sound region. From 

 the mixed cultures and the plates made in the field 300 cultures 

 were isolated and studied with the idea of grouping or typing 

 the organisms significant in the decomposition of the salmon. 

 Special care was taken to select those colonies which predomi- 

 nated on the plates. 



It was evident that many organisms were obtained which 

 played no part in the decomposition of the fish and that there 

 were also many duplicates among the original 300 cultures. In 

 order to eliminate the organisms which did not decompose 

 salmon, and to check off the duplicates, use was made of a spe- 

 cially prepared fish broth. 2 The 300 cultures were grown in this 



1 This work was done under the supervision of Dr. Charles Thom to whom I 

 am indebted for criticism and suggestions. 



2 This medium was prepared in the following manner by Mr. B. A. Linden of 

 this laboratory: 



To 1000 grams of finely chopped saltwater trout, or weakfish, from which 

 the skin and bones had been removed, was added 1000 cc. of distilled water and 

 15 grams of peptone. The infusion was made by heating in the Arnold sterilizer 

 or on a water bath at 95° to 100°C. for one hour with occasional stirrings. The 

 juice was strained through cheese cloth with a meat press, filtered through 

 cotton and the reaction adjusted to neutral. The infusion was then heated in 

 the Arnold for thirty minutes at 100°C. and filtered, using folded filter papers. 

 About 10 cc. was placed in each tube with about 1.5 grams of raw fish. For an- 

 aerobic cultures the surface was covered with a layer of liquid petrolatum. 

 The medium was sterilized in the autoclave for fifteen minutes at 15 pounds. 



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THE JOURNAL OF BACTERIOLOGY, VOL. V, NO. 6 



