The preservation of fresh fish by fast-freezing is an industry which is undergoing logical development because of certain advantages which it affords. It offers speed and economy, and the characteristics of content of flavor and vitamin are retained. It was decided to investigate the effect of fast-freezing upon the bacterial flora of mackerel, which is one of the important fish for food of the California coast and which is available regularly. Numerous examinations of the flora of fish from marine waters have been made previously and they have yielded comparable results ; nevertheless, in a problem of this nature it was necessary to acquire data regarding the nature and amount of the bacterial flora of this particular variety of fish in this locality in order to determine the effect of freezing upon its microorganic content.
WORK OF PREVIOUS INTESTIGATORSHunter (1920b) determined that the flora of decomposing salmon was the same as that of sea water and described it as consisting of soil, water, and sewage microorganisms. Reed and Spence (1929), in their study of intestinal and slime flora of haddock, reported the presence of Protezts, Pseudomonas, Achromobacter, Flavobacterium, and Bacillus in both intestinal contents and slime. Micrococcus was reported chiefly from slime, while colon forms-Escherichiu, Balmonellu, Aerobacter, and Eberthellawere demonstrated only in the intestine.Sanborn (1930) studied the bacterial decomposition of fresh, smoked, and iced fish and reported that marine bacteria were constantly in or. on fresh fish and on smoked and frozen fish. They were active even a t low temperatures; most of them were proteolytic and a few were putrefactive. Smoked fish were attacked by Torula, Penicillium, and Achromobacter, while the iced fillets were invaded by Proteus, Eberthella, Micrococcus, and Cheatostylum, all strains of which withstood -18 to -23' C. (-0.4 to -9.4"F.) for months. Bedford (1933a), in his survey relating to preservation of fish, reported the following genera of bacteria to be present: Achromobacter, Flavobacterium, Xerratia, Micrococcus, and Rhodococczts. The quantities on the surface of the fish were smaller than those found in the sea in the vicinty, while the numbers in the alimentary canal of a fish depended upon its feeding habits ; bottom feeders contained larger numbers than did others. Wood (1939) reported the isolation of Micrococcus, Plavobacterium, Achromobacter, Pseudomonas, and Bacillus from fish 'This work was made possible by an Ellen Browning Scripps Fellowship. We are indebted to Dr. C. E. ZoBell f o r helpful advice. Present address : Lederle Laboratories, Pearl River, N. Y.