The Reddening of Salted Hides and Fish

Fairly systematic investigations into this phenom- enoni seem to go back to 1922 when Harrison and Ken- nedy, working in Canada, succeeded in cultivating red- pigmented organisms from specimens of salted fish displaying the phenomenon known as "Red Eye."This highly characteristic red growth was the source of con- siderable economic loss in the Canadian fishing indus- try and was traced by the authors to the presence of red-pigmented organisms in the salt or brine used for curing.They came to the conclusion that tropical salts were the most serious sources of contamination, although subsequent investigations have shown that most unsterilized marine salts are contaminated by these bacteria.An early investigation of red heat on hides was made by Bergman (1929) who, unfortunately, came to some erronieous conclusions through the use of unsuitable media, finally attributing the coloration to strains of Micrococcus roseus.Bergman, however, published some photomicrographs showing that hides displaying red heat had evidence of bacterial digestion on the flesh side.. Jordan-Lloyd (1929) and co-workers, using a modi- fication of a medium proposed by Clayton and Gibbs (1927) isolated strains of red, yellow, and colorless organisms from numerous samples of marine salt, and also demonstrated that mined salt from Cheshire was free from these bacteria.They formed the opinion that although these bacteria themselves seemed in- capable of digesting hide substance, hides showing evidence of red heat seemed more liable to putrefy.Harrison and Kennedy (1922) were of the opinion that their numerous isolates represented one species only to which they gave the name Pseudomonas sali- naria.This was later transferred by Bergey (1923) to the genus Serratia, and later still (1925) back to the Pseudomonas.Lochhead (1934a, b) investigated the bacterial flora of red heat occurring on three hides of different geographical origin, and isolated three strains of red organisms and a number of colorless halophiles.He identified one of them with Harrison and Kennedy's P. salinaria, another with a species of sarcina previously isolated in tidal mud near Copenhagen by Poulsen (1879) anid to which the name Sarcina liltoralis had been given, and a third strain, considered a niew species, to which he gave the name Serratia cutirubra.This species also was transferred to the Pseutdomonas (Breed, Murray and Hitchens, 1948).Later, Stuart (1935) published a remarkable paper in which he claimed to have identified the causal agent of red heat with Myxococcus rubens.Space does not allow a detailed analysis of this claim, but it seems to rest on somewhat doubtful evidence.The writer has been unable to reproduce any of Stuart's experimental results, and it is only possible to conclude that he was dealing with an unusual case.Harrison and Kennedy (1922) gave a good description of P. salinaria.Somewhat abridged, it is as follows:Occurs as spheres and rods, extremely pleomorphic, motile, gram negative.Does not grow on ordinary culture media.Grows well on salted fish.Codfish agar; growth slow, smooth, raised, coarsely granular, entire, pale pink to scarlet.No acid from carbohydrate.Aerobic, facultative.