Bacteria Concerned in the Spoilage of Haddock: 2. Dissociation of an Organism Resembling B. Vulgatus

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Abstract
A comparative study of aerobic, spore-forming organisms (previously isolated from living and dead haddock) found to display variation and thought related. Representative cultures were purified by the single cell method and inoculated into the usual differential media. The strains showed a general resemblance, with individual differences, and are considered a single individual species of the Subtilis-Mesentericus group. Agar plate cultures revealed 2 types of colonies in each strain. Those in the majority, "rough colonies, were identical with the form the organism takes when associated with living fish; "smooth" colonies resembled the forms originally recovered from stale fish muscle. Differences among stock strains were attributed to a different proportion of rough ("R") and smooth ("S") forms. The "R" and "S" components were studied in pure culture and displayed marked differences on nutrient agar, on potato, and in nutrient broth. Importance was attached also to the absence of spores in the "S" form. It was possible to convert each of the components into the other. The organism was identified as Bacillus mesentericus-vulgatus and is cited as an example of microbic dissociation bearing on the problem of classification in this group.