Studies on the colonial morphology of Bacillus cereus var. mycoides



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Rhizoid cultures of B. cereus var. mycoides can dissociate to form non-rhizoid cultures which are in fact B. cereus. This dissociation is unidirectional from rhizoid to non-rhizoid colonies. This investigation demonstrates that rhizoid cultures may be transformed into non-rhizoid colonies when grown in the presence of silica, crystal violet, cupric sulfate, sodium lauryl sulfate, or large amounts of amino acids. When such non-rhizoid colonies are transfered to nutrient agar they revert to their former rhizoid form. These substances do not effect the colonial morphology of B. cereus. This observation may indicate that there is a surface component present in rhizoid forming organisms which is either altered or not present in non-rhizoid bacteria. Differences are demonstrated in the amino acid composition of non-dlalysable material from autoclaved supernatants of B. cereus and B. cereus var. mycoides. The consistency and nature of the polymerizing agent in solid media effect the conformation of filaments. This may occur if filaments grow in directions of least resistance.