Morphological and Cultural Studies of Bacillus megatherium with special Reference to Dissociation

Abstract

The colony undergoes cyclic changes in normal development and produces secondary growth which usually reproduces the parent colony. Concentric rings may be produced in the colony on alternate exposure to lower temp. Stock cultures contain more than 1 type, and various strains may be obtained by aging normal cultures and colonies, or by growing the organism under various conditions. Several interesting strains are described, all of which were non-sporulating, and a tendency to formation of a given strain from another was observed. However, strains morphologically indistinguishable were obtained from different sources and may then possess different physiological properties. Various strains are characterized by special cellular elements: branching, club formations, budding, etc., and by special cultural and physiological properties. Germination of terminal buds, arthrospores, microcysts, and of branching and drumstick forms was observed in microcultures. The technique of making microcultures is described. The bearing of dissociation phenomena on taxonomy of bacteria is discussed. This work tends to support some form of a mutation theory as the cause of dissociation, rather than the life-cycle concept advanced by certain investigators.