Reproduction of Bacteria from the Large Bodies of Streptobacillus moniliformis. †

Abstract

In most strains of Streptobacillus moniliformis the bacteria develop by gradual swelling into large round forms. These forms transplanted under appropriate conditions germinate by the growth of small soft granules and diphtheroid-like forms and produce a pleuropneumonia-like, L1, colony. 1 Similar enlargement of bacteria and development to pleuropneumonia-like colonies was observed in the cultures of B. funduliformis, B. coli, and B. influenza. 1 In a culture of B. coli 2 and in the cultures of several strains of B. funduliformis 3 the large bodies went through another type of development and produced bacteria of the usual shape and size. A similar process was observed recently in a strain of Streptobacillus moniliformis.

The strain which showed this phenomenon was received from Doctor Heilman. It was preserved without being transplanted in CO₂ refrigeration. The strain grew in small colonies which after 24 hours consisted of intertwined filaments with relatively few large bodies. After 48 hours the colonies consisted mostly of very large flat bodies (up to 20 microns in diameter) filled with vacuoles of various size. The bacterial filaments in these colonies were to a large extent autolyzed and stained only faintly. L1 colonies did not develop beneath the bacterial colonies but they developed in moderate numbers among the bacterial colonies in transplants. The bacterial growth in young cultures often was first noticeable in the form of very tight round colonies in contrast to the usual loose colonies of the streptobacillus. This observation suggested that the bacterial growth started from the large bodies.

To examine this supposition, agar blocks inoculated with 24- and 48-hour-old cultures were incubated on coverslips. The blocks after varying lengths of incubation were fixed