IDENTIFICATION OF COCCOID ESCHERICHIA-COLI BJ4 CELLS IN THE LARGE-INTESTINE OF STREPTOMYCIN-TREATED MICE

Escherichia coli BJ4, a rat isolate, was used to examine the growth an d differentiation of the microorganism in its natural habitat, the int estine. Growth of E. coli BJ4 in the large intestine of streptomycin-t reated mice was compared with its growth in laboratory media. By a num ber of methods, it was shown that E. coli BJ4 differentiates, during g rowth in the intestine, into two distinct populations, one that has th e characteristics of the laboratory-grown strain and one that appears as a coccoid cell. Furthermore, it was shown that there is a natural s election for the coccoid-type cell in the intestine, while in laborato ry media growth of rod-shaped E. coli BJ4 is enhanced.