FIG. 1.

Electron micrographs of thin sections of L. monocyotgenes. (a) Resistant parent strain H7962P grown in TSB. Scale bar = 100 nm. (b) Adapted resistant strain H7962A grown in the presence of 8 μg of BC per ml. Scale bar = 200 nm. (c) Sensitive parent strain LJH381P grown in TSB. Scale bar = 100 nm. (d) Adapted sensitive strain LJH381A grown in the presence of 5 μg of BC per ml. Scale bar = 100 nm. Compared with the parent strains, adapted strains were elongated and slimmer. Waviness and shedding of unknown materials were apparent in adapted strains.