We also constructed a cmcax complement strain, F2-2(pSA-CMCase/
k), in which the complementation plasmid pSA-CMCase/k (an
approximately 1.9-kb fragment of G. xylinusDNAwith cmcax and
aKmr gene included in the shuttle vector pSA19) was inserted into
F2-2. A 5-mm-thick pellicle (Fig. 1B, arrow) was formed after 1
week of static culture of the wild-type strain. Pellicles were not
formed in the 1-week static F2-2 culture, but small amounts of
particulate material (Fig. 1C, arrowheads) were observed at the
bottom of the flask or attached to the inner surface of the flask at
the border between the medium and the air. As expected, a thick
pellicle (Fig. 1D, arrow) was also formed in the static F2-2(pSACMCax/
k) culture.