FIG 1.

The zipA1 mutant in W3110 displays a medium-dependent cell division defect at the permissive temperature. Wild-type E. coli W3110 exhibited normal cell morphology when grown at 30°C in LB (A), MOPS (B), M9 (C), M9 plus 1% Casamino Acids (Cas AA) (D), M9 plus 0.5 mM glycine (E), or M9 plus 0.5 mM l-threonine (F). The thermosensitive zipA1 mutant (WM2991) was slightly elongated in LB (G), filamented in MOPS (H), and filamented with some misshapen cells in M9 (I), and these defects were partially suppressed when M9 was supplemented with 1% Casamino Acids (J), glycine (K), or l-threonine (L). (M) The bar graph represents the growth of W3110 (wild-type zipA) and WM2991 (zipA1 allele) in M9 and the effects of different l-amino acids on the growth of WM2991 after 22 h at 30°C. Scale bar, 4 μm.