FIG. 9.

Complementation of an E. coli hfq mutant with the M. catarrhalis Hfq protein. (A) Growth curves of wild-type, mutant, and recombinant E. coli strains. The wild-type strain MC4100 (⋄), the hfq mutant GS081 (▪), the hfq mutant with the M. catarrhalis hfq gene provided in trans [GS081(pAA105)] (▴), and the hfq mutant containing the negative control plasmid [GS081(pAA105B)] (○) were suspended in LB broth to an OD₆₀₀ of 1.0 and then diluted 1:20. These cultures were allowed to grow with aeration at 37°C, and the growth was monitored by measuring the absorbance at 600 nm every hour. (B and C) Cells of the wild-type, mutant, and recombinant E. coli strains were suspended to the same OD₆₀₀ and then serially diluted and spotted onto BHI agar (B) and onto BHI agar containing 40 μM methyl viologen (C). The plates were dried and incubated overnight at 37°C.