Growth characteristics of strains MGB874 and 874ΔrocG producing alkaline cellulase Egl-237. The strains MGB874 (open symbols and dotted lines) and 874∆rocG (closed symbols and solid lines) were transformed with pHYS237, and cultured in 2xL medium containing 12.5% (w/v) maltose monohydrate by the pH-Stat fermentation using 2-L jar fermentor. Fermentation without pH control was done as a reference (A). The pH was adjusted to 7.2 by the automatic addition of 1M NaOH (B) or 10% (w/v) aqueous NH3 (C). Cell yields (circles) and extracellular cellulase activities (triangles) were shown on the left side of the figure. Residual ammonia concentrations (diamonds) and external pHs (crosses) in the growth media were shown on the right side of the figure. Additionally, total amounts of ammonia fed (squares) were also displayed under the NH3-pH auxostat. Arrows indicate the point at which transcriptional analysis was conducted.