And in order to evaluate the effect of agitation speed on γ -PGA
Production. As shown in Fig. 2, although the maximum cell growth was observed at 400 rpm, γ –PGA concentration (17.2 g L−1) and viscosity (2.16 cP) were low at this agitation speed. This result might be due to high shear stress from the relatively rapid agitation rate. Similar γ -PGA concentrations were observed at 200 rpm (40.4 gL−1) and300 rpm (41.1 gL−1).