3.2 | pH control
To assess the efficacy of pH control, six bioreactor modules were operated independently in batch culture mode. All bioreactor modules were inoculated with an active E. coli BL21 culture. One group had no pH control (Figure 3A) and the other group was set to maintain pH 7 (Figure 3B). The pH of the cultures was monitored for 24 h and samples of the cultures were collected for assessment of optical density at regular intervals over the course of the experiment. The cultures ofE. coli maintained at pH 7 showed enhanced growth during the exponential growth phase compared to the cultures without pH control. The volume of acid and base added to the growth medium to maintain pH 7 are shown in Figure 3C. These results demonstrated the ability of the bioreactor modules to maintain a steady pH of the culture at a predetermined value.