## 3 Results
### [ATP]/[ADP] Ratio, ATPase Activity, and cAMP Concentration Determinations  
The energetic level of the studied strains was determined using an analysis of the [ATP]/[ADP] ratio, ATPase activity, and cAMP concentration. All determinations were performed in the analyzed strains growing in aerobic bioreactor cultures when DO\({}_{600 nm}\) = 1.0. Results are shown in Table 2. The parental strain JM101 showed the highest [ATP]/[ADP] ratio = 7.32. This result is consistent with previous reports for parental strains of _E. coli_ ranging between 6-10 [9] and for the strain JM101, as determined previously [6]. The ratio [ATP]/[ADP] decreased by 65% in the PB12 strain and 84% in the mutant PB12 AGD\({}^{+}\) and compared to JM101, respectively, corresponding to a decrement of 52% in the _apt_ mutant than the observed in PB12 (Table 2). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Strain**} & \(\mathbf{\mu}\) & \multirow{2}{*}{\(\mathbf{\sigma_{\text{Gic}}}\)} & \multirow{2}{*}{\(\mathbf{Y_{\text{Xyclic}}}\)} & \multirow{2}{*}{\(\mathbf{\sigma_{\text{Age}}}\)} & \multirow{2}{*}{\(\mathbf{\sigma_{\text{Age}}}\)} & \multirow{2}{*}{\(\mathbf{q_{\text{G2}}}\)} & \multirow{2}{*}{\(\mathbf{[ATP]/[ADP]}\)} & \multirow{2}{*}{\(\mathbf{[ATP]/[ADP]}\)} & \multirow{2}{*}{\(\mathbf{[ATP]/[ADP]}\)} \\  & (\(\mathbf{\text{Gic}}\)/\(\mathbf{\text{Gpcv}}\) h) & (\(\mathbf{\text{g/g}}\)) & & & & & & & & \\ \hline JM101 & 0.71 \(\pm\) 0.04 & 1.74 \(\pm\) 0.04 & 0.41 & 0.10 \(\pm\) 0.01 & 8.41 \(\pm\) 0.36 & 1.58 \(\pm\) 0.06 & 7.32 \(\pm\) 0.14 & 1.46 \(\pm\) 0.05 & 24 \(\pm\) 1.25 \\ PB12 & 0.43 \(\pm\) 0.02 & 0.81 \(\pm\) 0.08 & 0.53 & 0.02 \(\pm\) 0.00 & 5.60 \(\pm\) 0.02 & 0.5 \(\pm\) 0.01 & 2.53 \(\pm\) 0.03 & 1.47 \(\pm\) 0.01 & 29.92 \(\pm\) 1.98 \\ PB12 AGD\({}^{+}\) & 0.24 \(\pm\) 0.04 & 1.42 \(\pm\) 0.07 & 0.17 & 0.06 \(\pm\) 0.00 & 7.34 \(\pm\) 0.07 & 1.19 \(\pm\) 0.03 & 1.20 \(\pm\) 0.01 & 1.97 \(\pm\) 0.01 & 21.44 \(\pm\) 2.02 \\ \hline \end{tabular} All data are shown in the average obtained from four independent experiments and SD values. The difference in measured metabolite concentrations among independent experiments was in the range of 1–10%. \(\mu\) = specific growth rate \(\dot{\sigma_{\text{Gic}}}\) = specific glucose consumption; \(\dot{\text{Y}_{\text{Xyclic}}}\) = rate yield biomass/substrate; \(\dot{\text{\sigma}_{\text{Age}}}\) = specific production rate of acetic acid; \(\dot{\text{\sigma}_{\text{Age}}}\) = base addition rate; \(\dot{\text{\sigma}_{\text{G2}}}\) = oxygen consumption specific rate; \(\dot{\text{\sigma}_{\text{SOCN}}}\) = grams of dry cell weight. Data analysis and calculations were performed as described previously [16]. Linearizations were made to obtain apparent biomass on the substrate (\(\dot{\text{Y}_{\text{X/S}}}\)) yield. Correlation values for linearizations in all experiments were \(\gtrsim\)0.95, allowing comparisons between them. The yield value was used to calculate the specific productivity and consumption rates on the exponential phase.  
\end{table} 
Table 2: Physiological parameters determined from bioreactor cultures of JM101, PB12, and PB12 AGD\({}^{+}\) strains. Figure 1: Growth curves of the parental _E. coli_ JM101 strain (\(\bullet\)) and the PB12 (\(\blacksquare\)) and PB12 AGD\({}^{+}\) (\(\blacktriangle\)) derivatives conducted in bioreactors. These aerobic cultures were performed in M9 supplemented with glucose (2 g/L). All experiments were performed in duplicate, and the reported values represent the mean values of at least four independent experiments. The difference in measured metabolite concentrations among independent experiments was in the range of 1–5%. As stated, enzymatic assays were performed from cellular extracts; thus, the ATPase activity encoded with the plasmid-cloned _atpAGD_ operon in the PB12 strain is considered as the total ATPase activity as it is not coupled to any other cellular enzymatic activity.