Fig. 3
Cultivation of Paenibacillus polymyxa with increased pH — buffer capacity in microtiter plate. Moppa medium (specified in Table 2) with 12 × nicotinic acid or Moppa medium with 12 × nicotinic acid and with increased buffer concentration or with increased buffer concentration and initial pH. nic.: nicotinic, pH0: initial pH. Initial concentrations were: 62.1–63.4 g/L maltose, 1.9–2.1 g/L glucose, 3.7–3.8 g/L citrate. a Oxygen transfer rate (OTR), b Final optical density (OD) and pH, c Final maltose, glucose and citrate concentration, d: Final acetoin and 2,3-butanediol concentration. a For clarity, only every 12th measuring point over time is marked as a symbol. Mean values for OTR of at least four replicates with standard deviations as shadows are shown. b-d For offline analysis, samples (wells) of the replicates of the OTR measurement were pooled at the end of the experiments. OD measurement of pooled samples was performed in triplicate and mean values with standard deviations depicted as error bars are shown. pH and concentrations of sugars and metabolites were determined in a single measurement of pooled samples. c d.l. means that concentrations of components were lower than the detection limit. Final lactate concentrations were lower than the detection limit. Parameters in c-d were determined after 86.3 h. Osmolalities are shown in Additional file 1: Figure S6. Cultivation conditions: temperature 33 °C, 48-round well plate, filling volume 0.8 mL, shaking frequency 1000 rpm, shaking diameter 3 mm