Fermentative production of piperazinium dilactate

In order to test whether piperazinium dilactate can be produced by fermentation in its exact stoichiometric composition without losses of yield, the kinetics of cell growth and lactate production were investigated in the batch cultivation of Lactobacillus paracasei, using piperazine as a neutralizer in pH control. It was found that piperazine dilactate is formed in its stoichiometric composition at about pH 5.0, and lactic acid fermentation occurred with yields of about 90% under these conditions. Piperazine at concentrations less than or equal to 50 g/l did not affect growth and product formation. The presence or absence of piperazine did not produce any significant differences in either the maximum specific growth rate or the maximum specific lactate formation rate when piperazine was present or absent (0.65 h^-1 compared to 0.68 h^-1 and 3.86 g/g × h compared to 3.63 g/g × h, respectively). The Luedeking-Piuret relationship between the two quantities was also not changed significantly when piperazine was added. To estimate the optimum parameters for cell growth and lactate formation in the presence of piperazine, a factorial experiment was designed and carried out under consideration of the parameter ranges 5.0 ≤ pH ≤ 7.0 and 30 °C ≤ T ≤ 36 °C. In this way, three-dimensional models of the specific growth rate, the specific lactate formation rate and the lactate yield were obtained.