Abstract Summary (Max 250 words)
Microorganisms are used to produce a wide range of compounds, including biopolymers. For this purpose, both wild-type and genetically modified strains can be utilized. One example is genetically modified E. coli, a strain used for the production of P3HB, a polymer belonging to the PHA group. The source of organic carbon in such bioprocesses is often glucose; however, it may also consist of wastes derived from industry or agriculture. The aim of this study was to investigate the effects of mixing on the optimization of the growth of genetically modified E. coli used for the production of poly(3-hydroxybutyrate) under aerobic conditions, with glucose as the primary carbon source. An additional objective was to select an appropriate (radio)tracer for determining RTD. Such investigations are particularly important due to the possibility of bacterial growth at high cell density, where significant oxygen limitation may occur. The measurements were carried out in two bioreactors, BioFlo 310 and 415, with aeration and working volumes of 5 and 10 dm³, to study the scale effect. The influence of impeller speed and air flow rate on the oxygen transfer was analyzed. The measured kLa values were compared with correlations reported in the literature, and modifications to the empirical expressions were proposed to achieve better agreement with experimental data. The results obtained may be used particularly for: 1) validation of CFD models; 2) determination of the enhancement coefficients under aerobic microbial cultivation; 3) intensification of microbial growth and their metabolites, including the potential for scale-up.
