At a biomass of50–55 OD600the temperature was shifted from 30◦C to 42◦C. Thefed-batch cultures were ended when the biomass stopped increasing or partial cell lysis was observed.
Culture samples were analyzed immediately for biomass(OD600). Plasmid yields were determined by quantification of plas-mid obtained from Qiagen (Hilden, Germany) Spin Miniprep Kitpreparations. Acetate concentrations in culture media supernatantsamples were measured using an enzymatic acetic acid test kit (Cat.No. 10148261035, R-Biopharm, Darmstadt, Germany).