Finally, by combining a growth controlled (reduced temperature (35 °C), low dO2) initial batch phase with an adaptive feeding strategy in the fed-batch phase (37 °C, glucose-/dO2-limitation) we were reproducibly able to produce up to 250 mg/L of plasmid DNA in cultures that reached a final OD600 of 80.
In order to study changes on the (bio chemical composition of the cells, the fermentation was carried out in two parts: a batch phase, with an excess of glucose (C-source) and ammonium (N-source), and subsequently a C-limited fed-batch phase during which no additional N-source was fed and trehalose and glycogen were accumulated inside the cells.
The SSF process of LTWS to lactic acid consisted of three phases: (1) the prehydrolysis phase of preloaded LTWS, (2) the fed-batch phase with automatic feeding of LTWS from a screw feeder, and (3) the batch phase with pH control by a calcium hydroxide suspension and no LTWS feeding.
One might also assume that, in endangered environments, phage propagation may be avoided by applying controlled low growth rates from the beginning of the cultivation process, and thus by avoiding batch phases with fast bacterial growth rates.
Until all of the glycerol was consumed, then the process was converted to a glycerol fed-batch phase, with feeding of 50% (v/v) glycerol containing 1.2% (v/v) trace solution at the average rate of 12.4 g/L/h.
As with glucose fed-batch cultures, one can predict that a lower C/N in the batch phase, possibly combined with a high C/N feed, would be necessary to achieve more complete utilisation of the substrate and to create a process which would be sustainable as a repeated fed-batch process.
In essence, this fermentation protocol consists of only two phases: a glycerol batch phase and a methanol/glycerol fed-batch phase.
A glycerol batch phase is followed by a transition phase and by a methanol induction phase [ 14].
A glycerol-fed batch phase was next carried out with a batch using 50% (w/v) glycerol for approximately 12 h, followed by a period of 0.5 h without any feeding, to allow the glycerol to be fully consumed.
