In many cases it might be useful to apply the fed-batch principle already in the earliest process optimization phase, not primarily for obtaining higher cell densities, but for applying similar physiological conditions as in the later process. As such tools are not commonly available we developed a new feeding system which works wireless and therefore can be easily applied on any shaker. If powered by a lead accumulator, the feeding unit can be C-P4H activity in three different experiments, each with a quasi-continuous feeding culture (black bars) and a reference culture (manual feeding twice a day, white bars) Figure 5 C-P4H activity in three different experiments, each with a quasi-continuous feeding culture (black bars) and a reference culture (manual feeding twice a day, white bars). Additionally, in experiment no. 4 double concentrated methanol was fed (grey bar). mRNA levels of a) procollagen II chain, b) AOX1, c) translation factor EF3, and d) C-P4H α(I) subunit during shake flask culti-vation of P. pastoris Figure 6 mRNA levels of a) procollagen II chain, b) AOX1, c) translation factor EF3, and d) C-P4H α(I) subunit during shake flask cultivation of P. pastoris. Predetermined quasi-continuous feed of methanol was investigated. The cells were first grown in BMG medium and changed to BMM medium at 0 h. The first sample represents the time when the methanol feeding was started (13 h) . Predetermined constant feed (red filled circles); reference culture with pulse Feeding (open blue circles). The data are from experiment 4 in Table 1 .