Standard culture conditions (circles) are suitable with respect to both, cell growth and protein yield for GFP (black line, closed circles). Despite the fast growth rate of GFP-perlucin cells under standard conditions (black line, open circles), the final protein yield is low (Figure 2B). When these cells are cultivated using the optimized temperature profile, cell densities reach an O.D. (optical density) of ∼2.6 after 22 hours (light grey triangles) and protein yields increase (Figure 2C). Perlucin expressing cells divide slower under both, standard (grey circles) and optimized (dark grey triangles) growth conditions to a maximum O.D. of 1.6 after 24 hours, suggesting a possible toxic effect of perlucin on cell proliferation. Regardless of culture conditions, recombinant perlucin can hardly be purified natively (Supporting Information file Figure S1).