Fig. 4

Promoter characteristics of P_lacA and growth behavior. a, c MRS medium with glucose and 5 μg ml⁻¹ CM; b, d MRS medium with galactose and 5 μg ml⁻¹ CM; e, f MRS medium with 5 μg ml⁻¹ CM. Mean values of four replicates are given and standard deviations are indicated. Filled circle induced, 2 % lactose. Filled diamond induced, 0.5 % lactose. Circle non-induced. a, b specific expression levels of mCherry under control of P_lacA after induction with 0.5 and 2 % lactose (or no induction) after 2 h in BioLector^® micro-fermentation. Change of mCherry expression (RFUs, relative fluorescent units) over time (hours) of P_lacA mediated expression in comparison to the negative control is shown (solid line). c, d corresponding calculated OD₆₀₀ values. e, f RFU and growth in selective MRS with lactose as main carbon source; x: induced, 2 % lactose; +: induced, 0.5 % lactose; filled circle induced, 2 % lactose and 2 % galactose as additional carbon source