Table 1. P_r promoter activity at different induction levels of Rco_LS20.

[IPTG] (µM)	βGA (MU)
0	<0.1
10	0.2
20	0.7
50	1.2
100	0.4
200	0.3
500	0.2
1.000	<0.1

Overnight culture of GR92 cells grown in the absence of IPTG was diluted 100-fold in fresh prewarmed LB medium containing the indicated amount of IPTG at 37°C. βGA was determined for samples withdrawn at late exponential growth (0D600 = ∼0.8). Background levels obtained with negative control strain PKS7 were <0.1 MU. Values are the mean of three independent experiments and for each point fluctuations were less than 10%. βGA, β galactosidase activity.