Indicator plates for rapid detection of ribonuclease T1 secreting Escherichia coli clones.

Fig. 1: Section of an RNase indicatorplate. After overnight incubation at 37°C an RNase secreting colony (left) showed pink halos against blue medium. An E. coli colony not secreting RNase is shown as a control (right). The lest agar contained toluidine blue O (SO mg/1, Merck, Darmstadt: FRG) and yeast RNA (2 g /1 , Boehringer, Mannheim; FRG) in solid LB medium (1.5 % Agar). RNA stock solution (pH adjusted to 7.0 using 1 N NaOH) was added at 50°C to autoclaved medium. 10 1 10 100 RNase c o n e