Dear Kay-Dietrich,

I think some kind of cell concentration will be necessary to arrive at readily detectable luciferase concentrations. Doing the lysis directly in the culture medium may also interfere with the detection (lower signal / higher background), further compromising sensitivity, but you may simply give it a try (freeze-thaw and/or add a detergent such as 1% Triton X-100 or NP-40)

Is there a reason not to pellet the cells before doing the assay? If your cells are sensible towards centrifugation, try a gentle run (~ 100 g) or even consider sedimentation only by gravity (just let the suspension sit for ~ 1 h, but be careful not to disturb the loose pellet afterwards).

Finally, maybe take a look at the novel live cell luciferase substrates which do not require lysis (e.g. "Nano-Glow"), which may be more appropriate for your particular application.

Best regards,

Patrick

Dear Patrick,

Thank you very much for your comments. The cells are not sensitive to centrifugation and I did a lot of "classical" luciferase assays before. We want to go to the next HTS level and the robots are not able to go to the centrifuge or the freezer. Steady glow or steady-lite should do the trick. I will try.

Best

Kay