TLC and PC are used for bioautography, but the detection method can be sucessfully improved by the application of advance chromatographic tool namely high performance thin layer chromatography ( HPTLC ), over pressuried layer chromatography ( OPLC ) and planar electro chromatography ( PLC ) .....The zones of the zones of inhibition corresponding to the spots in chromatographic plate are indicative of the substance in question. For more details consult https://www.ncbi.nlm.nih.gov