SCREENING OF GAMMA-CYCLODEXTRIN-PRODUCING RECOMBINANT ESCHERICHIA-COLI USING CONGO RED-DYE ON SOLID COMPLEX MEDIA

Recombinant genetic cloning of cyclodextrin glucanotransferase (EC 3.2 .1.19) bacterial genes into E. coli has spurred the need for a rapid s olid media screening analysis for recombinants. A number of qualitativ e and quantitative colorimetric assays have been previously developed for cyclodextrins (CDs) based on the changes in colored dye spectral r esponse upon chelation in CDs. However, none are applicable at the scr eening conditions needed for recombinant E. coli (neutral pH, colored complex solid media). We report a qualitative colorimetric detection m ethod for gamma cyclodextrins produced from recombinant E. coli at neu tral pH in complex media using congo red and xylene cyanole dyes.