Hello everybody,

 I construct gene libraries, transform them into E. coli KA12 and select on M9c minimal agar medium. Some of the clones exhibit intense slime production (wet, shiny and mucoid appearance), which causes fusion of the nearby colonies and therefore severely interfering with my experiment. Is there a way to reduce the slime production by varying growth conditions?

The medium I use:

·      M9 salts (6 mg/mL Na2HPO4, 3 mg/mL KH2PO4, 1 mg/mL NH4Cl, and 0.5 mg/mL NaCl, pH 7)

·      0.2% (w/v) D-(+)-glucose,

·      1 mM MgSO4,

·      0.1 mM CaCl2,

·      5 μg/mL thiamine-HCl,

·      5 μg/mL 4-hydroxybenzoic acid,

·      5 μg/mL 4-aminobenzoic acid,

·      1.6 μg/mL 2,3-dihydroxybenzoic acid,

·      20μg/mL L-tryptophan

Antibiotics:

Kanamycin and chloramphenicol

Inducers of my proteins of interest:

Salicylate, tetracycline and propionate.