Effect of gramicidin A and valinomycin on prodigiosin production by non-proliferating Serratia marcescens.

different concentrations of gramicidin A. O 10 /Mg/ml, A 5 ^g/ml, å¡ 20 ^g/ml, ® 40 ^g/ml, ffl 40 ^g of gramicidin A/ml with only L-proline, A 40 fig of gramicidin A/ml alone and v is 40 jug of gramicidin A/ml and 300 fig of polymyxin B/ml without L-proline. Prodigiosin is a secondary metabolite produced by some strains of Serratia marcescens and other taxonomically unrelated bacteria. Some authors have reported that prodigiosin exhibits antimicrobial activity against Gram-positive bacteria, fungi and protozoa1'^. Non-proliferating cultures (NPC) of S. marcescens are unable to produce prodigiosin unless they are induced by certain amino acids such as L-proline3). When NPC were induced with