A psychotropic Serratia proteamaculans 136 strain producing MccP136 was isolated from soil samples from Isla de los Estados (Tierra del Fuego, Argentina). MccP 136 production was optimized and a maximum of 800 AU ml^-1 were obtained at early-stationary phase of growth in batch fermentations carried out in a BIOFLO 101 bioreactor with a working volume of 8.1 l with pH, temperature and dissolved oxygen control. The compound was active in a broad range of pH values (1 to 13) and presented an inhibitory effect against both Gram (+) and Gram (-) microorganisms. A purification procedure was designed including activated charcoal adsorption, solid phase extraction (SPE) and RP-HPLC under semi-preparative conditions. The purity of the compound was checked by analytical RP-HPLC and monitored by photodiode array detection and purification parameters were calculated in each purification step. The molecular mass of the antimicrobial compound (479.2 g/mol) was determined in a Hybrid Quadrupole-TOF LC/MS/MS Mass Spectrometer by ion analysis. In conclusion, MccP136, a new cold-active antimicrobial is active against diverse pathogenic strains, known as etiological agents of common infections and food-borne diseases and it could be important for applications in products that involve “cold-steps” during manufacture or processing.