Serratia marcescens N10612, isolated from soil culture, was found to produce the bio-active prodigiosin isoform pigment (PIP) through nutrition tests. The complex medium consisting of sucrose, peptone and yeast extract was found to be the best composition for PIP production. The optimization of PIP production was carried out by using statistical experiment designs. The optimal concentrations of medium were yeast extract 5.6 g/L, peptone 6.9 g/L, sucrose 31.6 g/L and NaCl 1.0 g/L. Under the optimal conditions, the predicted production of PIP was 1307 mg/L, while the experimental value was 1303 mg/L. Further identification by high resolution mass spectrometry and MNR revealed that the PIP products were prodigiosin and its isoforms. The PIP produced by this strain belongs to shorter carbon chains isoforms (15, 17, 18, 20-C) mentioned in the report. These PIPs are expected to have bioactive functions in medical and clinical applications.