Optimization of Prodigiosin Production in Serratia marcescens: Effects of Growth Parameters on Antimicrobial and Cytotoxic Activities

In this study, we isolated a red-colonial strain from marine soil collected in Colachel, Kanyakumari, Tamil Nadu, and identified it as Serratia marcescens via 16S rRNA sequencing. Optimization of various growth parameters was performed to increase pigment prodigiosin production. Mannitol was found to be an ideal carbon source with an optical density (OD) value of 1.99. A pH level (OD 1.92) and temperature of 27°C (OD 1.95) also promoted the favorable synthesis of pigment. Moreover, low salt concentration (0.5% NaCl) and a prolonged incubation period (120 h) significantly increased prodigiosin yield. It was found that higher prodigiosin production was achieved under shaking conditions (OD 2.25) than under static conditions (OD 1.12), and the pigment was maintained in methanol. The prodigiosin exhibited a strong antimicrobial effect against Staphylococcus aureus, with a zone of inhibition (ZOI) of 38 mm.