Physical and chemical stress on Serratia marcescens and studies on prodigiosin pigment production

Abstract

Bio-pigments play a very important role in many industries such as food, feed, cosmetics and pharmaceutical products. The red pigment prodigiosin produced by Serratia marcescens possesses a lot of medical benefits. The employment of ultraviolet (UV) radiation and ethyl methanesulfonate (EMS) to induce variants with the enhanced pigmentation of S. marcescens is the main scope of this study. Also, the antimicrobial activity and the cytotoxicity properties of prodigiosin were investigated. Subsequent to physical and chemical stress induced on S. marcescens, many variants are selected. They showed different patterns in growth at 38 °C, salinity tolerance, emulsification and hemolytic activities compared to the parent S. marcescens. The EMS-variant (S26) produced prodigiosin eight-fold higher than that of the parent strain. Three new media are described for S. marcescens’s growth and pigmentation. They are based on the market-refused squash seeds; sunflower seeds and watermelon seeds. The present study modifies and designs a new procedure for prodigiosin extraction using small volumes of bacterial cultures. Prodigiosin was purified using column chromatography; it was found that prodigiosin is susceptible to non-polar solvents. Crude prodigiosin extracted from variant (S26) is stable at alkaline pH and its thermal stability is up to 80 °C. The experiment of testing the dyeing properties of prodigiosin is outlined and its results are deeply encouraging for the use of this interesting pigment for ultimate medical applications.