Prodigiosin is a red pigment produced by many strains of Serratia marcescens and other microorganisms such as Pseudomonas magneslorubra and Vibrio psychoerythrous. The pro — digiosin group of natural products belongs to the Psychroerythrus family of tripyrrole red pigments that contain a common 4-methoxy, 2-2 bipyrrole ring system. The biosynthesis of the pigment is by a bifurcated process in which mono — and bipyrrole precursors are synthe­sized separately and then assembled to form prodigiosin (Boger and Patel 1988). This pigment is capable of inducing apoptosis in several cancer cell lines, except nonmalignant cells. It can be used, therefore, as a potential antineoplastic candidate. Serratia marcesens has been reported to use crude glycerol as a carbon source to produce up to 583mg/L of prodigiosin (Tao et al. 2005).

Astaxanthin

Astaxanthin is a red or orange pigment usually included in marine feed to improve fish color and visual appeal. In their natural habitat, the food chain provides chemicals and nutrients that give some species of marine fish their characteristic pink color. To retain this pink color under artificial environment, astaxanthin is often incorporated into fish feed. Astaxanthin is naturally produced by the yeast Phaffia rhodozyma from P-carotene via a two-step reaction catalyzed by P-carotene ketolase and P-carotene 3,3’-hydroxylase. This organism has been reported to ferment crude or industrial glycerol to produce 34 mg/L of astaxanthin (Kusdiyantini et al. 1998).