Screening And Identification Of A Prodigiosins-producing Strain And Optimization Of Its Fermentation Conditions

Prodigiosins (PG), a family of natural red pigments extracted from some species of Streptomyces, Serratia, Pseudomonas and other genus, is a kind of typical alkaloid compounds produced as secondary metabolites, usually have three pyrrole ring skeleton. It was reported that some members of this family showed a variety of drug activities, such as antibacterial, antimycotic, antimalarial, antitumor, cytotoxic and immunomodulating, displaying important medicinal properties. The main work contents and results of this thesis are as follow.1. A red-pigmented bacterium NS-17 was isolated from the soil of NanChang area. Morphological, physiological and biochemical characteristics of the strain NS-17 were studied, all the results surported that the strain was a member of Serratia marcescens,99% similarity of 16S rDNA between NS-17 and some other members of Serratia marcescens, further confirmed this result. So it was named Serratia marcescens NS-17.2. Two red pigments, F1 and F2, produced by the strain Serratia marcescens NS-17 was separated and purified by column chromatography and thin layer chromatography. The TOFMS analysis suggested that [Mf1+H]=324.2086 and [Mf2+H]=340.2018, the accurate molecular weights suguested that molecular formulas of F1 and F2 were C20H25N3O and C20H25N3O2 respectly. The molecular structures were charactored via FT-IR and NMR analysis.3. Single factor experiments were carried out to analyze the effects of several factors on production of PG, the factors were as follow:Carbon sources, nitrogen source, KCL, NaCl, tween-80, soybean oil, incipient pH of culture medium, inoculum size, volume of broth, cultivation temperature, rotational rate and incubation time. Response surface analysis was used to evaluate the interaction of tween-80, soybean oil, volume of broth and rotational rate. The PG producing condition of Serratia marcescens NS-17 was optimized. Under this optimized conditions, maltose 6g/L, peptone 12g/L, NaCl 1g/L, KCL 2g/L, tween-80 1.2%, soybean oil 4.5%, incipient pH of culture medium 8.0, inoculum size 1.5%, volume of broth (250mL conical flask), rotational rate 210rpm, cultivation temperature 30℃, incubation time 32h, the OD535 per milliliter broth after fermentation reached 16.24, and has increased 401.2% than that of the original broth.