Structural elucidation and stability of red pigment by a new strain of Serratia marcescens subsp. jx1

The red pigment,a kind of secondary metabolites,was produced by a new strain of Serratia marcescens jx1,which was screened in our laboratory.The red pigment was extracted and purified by using acetone.The obtained red pigment was identified as prodigiosin by UV/vis spectroscopy,IR and LC/MS.The effects of light,temperature,pH,metal ions,preservatives,antioxidants,reducing agents,as well as food composition on the stability of the red pigment were evaluated.The results showed that the red pigment belongs to the fat-soluble pigment.The main component is prodigiosin.The maximum absorption peak was at 535 nm in acidic environment,and its color value was higher than 250.Direct sunlight caused pigment to bleach,and no significant change was observed in pigment solution when temperature was lower than 100℃.Inorganic ions(such as Na+,Zn2+,Mg2+),oxidant H2O2,sucrose,salt,citric acid and low concentration of sodium benzoate(0.05 mol·L-1) had little effect on the stability of the pigment.Reducing agent Na2SO3,metal ions Fe3+,Ca2+,preservatives sodium benzoate were able to destroy the stability of the red pigment.