Study On Mutagenesis,Fermentation,Structure And Properties Of Products Of Antarctic Erythrochrome Fungi

Pigment is the first sensory standard of food.The application of synthetic pigments is gradually limited,because of its harmfulness of chemical substances.So the natural pigments have broad development prospects.Natural pigment which derived from microbe was attracted more and more due to its low cost,fast fermentation speed,and less influence on origin and climate conditions.In this experiment,we mutated a purple-red pigment-producing fungus（Geomyces sp.wnf-A）which isolated from Antarctic samples.By ultraviolet mutagenesis,we successfully increased its output and named it as Geomyces sp.wnf-15B.Geomyces sp.wnf-15B was determined as a member of Geomyces based on colony morphologic characteristics,microscopic morphology and the phylogenetic analysis of ITS,and its optimum growth temperature was between 10-15℃.We analyzed the structure of Antarctic red pigments by using UV、HPLC、¹HNMR、¹³CNMR、NMR and others,and found its mother nucleus structure was cyclic ketones which was same as monascus red pigment.We studied the producing pigment abilittis of Geomyces sp.wnf-15B,and determined that the optimum fermentation conditions in 3L triangular flask were as inoculation amount 7%and shaking speed 125 r/min.In 5L triangular flask,the optimum fermentation conditions were as inoculation amount 7%and shaking speed 140r/min.We optimized the aeration rate and fermentation medium of pigment-producing strains in 5L multi-fermentor,and determined the stable fermentation conditions,in order to further improved the production of pigment.We compared Geomyces sp.wnf-15B with cochineal red pigment on the pH stability,the adaptabilities of starch and dextrin,the color reaction,fluorescence reaction and ash residue.We found that the pH adaptability of Antarctic red pigments was higher than that of cochineal red pigments.In the environment of pH 2-5,cochineal red pigments precipitated obviously,OD₅₂₅25 value decreases dramatically,but Antarctic red pigments precipitated less,OD₅₂₅25 value decreases slightly.In the environment of pH6-11,both pigments were relatively stable.In the environment of pH 12-13,the OD₅₂₅value of cochineal red pigments decreases significantly,but the absorption wavelength of Antarctic red pigments changed to orange system.This experiment showed that the Antarctic red pigment showed the main advantage of acid stability.In the comparisons of other properties,the Antarctic red pigment also had advantages over the cochineal red pigment...