| Perylenequinones represented by hypocrellins is a kind of photosensitive pigment, widely distributed in nature. These compounds can be obtained either through the solid or liquid fermentation of Shiraia bambusicola fungus or through the direct extract of natural tabasheer stroma. However, the limitation of the natural resources make it is unable to meet the demand of industrial production. Thus, the exploitation of biological fermentation to produce perylenequinones becomes the research focus.Shiraia sp. Slf14, which can produce hypocrellins, is a novel endophytic fungus isolated by our research group from Huperzia serrata in China. In this paper, we applied both the single-factor method and orthogonal experiment to optimize the fermentation condition for Shiraia sp. Slf14 to improve the perylenequinones production. Moreover, to probe the mechanism of perylenequinones synthesis, we control the content of perylenequinones components during fermentation via modifying the medium composition. These results were able to lay the foundation for the large-scale fermentation of perylenequinones production especially hypocrellin A(HA) in the future. The key findings of this study are as follows.(1) Established a method for determining the content of each seperate component from perylenequinones mixture. The method is adopted the YMC-Triart C18 chromatographic column(5.0 ?m, 4.6 mm×250 mm) for seperation and eluted with the mixture of acetonitrile and three distilled water(volume ratio of 70:30). The elution condition is that of flow rate 1.0 mL/min, column temperature 25?, detection wavelength 460 nm and the sample inoculate size 20 uL. The results indicated that the five compounds showed a good linear relationship between the peak area and the concentration. At the same time through the precision and repeatability experiment showed that this method was able to separate and detect the HA, hypocrellin B(HB), elsinochrome A(EA), elsinochrome B(EB) and elsinochrome C(EC) from the perylenequinones mixture simultaneously.(2) Investigation the influence of different carbon source, nitrogen source and inorganic salts on the perylenequinones produced by Shiraia sp. Slf14. Results showed that both the fructose and the Jerusalem artichoke powder were able to enhance the production of perylenequinones and meanwhile these two carbon source enable to improve the productivity of HA and EA respectively. The proportion of HA in the perylenequinones was about 49.62% when the initial concentration of fructose was 60 g/L in the culture. Analogously, the yeast extract enhanced the generation of HA, EA while the sodium chloride elevated the productivity of HA and EB, respectively. The optimized medium of Shiraia sp. Slf14 for perylenequinones production which was determined through the orthogonal experiment was that potato 200 g/L, fructose 60 g/L, yeast extract 5 g/L and sodium chloride 5 g/L. As a result, the total productivity of perylenequinones was 2567.30 mg/L which is 8.5 fold of control.(3) Through a single factor experiment, this paper studies the influence of different amino acids and vitamins on the perylenequinones production by the Shiraia sp. Slf14 fermentation. Results show that eight amino acids(arginine, aspartate, phenylalanine, glycine, glutamine, lysine, valine and alanine) were all able to enhance the production of perylenequinones and HA significantly.While vitamin B9 and B5 both have the capable of improving the production of perylenequinones by Shiraia sp. Slf14. |
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