Breeding Of High-Yield Pigment Production Monascus And Studies On Pigments' Qualities

In last decades, pigments from natural sources have been subject of intense research, because of their safe use as natural food dye in replacement of synthetic pigments. Microbial colorants played a significant role because of its cost-effective and easy downstream engineering, and the Monascus pigment was one of them. People should pay more attention on the utilization of Monascus pigment with the continuously deepened on Monascus spp.In this study, a Monascus strain with high yield pigment production was isolated. To maximize the productivity of Monascus pigment, various parameters were studied in solid-stated fermentation, and the quality of pigment was also studied.(1)The strain was identified as Monasucus purpureus by morphological and ITS region sequence comparisons. It was named as Mp-41and pigment yield reached 4010 U/g. it was preservation in Chinese typical microorganism training center (CCTCC NO:209133). Accession number in GenBank of ITS region sequence was HQ659499.1. The patent application number was 200910102278.9.(2) To maximize the productivity of Monascus pigment, various parameters were studied in solid-stated fermentation. Three factors (initial moisture content, inoculum volume, fermentation time) were chosen for further study by a Box-Behnken design. By the point prediction tool of Design-Expert 7.0, the optimum values of the factors for maximum pigment production were determined:initial moisture content 44.81%, inoculum volume 2.65 mL, fermentation time 10.19 d. Under above optimized conditions the experimental result was 5340.4 U/g which agreed closely with the predicted yield.(3) The extraction technology of water-soluble pigment from red kojic rice was studied. On the basis of single-factor experiment, the response surface methodology was used to study the effects of ultrasonic time, material solvent ratio and ultrasonic wave power on the water-soluble pigment extraction. A quadric regression model for the water-soluble Monascus pigment concentration was established, and the optimum extraction conditions were obtained. It showed that all the three factors were playing the important roles to water-soluble pigment extraction. The optimum extraction conditions were as follows:ultrasonic time 20.6 min, material to solvent ratio 32.2:1, ultrasonic wave power730 W. Under such conditions, the water-soluble pigment concentration of the extract would reach the theoretical maximum 570.5 U/g.(4) The stability on pH, temperature, visible light and UV to pigments produced by Mp-41 was studied. By physical thermal degradation kinetics, the thermal degradation half-life of Mp-41 pigment was given. Meanwhile, under different wavelengths of visible light and different pH, the stability of the pigment is explored. The results show that when the pH is 6-9 tone stability, pigment color stays bright. With temperature increasing, half-life of pigment decreases and its stability lowers. After red light radiation, pigment can be saved at the highest rate. After blue light, it's at the lowest rate, similar to composite light. Pigments liquid are relatively stable under UV light.(5) The separation of Mp-41 pigment was carried out by TLC. The result showed that the optimum developing solvent was benzene:methanol:chloroform (30:10:10), and eight red bands, two yellow bands, an orange band and a purple band was obtained. Different concentrations of Monascus pigment, by means of the oxford cup method, acted on the Escherichia coli, Staphylococcus aureus, Candida albicans, Bacillus subtilis is to determine the antibiotic activity. The results showed that antibacterial activity to Staphylococcus aureus was stronger than to Bacillus subtilis and Candida albicans, next to Escherichia coli. With Gibberella fujikuroi, Fusarium oxysporum f.sp. momordicae, Fusarium oxysporum f.sp.cucumerinum, Sclerotium rolfsii, Alternaria solani as tested bacteria, the antibacterial activity of ethanolic extracts of Monascus-rice was determinated by growth rate method. The results showed that antibacterial activity to Alternaria solani (EC50=0.0433 mg/mL) and Sclerotium rolfsii (EC50=0.0747 mg/mL) was stronger than to Fusarium oxysporum f.sp.cucumerinum, next to Gibberella fujikuroi and Fusarium oxysporum f.sp. momordicae.