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研究目的（著者による）
The optimum parameters of exposure to a 50 Hz magnetic field for the production of yellow and red pigment by Monascus purpureus should be investigated in view of a biotechnological use.
詳細情報
Monascus is a traditional fermentation fungus and is used to produce secondary metabolites, which include, among others, the food pigments ankaflavin and monascine. The optimum parameters for exposure duration, magnetic flux density and exposure period should be determined. To determine the optimum exposure duration, cells were divided into the following groups: exposure to a 0.4 mT magnetic field for 1) 1 h, 2) 4 h, 3) 12 h, 4) 24 h, 5) 48 h, 6) 72 h and 7) 96 h. To determine the optimum magnetic flux density, cells were divided into these groups: exposure for 48 h to a magnetic flux density of 8) 0.05 mT, 9) 0.1 mT, 10) 0.25 mT, 11) 0.4 mT, 12) 0.6 mT, 13) 0.8 mT, 14) 1 mT. To determine the optimum exposure period, cells were divided into the following groups: exposure to a 0.4 mT magnetic field for 48 hours during the 15) 2nd-3rd day, 16) 4-5th day, 17) 5-6th day, 18) 6-7th day, 19) 8-9th day and 20) 10-11th day of cultivation. An additional control group was used for each test.
system consisted of five pairs of cylindrical coils (number of threads: 4200, 3600, 3000, 2400, 1800, respectively; outer diameter: 144, 138, 132, 126, 120 mm, respectively; inner diameter: 100 mm; length 600 mm; diameter of wire: 2 mm) wrapped up using magnetic shielding materials; 10 bottles with cells in culture medium were placed on a nonconductive stand in the center of the coils; sample temperature was maintained at 29 ± 1°C by a thermostat
Regarding the optimum exposure duration, the highest significant increase in yellow and red pigment production was found in group 5 (48 hours) compared to the control group. Regarding the optimum magnetic flux density, the highest significant increase in yellow and red pigment production was found in group 11 (0.4 mT) compared to the control group. Regarding the optimum exposure period, the highest significant increase in yellow and red pigment production was found in group 19 (8th-9th day) compared to the control group. In a final kinetics study with group 19 over 12 days of incubation time, it was found that the production of yellow and red pigments was significantly increased from the 8th to 11th day in exposed samples compared to the control group, which resulted in 65.4% and 59.2% increase in peak yield of yellow and red pigments, respectively. The authors conclude, that exposure of Monascus purpureus to a 0.4 mT 50 Hz magnetic field for 48 hours during the 8th and 9th day of exposure may enhance production of yellow and red pigment in fermentation processes.
