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研究目的（著者による）
The effects of exposure of alpha-hemolytic streptococcus bacteria to a 50 Hz magnetic field on cell growth and mannatide production in view of a use in biotechnology should be investigated.
詳細情報
Mannatide is a glyco-peptide with a variety of biologically active compounds, which is used in clinical medicine, poultry feed, and functional foods. Streptococcus bacteria can create mannatide. The aim of the study was to find optimum parameters (magnetic flux density, exposure duration and exposure time period) for the endpoints, so cells were divided into different groups. For determination of optimum magnetic flux density: exposure to the magnetic field for 4 h (4-8 h of incubation) at 1) 0.1 mT, 2) 0.4 mT, 3) 0.6 mT, 4) 0.9 mT, 5) 1.2 mT and 6) 1.5 mT. For determination of optimum exposure duration: exposure to a 0.6 mT magnetic field for 7) 2 h, 8) 4 h, 9) 6 h, 10) 8 h, 11) 12 h and 12) 16 hours from the beginning of incubation. For determination of optimum exposure time period: exposure to a 0.6 mT magnetic field for 4 hours in the period 13) 0-4, 14) 4-8, 15) 8-12, 16) 13-17, 17) 17-21 and 18) 21-25 hours of incubation time. For each exposure group, a separate control group was used.
影響評価項目
cell growth and mannatide production of alpha-hemolytic streptococcus bacteria
exposure system consisted of five pairs of cylindrical coils wrapped up using magnetic shielding materials; coils had the following parameters: outer diameter of 120, 126, 132, 138 or 144 mm, inner diameter of 100 mm, wire length of 600 mm, number of threads was 1800, 2400, 3000, 3600 or 4200, diameter of wire of 2 mm; the coils of each pair were used for replicated samples; ten rotating sample shake flasks were placed on a nonconductive stand in the middle of each coil; sample temperature was maintained at 37°C ± 1°C
In determination of the optimum magnetic flux density, the highest significant increase in cell growth and mannatide production was found in group 3 (0.6 mT) compared to the control group, so this magnetic flux density was used in further tests. In determination of the optimum exposure duration, the only duration which resulted in both, a significant increase in cell growth and mannatide production compared to the control group, was group 8 (4 hours), so this duration was used for further tests. In determination of optimum exposure time period, the highest significant increase in cell growth was found in group 14 (4-8 hours of incubation) and the highest significant increase in mannatide production was observed in group 15 (8-12 hours of incubation). Because of giving priority to mannatide production, group 15 was considered the optimum. In a last step, the cell growth and mannatide production kinetics were observed in group 15 over an incubation time of 35 hours. Maximum cell growth and mannatide levels were increased by 10.7 % and 14.0 % at 25 and the 27 hour of incubation, respectively, in exposed cells compared to the control group. The authors conclude that exposure of alpha-hemolytic streptococcus bacteria to a 50 Hz magnetic field might temporarily enhance cell growth rate and mannatide production rate.
