EFFECT OF HIGH MAGNETIC-FIELD ON THE GROWTH OF BACILLUS-SUBTILIS MEASURED IN A NEWLY DEVELOPED SUPERCONDUCTING MAGNET BIOSYSTEM

A new superconducting magnet biosystem (SBS) has been developed, which can provide a magnetic field of 0.5-7 T, where biological reactions c an be conducted under temperature-controlled conditions. The aerobic g rowth of a bacterium, Bacillus subtilis MI113, was investigated under homogeneous (7 T) and inhomogeneous (5.2-6.1 T) magnetic fields in a s haken culture. In the stationary phase, the cell number in an inhomoge neous magnetic field was about twofold higher than that of the referen ce, indicating that the magnitude of the decrease in the cell number w as reduced by the high magnetic field. The slower decline in the cell number in a magnetic field was due to the slower death rate of the veg etative cells. The inhibition of spore formation from vegetative cells was also observed in a magnetic field, which was reflected by the red uced activity of aikaline phosphatase. Genetically transformed B. subt ilis MI113 (pC112) produced a higher concentration of a lipopeptide an tibiotic, surfactin, in the stationary phase in an inhomogeneous magne tic field due to the higher cell number of the transformant in the mag netic field. (C) 1997 Elsevier Science S.A.