Study type: Medical/biological study (experimental study)

Effect of high magnetic field on the growth of Bacillus subtilis measured in a newly developed superconducting magnet biosystem med./bio.

By: Nakamura K, Okuno K, Ano T, Shoda M
Published in: Bioelectrochem Bioenerg 1997; 43 (1): 123-128
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Aim of study (acc. to author)

To investigate the effects of inhomogeneous (5.2-6.1 T) and homogeneous (7 T) high magnetic fields on the aerobic growth and spore formation of the bacterium Bacillus subtilis.

Endpoint

Exposure

Exposure Parameters
Exposure 1:
Exposure duration: continuous for 12, 18, 24, 30, 36, 48 and 72 h
Exposure 2:
Exposure duration: continuous for 12, 18, 24, 30, 36, 48 and 72 h

Exposure 1

Main characteristics
Frequency
Type
Exposure duration continuous for 12, 18, 24, 30, 36, 48 and 72 h
Additional info homogeneous magnetic field
Additional info Homogeneous magnetic field exposure Reference article: K.Ouda, K.Saito, T.Kamikado, S.Ito, K.Matsumoto, K.Okuno, K.Tsuhiya, T.Ano and M.Shoda. New 7 T superconducting magnet system for bacterial cultivation, Cryogenics, 35 (1995) 41-47.
Exposure setup
Exposure source
Setup 10 ml suspension was placed into two conical flasks and positioned in the magnet and the reference.
Additional info An incubator as a reference was covered with a magnetic shield, a double-walled cylindrical shell of Permalloy, in which the stay field was reduced to below the level of geomagnetic field strength. A ±0.5% deviation of the field homogeneity was observed in an area of 16 cm in diameter and 20 cm in length in the bore. This area was the homogeneous region, outside that region, a gradient with a slope of 23 T/m was formed.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 7 T - measured - at the center of the bore of the magnet
Measurement and calculation details

The magnetic field was measured by a flux meter.

Exposure 2

Main characteristics
Frequency
Type
Exposure duration continuous for 12, 18, 24, 30, 36, 48 and 72 h
Additional info inhomogeneous magnetic field
Additional info Inhomogeneous magnetic field
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 5.2 T - measured - to 6.1 T

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

No clear difference in cell number was observed between the homogeneous magnetic field exposure and the reference. The cell number under inhomogeneous magnetic field conditions was about twofold higher than that in the reference after 72 h. The results further suggests that the inhomogeneous magnetic field inhibits spore formation. The activity of alkaline phosphatase was significantly suppressed under inhomogeneous magnetic field conditions. Protease activity was also reduced, but not in the degree the alkaline phosphatase was. Under inhomogeneous magnetic field conditions the cell number of recombinant bacteria was larger than the reference, which was reflected in an enhanced production of the antibiotic surfactin. This leads to the suggestion that the magnetic field does not affect the stability of the plasmid.

Study character:

Study funded by