title: Change in broth culture is associated with significant suppression of Escherichia coli death under high magnetic field.
abstract: When Escherichia coli B was cultivated under an inhomogeneous magnetic field of 5.2-6.1 T, a significant 100,000-fold suppression of cell death was observed [Bioelectrochemistry 53 (2001) 149]. The limited magnetic field exposure for 12 h after logarithmic growth phase was sufficient to observe similar suppressive effects on cell death [Bioelectrochemistry 54 (2001) 101]. These results suggest some possible changes in either the medium or the cells during the magnetic field exposure. When the cell-free filtrate of the broth cultured under the magnetic field for 10 h and the cells of E. coli cultivated under the geomagnetic field for 30 h were mixed, and the mixture was subsequently cultivated under the geomagnetic field, the number of cells observed in the filtrate exposed to the high magnetic field was 20,000 times higher than that in the filtrate exposed to the geomagnetic field. When the cells cultivated under the magnetic field for 10 h and the cell-free filtrate of the broth culture exposed to the geomagnetic field were mixed, only a 50-fold difference in the number of cell between under the magnetic field and under the geomagnetic field was observed. This suggests that the filtrate of the broth culture exposed to the magnetic field is primarily responsible for the cell death suppression. It was also revealed that the small difference in pH of the filtrates of the broth culture between under the magnetic field and under the geomagnetic field was critical for the cell death suppression.
authors.affiliation: Chemical Research Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8503, Japan.
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Horiuchi
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Ishizaki
authors.forename: Kazumasa
authors.initials: K
authors.lastname: Okuno
authors.forename: Takashi
authors.initials: T
authors.lastname: Ano
authors.forename: Makoto
authors.initials: M
authors.lastname: Shoda
mesh_terms: D002453:Cell Cycle / Q000528:radiation effects; D016923:Cell Death / Q000187:drug effects / Q000528:radiation effects*; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects*; D003470:Culture Media / Q000378:metabolism / Q000494:pharmacology / Q000528:radiation effects*; D004574:Electromagnetic Fields; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects*; D006863:Hydrogen-Ion Concentration; D012016:Reference Values; D013045:Species Specificity; D014867:Water / Q000378:metabolism
chemical_list: D003470:Culture Media; D014867:Water