The introduction of various iron-chelating agents to the Magnetospirillum magneticum strain AMB-1 bacterial growth medium stimulated the growth of M. magneticum strain AMB-1 magnetotactic bacteria and enhanced the production of magnetosomes. After 7 days of growth, the number of bacteria and the production of magnetosomes were increased in the presence of iron-chelating agents by factors of up to similar to 2 and similar to 6, respectively. The presence of iron-chelating agents also produced an increase in magnetosome size and chain length and yielded improved magnetosome heating properties. The specific absorption rate of suspensions of magnetosome chains isolated from M. magneticum strain AMB-1 magnetotactic bacteria, measured under the application of an alternating magnetic field of average field strength similar to 20 mT and frequency 198 kHz, increased from similar to 222 W/g(Fe) in the absence of iron-chelating agent up to similar to 444 W/g(Fe) in the presence of 4 mu M rhodamine B and to similar to 723 W/g(Fe) in the presence of 4 mu M EDTA. These observations were made at an iron concentration of 20 mu M and iron-chelating agent concentrations below 40 mu M.