地球上所有生物的繁衍生息和进化都是在地磁场环境伴生中进行的。因此，认识地磁场对生物的影响是地球科学的重要研究内容。最近，美国出版的《生物物理学杂志》（Biophysical Journal）和《地质微生物学杂志》（Geomicrobiology Journal）杂志发表了中国科学院地质与地球物理研究所地球深部结构与过程研究室潘永信研究员与合作者在此研究领域的两篇论文,他们综合分子生物学、电子显微镜技术、岩石磁学等交叉学科手段，系统研究了趋磁细菌MYC-1的磁学性质和趋磁游泳特性。
研究表明，趋磁球菌MYC-1属于α-变形菌纲的一株新型趋磁细菌，它们在细胞内合成1条磁小体链，链的排列与细胞运动器官鞭毛具有一定的夹角；合成的磁小体为单畴磁铁矿。根据旋转磁场游泳行为计算获得单个细胞磁矩为1.8×10-15 Am2。他们发现无论是在直线场还是旋转场，MYC-1均为螺旋前进，而非直线运动，且随磁场强度增加，趋磁游泳速度（VM，平行磁场方向）降低，这项发现对趋磁细菌游泳速度随外场强度增加而单调增加的传统观点提出了挑战。研究结果反映出趋磁细菌与地磁场具有长期协同进化的特点，当磁场强度高于地磁场时趋磁游泳速度受到抑制，这为揭示地磁场对生物的影响、细菌矿化，以及认识生物的趋磁性质和磁导航具有重要科学意义。（生物谷Bioon.com）
生物谷推荐原始出处：
Biophysical Journal Volume 97 August 2009 986–991
Reduced efficiency of magnetotaxis in magnetotactic coccoid bacteria in higher than geomagnetic fields.
Pan Y, Lin W, Li J, Wu W, Tian L, Deng C, Liu Q, Zhu R, Winklhofer M, and Petersen N
Magnetotactic bacteria are microorganisms that orient and migrate along magnetic field lines. The classical model of polar magnetotaxis predicts that the field-parallel migration velocity of magnetotactic bacteria increases monotonically with the strength of an applied magnetic field. We here test this model experimentally on magnetotactic coccoid bacteria that swim along helical trajectories. It turns out that the contribution of the field-parallel migration velocity decreases with increasing field strength from 0.1 to 1.5 mT. This unexpected observation can be explained and reproduced in a mathematical model under the assumption that the magnetosome chain is inclined with respect to the flagellar propulsion axis. The magnetic disadvantage, however, becomes apparent only in stronger than geomagnetic fields, which suggests that magnetotaxis is optimized under geomagnetic field conditions. It is therefore not beneficial for these bacteria to increase their intracellular magnetic dipole moment beyond the value needed to overcome Brownian motion in geomagnetic field conditions.
