A magnetic force microscope (MFM) was used to image topography and magnetic forces from a chain of submicron single magnetic domain particles produced by and contained in isolated magnetotactic bacteria. The noncontact magnetic force microscope data were used to determine a value for the magnetic moment of an individual bacterial cell, of order 10−13emu, consistent with the average magnetic moment of bacteria from the same sample, obtained by superconducting quantum interference device magnetometry. The results represent the most sensitive quantification of a magnetic force microscope image to date. ©1995 American Institute of Physics.