In order to study the morphology and composition of magnetosomes synthesized by two magnetococcus found at La Fe Dam and Calima Lake - Colombia, magnetotactic bacteria (MTBs) were separated by magnetic induction. MTBs and their magnetosomes were evaluated by energy dispersive x-ray spectroscopy (EDX) using transmission electron microscopy (TEM) and the size and shape of the nanocrystals were determined. Results revealed a high similarity between the magnetococcus under study, showing magnetite crystals with hexagonal-prismatic morphology and average length of 83 and 87 nm for crystals from La Fe and Calima respectively. By the size and shape factor, crystals were classified in the single domain magnetic range. Results obtained allow seeing future applications for biogenic magnetite in biotechnology and medicine.