Intracellularbiogeniccrystalssynthesizedbyfreshwater� magnetotacticbacteria� (MTBs)� fromLaFeDamand� CalimaLake� -� Colombiawereseparatedfrom� water/sedimentsamplesusingamagneticfieldof�6�Gauss.� Bacterialconcentrateswereobservedbytransmission� electronmicroscopy� (TEM)� andanalyzedwithrayX� microdiffraction�(microXRD),�Fouriertransformedinfrared� spectroscopy� (FTIR)� andmagneticmeasurements.� Magnetosomesweremeasuredandanalyzedwith� EDX/TEM�(EnergydispersiveX�-�rayanalysis).�Results� showedmagnetitecrystalswithcuboctahedral,�hexagonal� prismaticandbulletmorphology;� mostcrystalswere� classifiedinthesingledomainmagneticstate,� withan� averagelengthsmallerthan�100�nm.�SampleswithMTBs� weresaturatedinafieldcloseto� 100� mT,� showing� ferrimagneticbehavior.� Theseresultsopenthepathto� othersstudieswithMTBsinColombiathatcouldleadto� findfutureapplicationsformagneticbiomineralsin� nanobiotechnologyandmedicine.�