This is an in-depth theoretical and experimental study explaining the formation of colonial patterns in the macroscopic growth of bacterial colonies under its own E&H electric and magnetic fields. Recently there has been more and more work on the formation of bacterial colony patterns but they only consider the case where E and H are external to the compact bacterial colonies whereas in this article we consider the growth of hollow bacterial colonies in the form of two concentric circles under its own intrinsic fields E and H. In addition, we offer an iron rich agar food dish which has been shown to be effective in producing a considerable part of bacterial cells rich in iron compounds and magnetic nano-needles called magnetotactics. This allows the study of the spatial formation and temporal evolution of growing colonial patterns in addition to the electrical and magnetic properties of the bacterial cells themselves. Theoretical and experimental analysis elucidates that macroscopic growth can be classified into two main phases, the early onset phase and the subsequent intense second phase. In the first phase, colonial growth is a situation dominated by diffusion in a boundary value problem while in the dense phase the colony grows outward through radial branches following the intrinsic E field (which repel each other) and divides into circulars following the intrinsic H field. The intrinsic E lines of the colony are radial rays while the H lines are closed concentric circles perpendicular to E. When the Agar is rich in iron compounds, the so-called magnetotactic bacteria form considerably during the second intense phase in two opposite orientations and follow the circles of the H field in the parallel or antiparallel direction. At some point the magnetotactic bacteria separate or split from the radially negatively charged bacteria and follow the circular magnetic field in an interesting macroscopic phenomenon which is the subject of this article. In other words, the theory predicts that in the second intense phase, the negatively charged electrosensitive bacterial cells should travel along the E field lines radially outward while the part of the magnetotactical bacterial cells separate and follow the H field along concentric circles in a macroscopic phenomenon which should be observable experimentally. The present study is expected to effectively contribute to the theory and design of future bacterial batteries as a renewable energy source.