Relativistic jet phenomena are most often observed in the vicinityof black holes, where the surrounding plasma accretion plays animportant role in the formation of these jets. The presence of amagnetic field is crucial since it has a significant effect on theaccretive behaviour of a plasma. Primarily, the magnetic field linksthe central source with the ambient plasma and can be considered asa set of wires which can transport energy toward the black hole andaway by means of MHD waves. Moreover, the magnetic field is able tocollimate the plasma flow, which gives rise to a relativistic jetformation. To investigate the behaviour of a magnetized plasmaaccretion around a spinning black hole we use a string approach,which allows to depict the magnetized plasma as a set of magneticflux tubes/string. It turned out that the interaction of themagnetic flux tube with the spinning black hole leads to an energyextraction process, which is attended by a relativistic jetcreation. The influence of the reconnection process on the jetevolution leads to the formation of plasmoids, which move outwardfrom the central source and remove energy and angular momentum. Thisprocess can be repeated over and over and finally the jet structureis composed of a chain of plasmoids which propagate along the spinhole axis.