Detection of respiration changes inside biofilms with microelectrodes during exposure to antibiotics

In order to evaluate the influence of antibiotics on the respiration of subpopulations in biofilms, dissolved oxygen microelectrodes were used to determine the oxygen concentration inside E. Coli biofilms. Based on the results, the oxygen consumption rate varying with depth in the biofilms was calculated before and after the treatment with antibiotics. For both ceftriaxone sodium and chloramphenicol, significant attenuation of oxygen consumption was identified when the system reached steady state. However, by monitoring the oxygen concentration change induced by ceftriaxone sodium, an increased oxygen consumption rate and a shortened oxygen penetration depth were identified in the first few hours, which indicated the accelerated respiration of the subpopulation. Followed by cellular death, the induced respiration acceleration seems to be part of the action mechanism of ceftriaxone sodium. Compared to the planktonic cells, the biofilms showed much higher tolerance to ceftriaxone sodium, which may be attributed to the extended hypoxic zone induced by the accelerated respiration.