Fig. 7

Transmission electron micrograph of cobalt oxide nanoparticles (Co₃O₄) synthesized using Microbacterium sp. MRS-1. a Large pentagon-like crystalline cobalt oxide nanoparticles were bound on the cell wall at one pole of the bacteria under cobalt containing environment for 24 h. b Cobalt oxide nanoparticles (Co₃O₄) were synthesized and accumulated all over the bacterial cell. Arrow indicates the synthesized cobalt nanoparticles around the bacterial cell, and it can be clearly seen that the cobalt nanoparticles were deposited as thick layer on the cell wall of the bacteria for 48 h to the metal environment. c Fully mineralized bacterium encrusted with cobalt oxide nanoparticles observed at 72 h of exposure to the metal environment