Research Highlight

Guinea bugs

doi:10.1038/nindia.2009.156 Published online 17 June 2009

An Indian research team has captured pictures of how live bacterial cells changes shape and properties when exposed to metal ions1.

The researchers isolated a marine bacterium known as Brevibacterium casei from the coast of Arabian Sea, grew it in a special chemical broth and fed it with cobalt acetate. The bug underwent changes in elastic properties and cell surface morphology while synthesising cobalt oxide nanocrystals and being exposed to cobalt ions.

The events were studied using atomic force microscopy (AFM), which can image the surface of living cells down to the molecular level resolution in real time. The AFM uses a delicate and sophisticated tip to study the bug sample. The tip was moved closer (a few atomic distances) and away (few nanometers) from the sample to study the bug's stiffness and adhesive properties.

The adhesive force and adhesive energy was enhanced during the biosynthesis after the exposure of the bacterial cells to the metal ions. This happens due to an increasing amount of exopolysaccharide and other biomolecules at the surface as the microbial reaction proceeds.

This proves to be a great tool for the real-time observation of the effects of drugs, biomolecules, metal ions and nanoparticles on cell physiology in their natural environment, the researchers say.


  1. Kumar, U. et al. Real-Time Nanomechanical and Topographical Mapping on Live Bacterial Cells - Brevibacterium casei under Stress due to their Exposure to Co2+ Ions during Microbial Synthesis of Co3O4 Nanoparticles. J. Phys. Chem. B. 113, 7927-7933 (2009) | Article |