Multimodal imaging reveals a small subpopulation of Deinococcus radiodurans exhibiting correlated low superoxide radical levels with extraordinary silver ion metabolism

Abstract

Abstract A polyvalent strategy has recently been assumed to be adopted by Deinococcus radiodurans that can generate various resistance against many different detrimental sources of oxidative damage (e.g., reactive oxygen species, heavy metal ions, and ionizing radiation). On this basis, investigating more than one restorative metabolic activities and their interrelation of the very same entities of D. radiodurans is of great significance for exploring its polyextremophile nature, which will be insightful for obtaining fundamental generic insights into life sustainability. Herein, we apply mainly fluorescence microscopy and back‐reflection microscopy to visibly assess the respective activities of superoxide radical generation and silver ion metabolism for individual D. radiodurans. Strikingly, only a minority (< 20%) of the bacteria, which show low superoxide radical levels, is revealed to exhibit considerable formation of silver nanoparticles, while those containing more superoxide radicals, all show minimum silver ion metabolism. The discovery of the strong negative correlation for the small subpopulation between the two visualized different metabolic activities not only provides direct experimental evidence in terms of bacterial functionality for the inferred survival regime of the extreme microbe, but also suggests a new way of chemically examining biology from the perspective of interfunctional relationship. Keypoints The use of back‐reflection microscopy allows the discovery of a small subpopulation of Deinococcus radiodurans exhibiting extraordinary silver ion metabolism. Combining fluorescence microscopy and bright‐field microscopy, we further show the subpopulation all contain correlated relatively low levels of superoxide radicals. The findings from the angle of exploring interfunctional relationship directly support the polyvalent strategy currently proposed for the polyextremophile for survivals against various sources of oxidative damage.

Keywords

• Deinococcus radiodurans
• extremophile
• heavy metal metabolism
• optical microscopy
• oxidative damage
• reactive oxygen species