Nanoparticles affect bacterial colonies' optical diffraction patterns

It is increasingly being accepted that bacteria are able to alter their shape/colony pattern in response to adverse environmental conditions. Morphological adaptation of bacteria is known as one of their defence mechanisms against environmental stress/variations. As nanoparticles (NPs) have a unique capacity to induce a wide range of stresses to bacteria, we hypothesized that such NPs can affect the bacterial colony pattern. To test this hypothesis, we incubated a series of superparamagnetic iron oxide nanoparticles (SPIONs) with different physicochemical properties with bacterial colonies and probed the colonies' diffraction patterns by laser. The diffraction patterns of Escherichia coli, Lactobacillus rhamnosus, and Staphylococcus aureus colonies were recorded using a laser. Our results revealed the formation of distinct bacterial diffraction patterns in response to SPIONs with various concentrations and surface chemistries. Our results may pave the way toward the development of new optical approaches for the high-throughput screening of bacterial-NPs/drugs interactions.