As nanoparticle use in industrial applications and consumer goods continues to increase, the need grows to understand the potential impacts of these particles on organisms in the environment. To understand the interaction between nanoparticles and bacterial cell surfaces at a molecular level, we used cell-wall mutants of the model Gram-positive bacterium Bacillus subtilis to test the hypothesis that particular cell surface components govern these interactions. The three strains employed differed in the composition of their wall teichoic acid chains (WTA), prominent negatively charged surface structures. Minimal differences were measured between the toxicities experienced by these mutants upon exposure to cationic-functionalized gold nanoparticles (MPNH2-AuNPs). However, fluorescence assisted cell sorting showed that the mutant with only d-alanine moieties on the WTAs experienced interacted with MPNH2-AuNPs to the largest extent, demonstrating the crucial role WTA construction plays in dictating interactions with cationic nanoparticles. Analysis of the surface potentials of the three strains demonstrated that the mutant with only d-alanine moieties on the WTAs had the most anionic character, suggesting that the effect of WTA structures on the bacterial-nanoparticle interaction is primarily mediated through electrostatics.

Identification of Gram-positive bacterial cell wall components responsible for interactions with cationic nanoparticles

253rd National Meeting (2017)

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