Bacterial toxicity comparison between nano- and micro-scaled oxide particles

摘要

Toxicity of nano-scaled aluminum, silicon, titanium and zinc oxides to bacteria (Bacillus subtilis, Escherichia coli and Pseudomonas fluorescens) was examined and compared to that of their respective bulk (micro-scaled) counterparts. All nanopartides but titanium oxide showed higher toxicity (at 20 mg/L) than their bulk counterparts. Toxicity of released metal ions was differentiated from that of the oxide particles. ZnO was the most toxic among the three nanopartides, causing 100% mortality to the three tested bacteria. Al_2O_3 nanopartides had a mortality rate of 57% to B. subtilis, 36% to E. coli, and 70% to P. fuorescens. SiO_2 nanopartides killed 40% of B. subtilis, 58% of E. coli, and 70% of P. fluorescens. TEM images showed attachment of nanopartides to the bacteria, suggesting that the toxicity was affected by bacterial attachment. Bacterial responses to nanopartides were different from their bulk counterparts; hence nanoparticle toxicity mechanisms need to be studied thoroughly.