Application Of Luminous Bacteria In Toxicity Testing And Biological Effects On Nanomaterials

Recently, much attention has been focused on the biological effects of nanomaterials which were widely used in many fields. It involved biological effects of nanomaterials on mice, fish, algae and cell more than microbial effects. This paper discussed the biological effects of nanomaterials based on luminous bacteria by the establishment and application of toxicity testing methods, provided credible data and conclusions for the safety evaluation of nanomaterials. Based on the above subjective, this paper obtained the following results:It firstly established methods for toxicity testing of nanomaterials which were measured by Photobacterium phosphoreum T3, Photobacterium phosphoreum 502 and Vibrio qinghaiensis Q67, respectively. And sensitivity of three luminescent bacteria on nanomaterials was investigated and compared. The results indicated that the toxicity of nano-ZnO was the highest, the 15-min EC50 (mg/L) value of nano-ZnO, nano-TiO2, nano-SiO2 was 0.80,327, 570 mg/L (T3); 0.38,280,657mg/L (502) and 0.70,>1000,>1000 mg/L (Q67), respectively. Suspensions of nano-TiO2 and nano-SiO2 were not observed toxic effect on Vibrio qinghaiensis Q67 at 1000 mg/L. Two nano-Ag dispersions were measured by Photobacterium phosphoreum 502 and the 15min-EC5o value was 1.3 mg/L (<5 nm),0.97 mg/L (20 nm-30 nm), respectively. Luminous inhibition effect of nano-Ag on the bacteria was quite obvious. Photobacterium phosphoreum 502 exhibited better sensitivity than others in the testing toxicity. It could be widely used in toxicity testing of different nanomaterials.Secondly, it tested biological effects of the same kind of nanomaterials with different particle sizes by Photobacterium phosphoreum 502 combining high throughput screening method with microplate detection technology. 15-min EC50 value of nano-ZnO were 0.33 mg /L (30 nm),0.56 mg/L (50 nm),0.61 mg/L (100 nm) and 0.63 mg/L (500 nm).15-min EC50 values of nano-CuO were 67.2 mg/L (50 nm) and 69.8mg/L (100 nm).15-min EC50 values of silver bactericide were 6.94 mg/L (VK-T09),4.41 mg/L (VK-T08). It showed different biological effects with different size of nanomaterials. The smaller the particle sizes of the same nanomaterial, the greater the light inhibition.Finally, it tested inhibition effect of nanomaterials on the growth of bacterial colony by plat colony-counting method. The results showed that nano-Ag dispersion, nano-ZnO, nano-NiO in a certain range of concentration significantly inhibited the colony growth of luminous bacteria. Its order was:Nano-Ag dispersion> nano-ZnO nano-NiO> nano-TiO2> nano-SiO2. It also showed slightly lower growth inhibition for nano-Ag (<5nm) dispersion than nano-Ag (20-30nm) dispersion and for silver-zirconium phosphate than Ag-carrying antibacterial. Growth inhibition effect and high-throughput testing of Ag-carrying antibacterial were in good agreement.In short, toxicity testing of nanomaterials by luminous bacteria was a rapid, effective and economical method. It had far-reaching significance for biological effects of nanomaterials especially in high throughput screening.