Study on Toxicity of Seven Manufactured Nano Particles and Two Phenolic Compounds to Bacteria Vibrio fischeri Using Homemade Luminometer

Abstract

Acute toxicity of nano SiO₂, ZnO, MCM-41 (Meso pore silica), Cu, multi-walled carbon nanotube, single walled carbon nanotube, Fe (coated) and two phenol derivatives (hydroxyphenol and 4-aminophenol) to bacteria Vibrio fischeri by bioluminescence inhibition test, using a homemade luminometer, was evaluated. The values of the nominal effective concentrations, causing 20 % and 50 % inhibition of bioluminescence, using two mathematical models, Weibull and gamma at two times of 5 and 30 min were calculated. The results of each model were compared using linear regression. Luminometer was designed with photomultiplier detector. Luminol chemiluminescence reaction was carried out for the calibration graph. In the linear calibration range, the correlation coefficients and coefficient of variation were 0.988 and 3.21 % respectively, which demonstrate the accuracy and reproducibility of the instrument that are suitable. The important part of this research depends on how to optimize the best condition for maximum bioluminescence. The culture of Vibrio fischeri with optimal conditions in liquid media, were stirring at 120 rpm at a temperature of 23 to 26 ºC and were incubated for 24 to 48 h while solid medium was held at 18 ºC and for 48 h. Suspension of nanoparticles ZnO, after 30 min contact time to bacteria Vibrio fischeri, showed the highest toxicity while SiO₂ nanoparticles showed the lowest toxicity. After 5 min exposure time, the toxicity of ZnO was the strongest and MCM-41 was the weakest toxicant component. As can be known, this is the first investigation that evaluates the toxicity of nano materials SiO₂, MCM-41, Fe (Coated), multi-walled carbon nanotube, single walled carbon nanotube and phenolic components (hydroxyphenol and 4-aminophenol) to Vibrio fischeri by two mathematical models.