Zare Mohammad-Reza, Amin Mohammad-Mehdi, Nikaeen Mahnaz, Bina Bijan, Rahmani Ayat, Hemmati-Borji Saeedeh, Rahmani Hasan
Fasa University of Medical Sciences, Fasa, Iran.
Environ Monit Assess. 2015 May;187(5):263. doi: 10.1007/s10661-015-4457-y. Epub 2015 Apr 17.
One of the most important factors that affect the operation efficiency of sequencing batch reactor (SBR) technology is bacterial viability and biomass activity. The acute toxicity of three heavy metals to four dominant strains of sequencing batch reactor (Pseudomonas, Aeromonas, Enterobacter, and Bacillus) was investigated using a resazurin bioassay. After exposing the bacterial strains to soluble compound of Hg, Cd, and Pb, at more than five selected concentrations, the median effective concentration (EC50) and the mortality rate values were calculated. Large differences were observed in sensitivities of the four bacterial strains to the metals. Pseudomonas showed the highest sensitivity for Cd (EC₅₀ = 0.06 μmol/L) and Hg (EC₅₀ = 11.75 μmol/L), while Aeromonas showed the highest sensitivity for Pb (EC₅₀ = 48.27 μmol/L). Considering the EC50 test results, it was concluded that Pseudomonas and Aeromonas are excellent and reliable bioindicators for assessing the toxicity of water and wastewaters polluted by Cd, Hg, and Pb. The rapidity (30 min) and simplicity of the resazurin bioassay procedure enable this enzymatic test to be used in toxicity assessment of small and decentralized wastewater treatment plants (WWTPs).
影响序批式反应器（SBR）技术运行效率的最重要因素之一是细菌活力和生物量活性。使用刃天青生物测定法研究了三种重金属对序批式反应器的四种优势菌株（假单胞菌属、气单胞菌属、肠杆菌属和芽孢杆菌属）的急性毒性。将这些细菌菌株暴露于汞、镉和铅的可溶性化合物中，在五个以上选定浓度下，计算半数有效浓度（EC50）和死亡率值。观察到这四种细菌菌株对这些金属的敏感性存在很大差异。假单胞菌属对镉（EC50 = 0.06 μmol/L）和汞（EC50 = 11.75 μmol/L）表现出最高敏感性，而气单胞菌属对铅（EC50 = 48.27 μmol/L）表现出最高敏感性。考虑到EC50测试结果，得出结论：假单胞菌属和气单胞菌属是评估受镉、汞和铅污染的水和废水毒性的优秀且可靠的生物指示物。刃天青生物测定法的快速性（30分钟）和简便性使得这种酶促测试能够用于小型分散式污水处理厂（WWTPs）的毒性评估。
