Qu Xiaolei, Xiao Lin, Zhu Dongqiang
State Key Laboratory of Pollution Control and Resource Reuse, and School of the Environment, Nanjing University, Jiangsu 210093, China.
J Environ Qual. 2008 May 2;37(3):824-9. doi: 10.2134/jeq2007.0236. Print 2008 May-Jun.
Surface and subsurface contamination with nitroaromatic compounds (NACs) has drawn considerable attention, and biosorption may play an important role in the fate and transport of these compounds in the environment. We studied the sorption of polar 1,3-dinitrobenzene (DNB) as a representative NAC and 2,6-dichlorobenzonitrile and nonpolar phenanthrene and 1,2,4,5-tetrachlorobenzene from the aqueous phase to two common bacteria, gram-negative Escherichia coli and gram-positive Bacillus subtilis. Sorption of DNB is highly nonlinear and is well described by the Langmuir model and shows the highest capacity among all tested solutes (up to 2.4% of E. coli biomass and 7.6% of B. subtilis biomass by weight) despite the lowest solute hydrophobicity. These results indicate that strong specific sorptive interactions exist between DNB and bacterial surfaces. We propose a mechanism of n-pi electron-donor-acceptor interactions between the oxygen electron pairs of deprotonated carboxyl groups (electron donors) of bacterial surfaces and DNB (electron acceptor). Biosorption of DNB increases with deprotonation of functional groups as pH increases, which rules out hydrophobic effects and H-bonding as major sorption driving forces because they are both favored by protonation of functional groups as pH decreases.
硝基芳香族化合物（NACs）对地表和地下的污染已引起了广泛关注，生物吸附可能在这些化合物在环境中的归宿和迁移过程中发挥重要作用。我们研究了作为代表性NAC的极性1,3 - 二硝基苯（DNB）、2,6 - 二氯苯腈以及非极性菲和1,2,4,5 - 四氯苯从水相到两种常见细菌——革兰氏阴性大肠杆菌和革兰氏阳性枯草芽孢杆菌的吸附情况。DNB的吸附具有高度非线性，可用朗缪尔模型很好地描述，并且在所有测试溶质中显示出最高的吸附容量（按重量计，高达大肠杆菌生物量的2.4%和枯草芽孢杆菌生物量的7.6%），尽管其溶质疏水性最低。这些结果表明DNB与细菌表面之间存在强烈的特异性吸附相互作用。我们提出了一种细菌表面去质子化羧基的氧电子对（电子供体）与DNB（电子受体）之间的n - π电子供体 - 受体相互作用机制。随着pH值升高，DNB的生物吸附随着官能团的去质子化而增加，这排除了疏水作用和氢键作为主要吸附驱动力，因为随着pH值降低，它们都受到官能团质子化的促进。
