†Department of Microbiology, University of Tennessee, Knoxville, Tennessee 37996, United States.
‡Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee 37996, United States.
Environ Sci Technol. 2015 May 19;49(10):6214-21. doi: 10.1021/acs.est.5b00372. Epub 2015 May 6.
Bisphenol A (BPA), an environmental contaminant with weak estrogenic activity, resists microbial degradation under anoxic conditions but is susceptible to abiotic transformation by manganese dioxide (MnO2). BPA degradation followed pseudo-first-order kinetics with a rate constant of 0.96 (±0.03) min(-1) in the presence of 2 mM MnO2 (0.017% w/w) at pH 7.2. 4-hydroxycumyl alcohol (HCA) was the major transformation product, and, on a molar basis, up to 64% of the initial amount of BPA was recovered as HCA. MnO2 was also reactive toward HCA, albeit at 5-fold lower rates, and CO2 evolution (i.e., mineralization) occurred. In microcosms established with freshwater sediment, HCA was rapidly biodegraded under oxic, but not anoxic conditions. With a measured octanol-water partition coefficient (Log K(ow)) of 0.76 and an aqueous solubility of 2.65 g L(-1), HCA is more mobile in saturated media than BPA (Log K(ow) = 2.76; aqueous solubility = 0.31 g L(-1)), and therefore more likely to encounter oxic zones and undergo aerobic biodegradation. These findings corroborate that BPA is not inert under anoxic conditions and suggest that MnO2-mediated coupled abiotic-biotic processes may be relevant for controlling the fate and longevity of BPA in sediments and aquifers.
双酚 A（BPA）是一种具有较弱雌激素活性的环境污染物，在缺氧条件下难以被微生物降解，但易被二氧化锰（MnO2）进行非生物转化。在 pH 值为 7.2、存在 2 mM MnO2（0.017% w/w）的条件下，BPA 的降解遵循准一级动力学，其速率常数为 0.96（±0.03）min(-1)。4-羟基苯丁醇（HCA）是主要的转化产物，在摩尔基础上，初始 BPA 量的高达 64%以 HCA 的形式回收。MnO2 也能与 HCA 发生反应，尽管反应速率低 5 倍，但会发生 CO2 释放（即矿化）。在淡水沉积物建立的微宇宙中，HCA 在好氧条件下迅速生物降解，但在缺氧条件下则不会。HCA 的辛醇-水分配系数（Log K(ow)）为 0.76，水溶解度为 2.65 g L(-1)，比 BPA（Log K(ow) = 2.76；水溶解度 = 0.31 g L(-1)）更易在饱和介质中移动，因此更有可能遇到好氧区并经历好氧生物降解。这些发现证实了 BPA 在缺氧条件下并非惰性物质，并表明 MnO2 介导的耦合非生物-生物过程可能与控制 BPA 在沉积物和含水层中的命运和持久性有关。
