Calvin College, Department of Engineering, 1734 Knollcrest Circle SE, Grand Rapids, MI 49546 4493, USA.
Water Res. 2011 Mar;45(6):2270-80. doi: 10.1016/j.watres.2010.11.013. Epub 2010 Nov 19.
Using a continuous-flow rotating annular bioreactor, sorption of three selected antibiotics (sulfamethoxazole (SMX), ciprofloxacin (CIP), and erythromycin (ERY)) to bacterial biofilm was investigated. CIP had the greatest biofilm partition coefficient (K(oc) = 92,000 ± 10,000 L/kg) followed by ERY (K(oc) = 6000 ± 1000 L/kg) and then SMX (K(oc) = 4000 ± 1000 L/kg). Antibiotic sorption to biofilm did not correlate with experimentally-determined K(ow) values (CIP: -0.4; ERY: 0.98; SMX: <-0.59 at pH 7), suggesting that hydrophobic interactions do not drive the sorption of these relatively hydrophilic compounds to the biofilm. It appears that speciation (i.e. charge) and molecular size of the antibiotics are important in explaining their sorption to typically negatively charged biofilm. SMX is neutral to negatively charged at circumneutral pH while CIP and ERY are both positively charged. The decreased extent of sorption of ERY relative to CIP is likely due to the larger molecular size of ERY that results in a decreased rate of mass transfer (i.e. diffusion) to and through the biofilm. In conclusion, the results of this research suggest that hydrophobic interactions (predicted by K(ow)) do not control sorption of relatively hydrophilic antibiotics to biofilm and that antibiotic speciation and molecular size are important factors affecting the interactions between antibiotics and biofilm.
采用连续流动旋转环生物反应器，研究了三种选定抗生素（磺胺甲恶唑（SMX）、环丙沙星（CIP）和红霉素（ERY））对细菌生物膜的吸附作用。CIP 的生物膜分配系数（K（oc）=92000±10000 L/kg）最大，其次是 ERY（K（oc）=6000±1000 L/kg），然后是 SMX（K（oc）=4000±1000 L/kg）。抗生素对生物膜的吸附与实验测定的 K（ow）值无关（CIP：-0.4；ERY：0.98；SMX：在 pH 7 时<-0.59），表明疏水力不是这些相对亲水化合物吸附到生物膜的驱动力。似乎抗生素的形态（即电荷）和分子大小在解释它们对通常带负电荷的生物膜的吸附方面很重要。SMX 在中性至近中性 pH 时为中性至带负电荷，而 CIP 和 ERY 均带正电荷。ERY 的吸附程度相对于 CIP 降低，可能是由于 ERY 的分子尺寸较大，导致传质（即扩散）到生物膜并通过生物膜的速率降低。总之，这项研究的结果表明，疏水力（由 K（ow）预测）不能控制相对亲水抗生素对生物膜的吸附，抗生素的形态和分子大小是影响抗生素与生物膜相互作用的重要因素。
