Department of Environmental and Life Sciences, Toyohashi University of Technology, Aichi, Japan.
Microbes Environ. 2011;26(3):212-9. doi: 10.1264/jsme2.me11107. Epub 2011 May 11.
Laboratory-scale solid-phase denitrification (SPD) reactors for nitrate removal were constructed by acclimating activated sludge with poly (L-lactic acid) (PLLA) having weight-average molecular weights (M(w)) of 9,900, 12,000, and 45,100 g mol(-1). A good nitrate removal rate (3.5-5.3 mg NO(3)(-)-N g dry wt h(-1)) was found in the reactor containing PLLA of 9,900 g mol(-1), whereas the other two reactors with the higher M(w) PLLA showed low nitrate removal efficiency. Microbial community dynamics in the low M(w) PLLA-acclimated reactor were studied by 16S rRNA gene-targeted PCR-denaturing gradient gel electrophoresis and quinone profiling. Nonmetric multidimensional scaling analyses of these data sets revealed a marked population shift during acclimation of the SPD reactor with low M(w) PLLA. The 16S rRNA gene clone library and culture-dependent analyses showed that bacteria belonging to the family Comamonadaceae predominated and played the primary role in denitrification in the PLLA-using reactor; however, none of the bacterial isolates from the reactor degraded PLLA. These results suggest that the nitrate removal property of the PLLA-using SPD reactor is attained through the bioavailability of hydrolysates released abiotically from the solid substrate.
实验室规模的固相反硝化 (SPD) 反应器通过驯化含有重均分子量 (Mw) 分别为 9900、12000 和 45100 g/mol 的聚 (L-乳酸) (PLLA) 的活性污泥来构建，用于去除硝酸盐。在含有 9900 g/mol PLLA 的反应器中发现了良好的硝酸盐去除率（3.5-5.3 mg NO3--N/g [干重] h-1），而另外两个含有更高 Mw PLLA 的反应器则显示出低的硝酸盐去除效率。通过 16S rRNA 基因靶向 PCR-变性梯度凝胶电泳和醌分析研究了低 Mw PLLA 驯化的 SPD 反应器中的微生物群落动态。这些数据集的非度量多维标度分析显示，在低 Mw PLLA 的 SPD 反应器驯化过程中，种群发生了明显的变化。16S rRNA 基因克隆文库和培养依赖分析表明，属于 Comamonadaceae 科的细菌占优势，并在 PLLA 使用反应器中的反硝化中发挥主要作用；然而，从反应器中分离的任何细菌都不能降解 PLLA。这些结果表明，PLLA 利用 SPD 反应器的硝酸盐去除性能是通过从固体基质中无生命释放的水解产物的生物利用度来实现的。
