Werlen Christoph, Jaspers Marco C M, van der Meer Jan Roelof
Process of Environmental Microbiology and Molecular Ecotoxicology, Swiss Federal Institute for Environmental Science and Technology (EAWAG), CH 8600 Dübendorf, Switzerland.
Appl Environ Microbiol. 2004 Jan;70(1):43-51. doi: 10.1128/AEM.70.1.43-51.2004.
Genetically constructed microbial biosensors for measuring organic pollutants are mostly applied in aqueous samples. Unfortunately, the detection limit of most biosensors is insufficient to detect pollutants at low but environmentally relevant concentrations. However, organic pollutants with low levels of water solubility often have significant gas-water partitioning coefficients, which in principle makes it possible to measure such compounds in the gas rather than the aqueous phase. Here we describe the first use of a microbial biosensor for measuring organic pollutants directly in the gas phase. For this purpose, we reconstructed a bioluminescent Pseudomonas putida naphthalene biosensor strain to carry the NAH7 plasmid and a chromosomally inserted gene fusion between the sal promoter and the luxAB genes. Specific calibration studies were performed with suspended and filter-immobilized biosensor cells, in aqueous solution and in the gas phase. Gas phase measurements with filter-immobilized biosensor cells in closed flasks, with a naphthalene-contaminated aqueous phase, showed that the biosensor cells can measure naphthalene effectively. The biosensor cells on the filter responded with increasing light output proportional to the naphthalene concentration added to the water phase, even though only a small proportion of the naphthalene was present in the gas phase. In fact, the biosensor cells could concentrate a larger proportion of naphthalene through the gas phase than in the aqueous suspension, probably due to faster transport of naphthalene to the cells in the gas phase. This led to a 10-fold lower detectable aqueous naphthalene concentration (50 nM instead of 0.5 micro M). Thus, the use of bacterial biosensors for measuring organic pollutants in the gas phase is a valid method for increasing the sensitivity of these valuable biological devices.
用于测量有机污染物的基因构建微生物生物传感器大多应用于水性样品。不幸的是，大多数生物传感器的检测限不足以检测低浓度但与环境相关的污染物。然而，水溶性低的有机污染物通常具有显著的气 - 水分配系数，这原则上使得在气相而非水相中测量此类化合物成为可能。在此，我们描述了首次使用微生物生物传感器直接在气相中测量有机污染物。为此，我们重建了一种发光恶臭假单胞菌萘生物传感器菌株，使其携带NAH7质粒以及sal启动子与luxAB基因之间的染色体插入基因融合体。使用悬浮和滤膜固定的生物传感器细胞，分别在水溶液和气相中进行了特定的校准研究。在封闭烧瓶中，对含有萘污染水相的滤膜固定生物传感器细胞进行气相测量，结果表明生物传感器细胞能够有效测量萘。滤膜上的生物传感器细胞的光输出增加，与添加到水相中的萘浓度成正比，尽管气相中仅存在少量萘。实际上，生物传感器细胞通过气相比在水悬浮液中能够浓缩更大比例的萘，这可能是由于萘在气相中向细胞的传输速度更快。这使得可检测的水相萘浓度降低了10倍（50 nM而非0.5 μM）。因此，使用细菌生物传感器在气相中测量有机污染物是提高这些有价值的生物装置灵敏度的有效方法。
