Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA.
Lyles School of Civil Engineering, Purdue University, West Lafayette, IN 47907, USA; Division of Environmental & Ecological Engineering, Purdue University, West Lafayette, IN 47907, USA.
Water Res. 2017 Sep 15;121:311-319. doi: 10.1016/j.watres.2017.05.052. Epub 2017 May 25.
Transport and release of waterborne organisms as a result of ballasting and de-ballasting operations is widely acknowledged to represent an important mechanism for invasions by non-indigenous species. Regulatory requirements have been implemented globally to require treatment of ballast water before its release to the environment as a means of minimizing risks of invasion. UV-based processes represent an option for ballast water treatment; however, their use will require development of appropriate methods for reactor validation. To address this need, Tetraselmis was examined as challenge organism using a most probable number (MPN) assay for quantification of the concentration of viable (reproductively active) cells in suspension. A low pressure collimated-beam reactor was used to investigate UV dose-response behavior of Tetraselmis. Based on the experimental conditions applied, Tetraselmis indicated 4.5-5 log units of inactivation for UV doses of approximately 120 mJ/cm, with no apparent change of resistance resulting from repeated exposure. A medium pressure UV collimated-beam reactor equipped with a series of narrow bandpass optical filters was used to investigate the action spectrum of Tetraselmis for wavelengths ranging from 228 nm-297 nm. Radiation with wavelengths in the range 254-280 nm was observed to be most efficient for inactivation of Tetraselmis. Additionally, DNA was extracted from Tetraselmis to allow measurement of its absorption spectrum. These results indicated strong absorbance from 254 nm to 280 nm, thereby suggesting that damage to DNA plays an important role in the inactivation of Tetraselmis sp. However, deviations of the action spectrum shape from the shape of the DNA absorption spectrum suggest that UV-induced damage to biomolecules other than DNA may contribute to Tetraselmis inactivation at some wavelengths in the UVC range.
压载和排空作业导致的水生生物的运输和释放，被广泛认为是外来物种入侵的一个重要机制。全球已实施监管要求，在将压载水排放到环境中之前，必须对其进行处理，以最大限度地降低入侵风险。基于紫外线的处理工艺是压载水处理的一种选择；然而，其使用将需要开发适当的方法来验证反应器。为了解决这一需求，使用最可能数（MPN）测定法，通过悬浮液中存活（生殖活跃）细胞的浓度来量化，将塔玛斯微绿球藻（Tetraselmis）作为挑战生物进行了检查。使用低压平行光束反应器研究了 Tetraselmis 的紫外线剂量-反应行为。根据应用的实验条件，Tetraselmis 在约 120 mJ/cm 的紫外线剂量下表现出 4.5-5 个对数单位的失活，并且由于重复暴露而没有表现出明显的抗性变化。使用配备一系列窄带通光学滤波器的中压紫外线平行光束反应器，研究了 Tetraselmis 在 228nm-297nm 波长范围内的作用光谱。观察到波长范围为 254-280nm 的辐射对 Tetraselmis 的灭活最为有效。此外，从 Tetraselmis 中提取 DNA，以允许测量其吸收光谱。这些结果表明，从 254nm 到 280nm 的吸收光谱具有很强的吸光度，从而表明 DNA 损伤在 Tetraselmis sp. 的失活中起着重要作用。然而，作用光谱形状与 DNA 吸收光谱形状的偏差表明，除 DNA 之外的生物分子的紫外线诱导损伤可能在 UVC 范围内的某些波长处对 Tetraselmis 的失活有贡献。
