Kong I C, Bitton G, Koopman B, Jung K H
Department of Environmental Engineering Sciences, University of Florida, Gainesville 32611-6450, USA.
Rev Environ Contam Toxicol. 1995;142:119-47. doi: 10.1007/978-1-4612-4252-9_5.
The toxicity of heavy metals in the environment depends on a number of physicochemical and biological factors. The complexity of these relationships has encouraged the use of bioassays for direct measurement of the [table: see text] impact of toxic metals on selected test species. Fish and daphnid bioassays are well accepted by the scientific and regulatory communities, but their length (48 h or more) and the considerable time and effort needed to culture the test organisms make their application to sample screening problematical. Microbial and biochemical assays based on the inhibition of bioluminescence, enzyme activity, enzyme biosynthesis, growth, respiration, and heat production are typically faster and less expensive than the traditional and fish bioassays. Some of these tests approach or equal the sensitivity of daphnids to heavy metals. Since the soil acts as a sink for airborne and waste-applied metals, the uptake of metals by plants and the associated toxic impacts are important. Growth inhibition, enzyme induction, and production of stress proteins have been considered as toxicity end points. Enzymatic tests have been developed that are specific for heavy metal toxicity. Such tests can facilitate toxicity reduction evaluations. Detection of individual metals in the environment may eventually be possible using biosensors consisting of genetically engineered microorganisms. Direct solid-phase tests for soil, sediment, or sludge toxicity, using bacterial bioluminescence or enzyme activity as end points, have been developed. Such tests may complement traditional solid-phase toxicity tests using nematodes or earthworms as indicator organisms. Based on the work reviewed, we draw the following conclusions: 1. The Microtox assay is sensitive to mercury but would fail to detect the toxicity of certain metals, such as cadmium. Among all the microbial assays reviewed, the bioassay based on growth inhibition of the alga Selenastrum capricornutum appears to give the lowest EC50s, similar to those seen for daphnid bioassays. 2. Biosensors, using genetically engineered microorganisms, offer an elegant means of detecting the presence of specific heavy metals in environmental samples. However, at the present time, they are not designed for assessing heavy metal toxicity. 3. The use of bioassays specific for heavy metal toxicity can be useful for directly assessing the bioavailability of these toxicants in environmental samples, thus avoiding the need for fractionation.+4
环境中重金属的毒性取决于许多物理化学和生物学因素。这些关系的复杂性促使人们使用生物测定法来直接测量有毒金属对选定受试物种的影响。鱼类和水蚤生物测定法已为科学界和监管机构所广泛接受，但其持续时间（48小时或更长）以及培养受试生物所需的大量时间和精力使得它们在样本筛选中的应用存在问题。基于抑制生物发光、酶活性、酶生物合成、生长、呼吸和产热的微生物和生化测定法通常比传统的鱼类生物测定法更快且成本更低。其中一些测试方法的灵敏度接近或等同于水蚤对重金属的灵敏度。由于土壤是空气中和废弃物中金属的汇，植物对金属的吸收及其相关的毒性影响很重要。生长抑制、酶诱导和应激蛋白的产生已被视为毒性终点。已经开发出针对重金属毒性的酶促测试方法。此类测试有助于进行毒性降低评估。最终，使用由基因工程微生物组成的生物传感器可能能够检测环境中的单个金属。已经开发出以细菌生物发光或酶活性为终点的土壤、沉积物或污泥毒性的直接固相测试方法。此类测试可以补充使用线虫或蚯蚓作为指示生物的传统固相毒性测试。基于所综述的工作，我们得出以下结论：1. Microtox测定法对汞敏感，但无法检测某些金属（如镉）的毒性。在所综述的所有微生物测定法中，基于对羊角月芽藻生长抑制的生物测定法似乎给出了最低的半数有效浓度（EC50），与水蚤生物测定法的结果相似。2. 使用基因工程微生物的生物传感器为检测环境样品中特定重金属的存在提供了一种巧妙的方法。然而，目前它们并非设计用于评估重金属毒性。3. 使用针对重金属毒性的生物测定法可有助于直接评估环境样品中这些有毒物质的生物可利用性，从而无需进行分级分离。
